JP6171740B2

JP6171740B2 - Optical device and image display apparatus

Info

Publication number: JP6171740B2
Application number: JP2013181104A
Authority: JP
Inventors: 横山　修; 修横山; 米窪　政敏; 政敏米窪; 文香山田
Original assignee: Seiko Epson Corp
Current assignee: Seiko Epson Corp
Priority date: 2013-09-02
Filing date: 2013-09-02
Publication date: 2017-08-02
Anticipated expiration: 2033-09-02
Also published as: JP2015049376A

Description

本発明は、導光板と回折光学素子とを用いた光学デバイス、並びにその光学デバイスを備えた画像表示装置に関する。 The present invention relates to an optical device using a light guide plate and a diffractive optical element, and an image display apparatus including the optical device.

近年、画像投影装置の１つとして画像表示装置からの画像を、導光板を用いて、観察者の眼前まで導光して表示させるヘッドマウントディスプレイが商品化され、さらなる小型化、広画角化、高効率化に関する開発が行われている。その中で、導光板内への入射、出射を行うための素子の１つとして回折光学素子を用いた装置が提案されている（例えば、特許文献１及び特許文献２）。 In recent years, head mounted displays that display images from an image display device as one of the image projection devices in front of the viewer's eyes using a light guide plate have been commercialized, resulting in further miniaturization and wider angle of view. Development related to high efficiency is being carried out. Among them, an apparatus using a diffractive optical element is proposed as one of elements for entering and exiting the light guide plate (for example, Patent Document 1 and Patent Document 2).

このような回折光学素子を用いた装置では、導光板を伝播してきた光は、出射用の回折光学素子領域で複数回この回折光学素子に入射し、その度に導光板から取り出され、観察者の眼に届く。したがって、観察者の眼の位置が水平方向に多少移動しても虚像が観察できる。 In such an apparatus using a diffractive optical element, light propagating through the light guide plate enters the diffractive optical element a plurality of times in the diffractive optical element region for output, and is taken out of the light guide plate each time. Reach the eyes. Therefore, a virtual image can be observed even if the position of the observer's eyes slightly moves in the horizontal direction.

しかしながら、回折光学素子の回折特性には大きな波長依存性があるため、観察される虚像の色むらが大きくなることがある。そこで、従来から、回折光学素子を用いた装置では、色むらを改善するための対策が施されている。 However, since the diffraction characteristics of the diffractive optical element have a large wavelength dependency, the color unevenness of the observed virtual image may increase. Therefore, conventionally, in an apparatus using a diffractive optical element, measures for improving color unevenness have been taken.

特許文献１に開示された画像表示装置では、回折効率の波長依存性による色ごとの効率差を低減させるために、複数の導光板を用意し、それぞれの導光板を伝播させる色（波長成分）を限定している。 In the image display device disclosed in Patent Document 1, in order to reduce the efficiency difference for each color due to the wavelength dependence of diffraction efficiency, a plurality of light guide plates are prepared, and the colors (wavelength components) propagate through the respective light guide plates. Is limited.

また、特許文献２に開示された画像表示装置では、出射用の回折光学素子の回折効率を位置によって変化させ、出射される光量の位置による差を少なくし、出射させる光量の分布を均一化する技術が開示されている。 In the image display device disclosed in Patent Document 2, the diffraction efficiency of the diffractive optical element for emission is changed depending on the position, the difference due to the position of the emitted light amount is reduced, and the distribution of the emitted light amount is made uniform. Technology is disclosed.

一方、観察する虚像のサイズを大きくしたい場合、導光板へ入射させる光の角度範囲を大きく（例えば全角で２０度以上に）する必要がある。大きな角度範囲に亘って回折効率を高くできる回折光学素子として、体積ホログラムよりも表面レリーフ型回折格子の方がこのましく、このような表面レリーフ型回折格子を用いた装置も提案されている（例えば、特許文献３）。 On the other hand, when it is desired to increase the size of the virtual image to be observed, it is necessary to increase the angle range of light incident on the light guide plate (for example, 20 degrees or more in all angles). As a diffractive optical element capable of increasing the diffraction efficiency over a large angle range, a surface relief type diffraction grating is more preferable than a volume hologram, and an apparatus using such a surface relief type diffraction grating has also been proposed ( For example, Patent Document 3).

特表２００８−５２３４３４号公報Special table 2008-523434 gazette 特表２００８−５３５０３２号公報Special table 2008-535032 gazette 特表２００９−５３９１２９号公報Special table 2009-539129

しかしながら、特許文献１の装置では、出射用の回折光学素子の回折効率は、位置によらずに一定のため、入射用の回折光学素子から遠い位置ほど出射させる光量が減少し、出射用の回折光学素子における出射光量の分布が均一ではないという問題があった。 However, in the apparatus of Patent Document 1, the diffraction efficiency of the diffractive optical element for output is constant regardless of the position. There is a problem that the distribution of the emitted light quantity in the optical element is not uniform.

また、特許文献２の装置では、出射用の回折光学素子の回折効率を位置によって変化させ、出射される光量の位置による差を少なくすることが行われている。しかしながら、波長が長い光は導光板を伝播する角度が大きく、出射用の回折光学素子領域で回折格子に入射する回数は少ない。この場合は回折効率を位置によって変化させることで外へ取り出される光量の総量が少なくなる、という問題があった。 Further, in the apparatus of Patent Document 2, the diffraction efficiency of the diffractive optical element for emission is changed depending on the position to reduce the difference due to the position of the emitted light amount. However, light having a long wavelength propagates through the light guide plate at a large angle, and the number of times it enters the diffraction grating in the diffractive optical element region for emission is small. In this case, there is a problem that the total amount of light extracted outside is reduced by changing the diffraction efficiency depending on the position.

さらに、特許文献３の装置では、回折光学素子として表面レリーフ型回折格子を用いているため、導光板へ入射させる光の角度範囲を大きくすることができるが、出射用の表面レリーフ型回折格子の回折効率を位置によって変化させることを行っていないため、出射光量の分布が均一ではないという問題があった。 Furthermore, in the apparatus of Patent Document 3, since the surface relief type diffraction grating is used as the diffractive optical element, the angle range of the light incident on the light guide plate can be increased. Since the diffraction efficiency is not changed depending on the position, there is a problem that the distribution of the emitted light quantity is not uniform.

そこで、本発明は、上述した事情を考慮して、広い角度範囲に亘って回折効率を高くできる表面レリーフ型回折光学素子を用いた導光板構造において、色むらを低減できると共に出射光量分布を均一化でき光学デバイスの構造を提供することを解決課題とする。 Accordingly, in consideration of the above-described circumstances, the present invention can reduce color unevenness and make the emitted light amount distribution uniform in a light guide plate structure using a surface relief type diffractive optical element that can increase diffraction efficiency over a wide angle range. It is an object of the present invention to provide an optical device structure that can be realized.

上記課題を解決するために、本発明に係る光学デバイスの第1の態様は、第１光入射部と第１光出射部とを備えた第１導光体と、第２光入射部と第２光出射部とを備えた第２導光体と、前記第２導光体の前記第２光出射部に設けられ、前記第２導光体の内部を導光した光の少なくとも一部を回折させて前記第２導光体の外部に取り出す第１回折光学素子と、
前記第１導光体の前記第１光出射部に設けられ、前記第１導光体の内部を導光した光の少なくとも一部及び前記第１回折光学素子で取り出された光の少なくとも一部を取り出す第２回折光学素子と、を有し、前記第１導光体及び前記第２導光体に入射する入射光は、一部が前記第１光入射部から前記第１導光体の内部に入射して導光され、他の一部が前記第２光入射部から前記第２導光体の内部に入射して導光され、前記第２導光体の内部を導光する光は、前記第１導光体の内部を導光する光よりも長波長の光を多く含み、前記第２回折光学素子は、前記第１光入射部に近い側と、前記第１光入射部から遠い側とで、回折効率が異なる部分を含み、前記第１回折光学素子は、回折効率がほぼ一定であることを特徴とする。 In order to solve the above problems, a first aspect of the optical device according to the present invention includes a first light guide including a first light incident portion and a first light emitting portion, a second light incident portion, A second light guide including two light emitting portions; and at least a part of the light guided in the second light guide and provided in the second light emitting portion of the second light guide. A first diffractive optical element that is diffracted and taken out of the second light guide;
At least a part of the light that is provided in the first light emitting part of the first light guide and guided through the inside of the first light guide and at least a part of the light extracted by the first diffractive optical element A second diffractive optical element for taking out light, and a part of incident light incident on the first light guide and the second light guide is from the first light incident portion of the first light guide. Light that enters and is guided to the inside, and part of the light that enters the second light guide from the second light incident portion and is guided to guide the inside of the second light guide. Includes more light having a longer wavelength than the light guided inside the first light guide, and the second diffractive optical element includes a side closer to the first light incident part, and the first light incident part. The first diffractive optical element includes a portion where the diffraction efficiency is different on the side far from the distance, and the diffraction efficiency is substantially constant.

上述した本発明に係る光学デバイスの第１の態様によれば、第１導光体に入射する入射光は、一部が第１光入射部から第１導光体の内部に入射して導光され、他の一部が第２光入射部から第２導光体の内部に入射して導光される。第１導光体の内部に入射して導光される光の少なくとも一部は、第１導光体の第１光出射部に設けられた第２回折光学素子により第１導光体から取り出される。第２導光体の内部に入射して導光される光の少なくとも一部は、第２導光体の第２光出射部に設けられた第１回折光学素子により、第２導光体の外部に取り出される。さらに、第１回折光学素子で取り出された光の少なくとも一部は、第２回折光学素子により取り出される。このとき、第２回折光学素子は、第１光入射部に近い側と、第１光入射部から遠い側とで、回折効率が異なる部分を含むので、出射光量分布が均一化される。また、第１回折光学素子は、回折効率がほぼ一定なので、第１導光体内に導光される光よりも長波長の光を多く含む光が第２導光体内に導光され、第２導光体内を大きな角度で伝播し、第１回折光学素子に入射する回数が少ない場合でも、出射光量を増加させる。以上のように、この態様によれば、第１導光体と第２導光体の２つの導光体を用いることにより、回折効率の波長依存性による色ごとの効率差を低減し、第２回折光学素子に回折効率が異なる部分を設けたことにより出射光量分布の均一化を図り、かつ、第１回折光学素子は、回折効率がほぼ一定としたので、長波長側の光についても十分な出射光量を得ることができ、全体として、出射光量分布を均一化して色むらを抑制した光学デバイスが提供される。 According to the first aspect of the optical device according to the present invention described above, a part of the incident light incident on the first light guide is incident on the inside of the first light guide from the first light incident part. The other part is incident on the inside of the second light guide from the second light incident part and guided. At least a portion of the light that enters and is guided into the first light guide is extracted from the first light guide by the second diffractive optical element provided in the first light emitting portion of the first light guide. It is. At least a part of the light that enters the second light guide and is guided by the second light guide is provided by the first diffractive optical element provided in the second light emitting portion of the second light guide. Take out to the outside. Furthermore, at least a part of the light extracted by the first diffractive optical element is extracted by the second diffractive optical element. At this time, since the second diffractive optical element includes a portion where the diffraction efficiency is different between the side closer to the first light incident portion and the side far from the first light incident portion, the emitted light quantity distribution is made uniform. In addition, since the diffraction efficiency of the first diffractive optical element is substantially constant, light containing light having a longer wavelength than the light guided into the first light guide is guided into the second light guide. Even when the number of times of propagation through the light guide at a large angle and incidence on the first diffractive optical element is small, the amount of emitted light is increased. As described above, according to this aspect, by using the two light guides of the first light guide and the second light guide, the efficiency difference for each color due to the wavelength dependency of the diffraction efficiency is reduced, The two diffractive optical elements are provided with portions having different diffraction efficiencies so that the distribution of the quantity of emitted light is made uniform, and the diffraction efficiency of the first diffractive optical element is substantially constant. Thus, an optical device that can obtain a large amount of emitted light, and uniforms the emitted light amount distribution and suppresses color unevenness as a whole is provided.

上述した本発明に係る光学デバイスの第１の態様において、前記第１回折光学素子は、一方の面に第１凹凸構造を備えた表面レリーフ型の回折格子であり、前記第２導光体の前記第２光入射部と前記第２光出射部との両方を含む断面視において、前記第1凹凸構造の凸部を構成する面のうち前記第２光出射部と交差する面が、前記第２光出射部に垂直な方向に対して傾斜していることが好ましい。この場合には、第１回折光学素子に表面レリーフ型回折格子を用いたことにより広い角度範囲に亘って回折効率を高くすると共に、長波長側の光についても十分な出射光量を得ることができ、全体として、出射光量分布を均一化して色むらを抑制した光学デバイスが提供される。 In the first aspect of the optical device according to the present invention described above, the first diffractive optical element is a surface relief type diffraction grating having a first concavo-convex structure on one surface, and the second light guide In a cross-sectional view including both the second light incident portion and the second light emitting portion, a surface that intersects the second light emitting portion among the surfaces constituting the convex portion of the first uneven structure is the first light emitting portion. It is preferable to incline with respect to the direction perpendicular to the two light emitting portions. In this case, the surface relief type diffraction grating is used for the first diffractive optical element, so that the diffraction efficiency can be increased over a wide angle range, and a sufficient amount of emitted light can be obtained even for light on the long wavelength side. As a whole, an optical device is provided in which the emitted light quantity distribution is made uniform and color unevenness is suppressed.

上述した本発明に係る光学デバイスの第１の態様において、前記第２回折光学素子は、一方の面に第２凹凸構造を備えた表面レリーフ型の回折格子であり、前記第１導光体の前記第１光入射部と前記第１光出射部との両方を含む断面視において、前記第２凹凸構造の凸部を構成する面のうち前記第１光出射部と交差する面が、前記第１光出射部に垂直な方向に対して傾斜していることが好ましい。この場合には、第２回折光学素子に表面レリーフ型回折格子を用いたことにより広い角度範囲に亘って回折効率を高くすると共に、長波長側の光についても十分な出射光量を得ることができ、全体として、出射光量分布を均一化して色むらを抑制した光学デバイスが提供される。 In the first aspect of the optical device according to the present invention described above, the second diffractive optical element is a surface relief type diffraction grating having a second concavo-convex structure on one surface, and the first light guide In a cross-sectional view including both the first light incident portion and the first light emitting portion, a surface that intersects the first light emitting portion among the surfaces constituting the convex portion of the second uneven structure is the first light emitting portion. It is preferable to incline with respect to the direction perpendicular to the one light emitting part. In this case, the surface relief type diffraction grating is used for the second diffractive optical element, so that the diffraction efficiency can be increased over a wide angle range, and a sufficient amount of emitted light can be obtained even for light on the long wavelength side. As a whole, an optical device is provided in which the emitted light quantity distribution is made uniform and color unevenness is suppressed.

上述した本発明に係る光学デバイスの第１の態様において、前記第２回折光学素子は、一方の面に第２凹凸構造を備えた表面レリーフ型の回折格子であり、前記第１導光体の前記第１光入射部と前記第１光出射部との両方を含む断面視において、前記第２凹凸構造の凹部の深さが、前記第１光入射部に近い側から、前記第１光入射部から遠い側にかけて、徐々に、あるいは、段階的に変化していることが好ましい。この場合には、第１光入射部に近い側に到達する光の方が、第１光入射部から遠い側に到達する光よりも多くなるが、第１光入射部に近い側から、第１光入射部から遠い側にかけて、徐々に、あるいは、段階的に変化しているので、回折効率が変化し、結果として出射光量分布の均一化が図られる。 In the first aspect of the optical device according to the present invention described above, the second diffractive optical element is a surface relief type diffraction grating having a second concavo-convex structure on one surface, and the first light guide In a cross-sectional view including both the first light incident portion and the first light emitting portion, the depth of the concave portion of the second concavo-convex structure is from the side closer to the first light incident portion. It is preferable to change gradually or stepwise from the part to the far side. In this case, the amount of light reaching the side closer to the first light incident part is larger than the light reaching the side farther from the first light incident part, but from the side closer to the first light incident part, Since it changes gradually or in steps from one light incident part to the far side, the diffraction efficiency changes, and as a result, the emitted light quantity distribution is made uniform.

上述した本発明に係る光学デバイスの第１の態様において、前記第２回折光学素子は、一方の面に第２凹凸構造を備えた表面レリーフ型の回折格子であり、前記第１導光体の前記第１光入射部と前記第１光出射部との両方を含む断面視において、前記第２凹凸構造の充填率が、前記第１光入射部に近い側から、前記第１光入射部から遠い側にかけて、徐々に、あるいは、段階的に変化していることが好ましい。この場合には、第１光入射部に近い側に到達する光の方が、第１光入射部から遠い側に到達する光よりも多くなるが、第１光入射部に近い側から、第１光入射部から遠い側にかけて、徐々に、あるいは、段階的に変化しているので、回折効率が変化し、結果として出射光量分布の均一化が図られる。 In the first aspect of the optical device according to the present invention described above, the second diffractive optical element is a surface relief type diffraction grating having a second concavo-convex structure on one surface, and the first light guide In a cross-sectional view including both the first light incident part and the first light emitting part, the filling ratio of the second uneven structure is from the side close to the first light incident part, from the first light incident part. It is preferable to change gradually or in steps from the far side. In this case, the amount of light reaching the side closer to the first light incident part is larger than the light reaching the side farther from the first light incident part, but from the side closer to the first light incident part, Since it changes gradually or in steps from one light incident part to the far side, the diffraction efficiency changes, and as a result, the emitted light quantity distribution is made uniform.

上述した本発明に係る光学デバイスの第１の態様において、前記第２回折光学素子は、前記第１導光体の前記第１光入射部と前記第１光出射部との両方を含む断面視において、前記第２凹凸構造の凸部を構成する面のうち前記第１光出射部と交差する面が、前記第１光出射部に垂直な方向に対して傾斜していることが好ましい。この場合には、回折効率を高めて十分な出射光量を得ることができる。 In the first aspect of the optical device according to the present invention described above, the second diffractive optical element is a cross-sectional view including both the first light incident portion and the first light emitting portion of the first light guide. In the above, it is preferable that a surface intersecting the first light emitting portion among the surfaces constituting the convex portion of the second concavo-convex structure is inclined with respect to a direction perpendicular to the first light emitting portion. In this case, it is possible to increase the diffraction efficiency and obtain a sufficient amount of emitted light.

上述した本発明に係る光学デバイスの第１の態様において、前記第１導光体の前記第１光入射部に設けられ、前記入射光の一部を回折させて前記第１導光体の内部に入射させる第３回折光学素子と、前記第２導光体の前記第２光入射部に設けられ、前記入射光の他の一部を回折させて前記第２導光体の内部に入射させる第４回折光学素子とを有することが好ましい。この場合には、入射光を効率良く第１導光体および第２導光体の内部に入射させて導光させることができる。 1st aspect of the optical device which concerns on this invention mentioned above WHEREIN: It is provided in the said 1st light-incidence part of a said 1st light guide, and diffracts a part of said incident light, and the inside of a said 1st light-guide A third diffractive optical element that is incident on the second light guide and the second light incident portion of the second light guide, and diffracts the other part of the incident light to enter the second light guide. It is preferable to have a fourth diffractive optical element. In this case, incident light can be efficiently introduced into the first light guide and the second light guide to guide the light.

上述した本発明に係る光学デバイスの第１の態様において、前記第３回折光学素子の格子周期は、前記第４回折光学素子の格子周期と異なる格子周期であり、かつ、前記第２回折光学素子の格子周期と同じ格子周期であり、前記第４回折光学素子の格子周期は、前記第１回折光学素子の格子周期と同じ格子周期であることが好ましい。この場合には、第２回折光学素子により回折させて第１導光体に入射させた光と同じ波長の光を第３回折光学素子により第１導光体から取り出すことができ、第３回折光学素子により回折させて第１導光体に入射させた光と同じ波長の光を第２回折光学素子により第１導光体から取り出すことができ、第４回折光学素子により回折させて第２導光体に入射させた光と同じ波長の光を第１回折光学素子により第２導光体から取り出すことができる。 In the first aspect of the optical device according to the present invention described above, the grating period of the third diffractive optical element is a grating period different from the grating period of the fourth diffractive optical element, and the second diffractive optical element Preferably, the grating period of the fourth diffractive optical element is the same as the grating period of the first diffractive optical element. In this case, light having the same wavelength as the light diffracted by the second diffractive optical element and incident on the first light guide can be extracted from the first light guide by the third diffractive optical element. Light having the same wavelength as the light incident on the first light guide after being diffracted by the optical element can be extracted from the first light guide by the second diffractive optical element, and diffracted by the fourth diffractive optical element to obtain the second light. Light having the same wavelength as the light incident on the light guide can be extracted from the second light guide by the first diffractive optical element.

上述した本発明に係る光学デバイスの第１の態様において、前記第３回折光学素子の格子周期は、前記第４回折光学素子の格子周期よりも短い格子周期であることが好ましい。この場合には、第１導光体に入射させる光の波長よりも長い波長の光を第２導光体に入射させることができる。 In the first aspect of the optical device according to the present invention described above, it is preferable that the grating period of the third diffractive optical element is shorter than the grating period of the fourth diffractive optical element. In this case, light having a wavelength longer than the wavelength of light incident on the first light guide can be incident on the second light guide.

上述した本発明に係る光学デバイスの第１の態様において、前記第３回折光学素子は、一方の面に第３凹凸構造を備えた表面レリーフ型の回折格子であり、前記第１導光体の前記第１光入射部と前記第１光出射部との両方を含む断面視において、前記第３凹凸構造の凸部を構成する面のうち前記第１光入射部と交差する面が、前記第１光入射部に垂直な方向に対して傾斜し、前記第４回折光学素子は、一方の面に第４凹凸構造を備えた表面レリーフ型の回折格子であり、前記第２導光体の前記第２光入射部と前記第２光出射部との両方を含む断面視において、前記第４凹凸構造の凸部を構成する面のうち前記第２光入射部と交差する面が、前記第２光入射部に垂直な方向に対して傾斜していることが好ましい。この場合には、第３回折光学素子と第４回折光学素子に、傾斜面を有する凹凸構造を備えた表面レリーフ型回折格子を用いたことにより広い角度範囲に亘って回折効率を高くすると共に、長波長側の光についても十分な出射光量を得ることができ、全体として、出射光量分布を均一化して色むらを抑制した光学デバイスが提供される。 In the first aspect of the optical device according to the present invention described above, the third diffractive optical element is a surface relief type diffraction grating having a third concavo-convex structure on one surface, and the first light guide In a cross-sectional view including both the first light incident portion and the first light emitting portion, a surface that intersects the first light incident portion among the surfaces constituting the convex portion of the third uneven structure is the first The fourth diffractive optical element is a surface relief type diffraction grating having a fourth concavo-convex structure on one surface, which is inclined with respect to a direction perpendicular to one light incident part, and the second light guide In a cross-sectional view including both the second light incident portion and the second light emitting portion, a surface that intersects the second light incident portion among the surfaces constituting the convex portion of the fourth uneven structure is the second It is preferable to incline with respect to the direction perpendicular to the light incident part. In this case, the third diffractive optical element and the fourth diffractive optical element use a surface relief type diffraction grating having a concavo-convex structure having an inclined surface to increase the diffraction efficiency over a wide angle range, A sufficient amount of emitted light can be obtained even for light on the long wavelength side, and as a whole, an optical device is provided in which the emitted light amount distribution is made uniform and color unevenness is suppressed.

上述した本発明に係る光学デバイスの第１の態様において、前記第４回折光学素子は、前記第２光入射部に垂直な方向から見た平面視において、前記第３回折光学素子よりも前記第２光出射部側に位置し、前記第１回折光学素子は、前記第２光出射部に垂直な方向から見た平面視において、前記第２回折光学素子よりも前記第２光入射部側に位置していることが好ましい。この場合には、入射光及び出射光の光軸に沿って各回折光学素子が配置されているので、入射時及び出射時における損失を低下させる。 In the first aspect of the optical device according to the present invention described above, the fourth diffractive optical element has the first diffractive optical element more than the third diffractive optical element in a plan view as viewed from a direction perpendicular to the second light incident portion. The first diffractive optical element is located on the side of the second light emitting part, and the first diffractive optical element is closer to the second light incident part than the second diffractive optical element in a plan view as viewed from a direction perpendicular to the second light emitting part. Preferably it is located. In this case, since each diffractive optical element is arranged along the optical axis of incident light and outgoing light, the loss at the time of incident and outgoing is reduced.

次に、本発明に係る画像表示装置は、上述した本発明に係る光学デバイスと画像光を発する画像形成部とを備える。そのような画像表示装置は、液晶ディスプレイ等の画像形成部やコリメート光学系を備えてもよく、ヘッドマウントディスプレイ等のように観察者の頭部に装着する形態に適合させることができる。 Next, an image display apparatus according to the present invention includes the above-described optical device according to the present invention and an image forming unit that emits image light. Such an image display device may include an image forming unit such as a liquid crystal display and a collimating optical system, and can be adapted to a form mounted on the observer's head such as a head-mounted display.

このように、本発明によれば、ヘッドマウントディスプレイ等のように観察者の頭部に装着する形態の画像表示装置においても、製造上の困難性を解消して製造コストの低廉化を図りつつ、観察者の顔に対するフィッティング性を向上させるとともに、広い画角を得ることができる光学デバイスを得ることができる。 As described above, according to the present invention, even in an image display device that is mounted on the observer's head, such as a head-mounted display, the manufacturing difficulty is reduced and the manufacturing cost is reduced. In addition, it is possible to obtain an optical device that can improve the fitting property to the face of the observer and can obtain a wide angle of view.

なお、上記本発明に係る画像表示装置において「画像形成部」とは、例えば画像を表示する液晶ディスプレイやレーザー光を走査することにより観察者に画像として認識させるレーザー走査式ディスプレイなどの装置、及び画像表示から出射された画像光を集光及び変換する光学系を含む。 In the image display device according to the present invention, the “image forming unit” refers to, for example, a liquid crystal display that displays an image, a laser scanning display that causes an observer to recognize an image by scanning laser light, and the like. It includes an optical system that collects and converts image light emitted from the image display.

第１実施形態に係るヘッドマウントディスプレイの全体像の一例を示す斜視図である。It is a perspective view which shows an example of the whole image of the head mounted display which concerns on 1st Embodiment. 第１実施形態に係るヘッドマウントディスプレイの左眼用光学系の内部構造及び導波路の一例を示す要部断面図である。It is principal part sectional drawing which shows an example of the internal structure of the optical system for left eyes of the head mounted display which concerns on 1st Embodiment, and a waveguide. 傾斜のない回折格子における回折の態様を説明する要部断面図である。It is principal part sectional drawing explaining the aspect of the diffraction in the diffraction grating without an inclination. 傾斜のある回折格子における回折の態様を説明する要部断面図である。It is principal part sectional drawing explaining the aspect of diffraction in the diffraction grating with an inclination. 第２回折光学素子が配置された部分の拡大図である。It is an enlarged view of the part by which the 2nd diffractive optical element is arrange | positioned. 第２回折光学素子と比較される比較例の回折光学素子が配置された部分の拡大図である。It is an enlarged view of the part by which the diffractive optical element of the comparative example compared with a 2nd diffractive optical element is arrange | positioned. 第２回折光学素子と比較例の出射光量分布の一例を示す図である。It is a figure which shows an example of the emitted light quantity distribution of a 2nd diffractive optical element and a comparative example. 第４回折光学素子が配置された部分の拡大図である。It is an enlarged view of the part by which the 4th diffractive optical element is arrange | positioned. 第１回折光学素子、第２回折光学素子、第３回折光学素子、及び第４回折光学素子の配置位置の一例を説明する説明図である。It is explanatory drawing explaining an example of the arrangement position of a 1st diffractive optical element, a 2nd diffractive optical element, a 3rd diffractive optical element, and a 4th diffractive optical element. 第１回折光学素子、第２回折光学素子、第３回折光学素子、及び第４回折光学素子の配置位置の一例を説明する説明図である。It is explanatory drawing explaining an example of the arrangement position of a 1st diffractive optical element, a 2nd diffractive optical element, a 3rd diffractive optical element, and a 4th diffractive optical element. 第２実施形態における第２回折光学素子が配置された部分の拡大図である。It is an enlarged view of the part by which the 2nd diffractive optical element in 2nd Embodiment is arrange | positioned. 第２実施形態における第２回折光学素子の充填率を説明する説明図である。It is explanatory drawing explaining the filling factor of the 2nd diffractive optical element in 2nd Embodiment. 第３実施形態における第２回折光学素子が配置された部分の拡大図である。It is an enlarged view of the part by which the 2nd diffractive optical element in 3rd Embodiment is arrange | positioned. 第４実施形態における第２回折光学素子が配置された部分の拡大図である。It is an enlarged view of the part by which the 2nd diffractive optical element in 4th Embodiment is arrange | positioned.

以下、添付の図面を参照しながら本発明に係る様々な実施の形態を説明する。なお、図面においては、各部の寸法の比率は実際のものとは適宜に異ならせてある。また、以下に説明する実施形態では、本発明の光学デバイスを、観察者の頭部に装着する形態の画像表示装置の一例であるヘッドマウントディスプレイに適用した場合を例に説明するが、かかる実施の形態は、本発明の一態様を示すものであり、この発明を限定するものではなく、本発明の技術的思想の範囲内に任意に変更可能である。 Hereinafter, various embodiments according to the present invention will be described with reference to the accompanying drawings. In the drawings, the ratio of dimensions of each part is appropriately changed from the actual one. In the embodiment described below, the optical device of the present invention is described as an example applied to a head-mounted display that is an example of an image display device that is mounted on the head of an observer. The embodiment shows one embodiment of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the technical idea of the present invention.

＜Ａ：第１実施形態＞
（ヘッドマウントディスプレイの全体構成）
図１は、第１実施形態に係るヘッドマウントディスプレイ１００の全体像の一例を示す斜視図である。図１に示すように、本実施形態に係るヘッドマウントディスプレイ１００は、眼鏡のような外観を有するヘッドマウントディスプレイであり、このヘッドマウントディスプレイ１００を装着した観察者に対して虚像による画像光を認識させることができるとともに、観察者に外界像をシースルーで観察させることができる。 <A: First Embodiment>
(Overall configuration of head mounted display)
FIG. 1 is a perspective view showing an example of the entire image of the head mounted display 100 according to the first embodiment. As shown in FIG. 1, the head mounted display 100 according to the present embodiment is a head mounted display having an appearance like glasses, and recognizes image light based on a virtual image for an observer wearing the head mounted display 100. It is possible to cause the observer to observe the outside world image with see-through.

具体的にヘッドマウントディスプレイ１００は、導光板２０と、導光板２０を支持する左右一対のテンプル１３１，１３２と、テンプル１３１，１３２に付加された一対の画像形成装置１１１，１１２とを備える。ここで、図面上において、導光板２０の左側と画像形成装置１１１とを組み合わせた第１表示装置１００Ａは、右眼用の虚像を形成する部分であり、単独でも画像表示装置として機能する。また、図面上において、導光板２０で右側と画像形成装置１１２とを組み合わせた第２表示装置１００Ｂは、左眼用の虚像を形成する部分であり、単独でも画像表示装置として機能する。 Specifically, the head mounted display 100 includes a light guide plate 20, a pair of left and right temples 131 and 132 that support the light guide plate 20, and a pair of image forming apparatuses 111 and 112 attached to the temples 131 and 132. Here, in the drawing, the first display device 100A in which the left side of the light guide plate 20 and the image forming device 111 are combined is a portion that forms a virtual image for the right eye, and functions alone as an image display device. In the drawing, the second display device 100B in which the right side and the image forming device 112 are combined with the light guide plate 20 is a portion that forms a virtual image for the left eye, and functions alone as an image display device.

このようなヘッドマウントディスプレイ１００の内部構造及び導光板について説明する。図２は、本実施形態に係るヘッドマウントディスプレイの内部構造及び導光板の一例を模式的に示す要部断面図である。図２は、本実施形態に係る左眼用光学系の内部構造及び導光板を示す要部断面図である。なお、図示を省略するが、右眼用光学系の内部構造及び導光板については図２を反転させて左右を入れ替えた構成となっている。図２に示すように、第１表示装置１００Ａ及び第２表示装置１００Ｂは、画像形成部１０と、導光板２０とを備える。 The internal structure and light guide plate of the head mounted display 100 will be described. FIG. 2 is a main part sectional view schematically showing an example of the internal structure and the light guide plate of the head mounted display according to the present embodiment. FIG. 2 is a cross-sectional view of the main part showing the internal structure of the left-eye optical system and the light guide plate according to the present embodiment. In addition, although illustration is abbreviate | omitted, about the internal structure and light guide plate of the optical system for right eyes, it has the structure which reversed FIG. 2 and replaced right and left. As shown in FIG. 2, the first display device 100 </ b> A and the second display device 100 </ b> B include an image forming unit 10 and a light guide plate 20.

画像形成部１０は、画像表示装置１１と、投射光学系１２とを有する。このうち、画像表示装置１１は、本実施形態では、液晶表示デバイスであり、光源によって照明され赤（Ｒ）、緑（Ｇ）、青（Ｂ）の３色を含む画像光１３を発生させ、投射光学系１２に向けて出射する。画像表示装置１１としては、有機ＥＬパネルを用いることもできる。一方、投射光学系１２は、画像表示装置１１上の各点から出射された画像光を平行状態の光束に変換して、導光板２０に入射させるコリメートレンズである。特に、本実施形態において、画像形成部１０は、広い画角を得るために、パネルに対して垂直な法線方向に対して傾斜されて配置されている。 The image forming unit 10 includes an image display device 11 and a projection optical system 12. Among these, the image display apparatus 11 is a liquid crystal display device in this embodiment, and is illuminated by a light source to generate image light 13 including three colors of red (R), green (G), and blue (B), The light is emitted toward the projection optical system 12. An organic EL panel can also be used as the image display device 11. On the other hand, the projection optical system 12 is a collimating lens that converts the image light emitted from each point on the image display device 11 into a light beam in a parallel state and enters the light guide plate 20. In particular, in the present embodiment, the image forming unit 10 is arranged to be inclined with respect to the normal direction perpendicular to the panel in order to obtain a wide angle of view.

導光板２０は、第１の導光板１０１と第２の導光板２０１から構成されている。第１の導光板１０１及び第２の導光板２０１の全体的な外観は、図中ＹＸ面に平行に延びる平板状の部材によって形成されている。第１の導光板１０１及び第２の導光板２０１は、ガラスあるいは光透過性の樹脂材料等により形成された板状の部材である。 The light guide plate 20 includes a first light guide plate 101 and a second light guide plate 201. The overall appearance of the first light guide plate 101 and the second light guide plate 201 is formed by a flat plate-like member extending parallel to the YX plane in the drawing. The first light guide plate 101 and the second light guide plate 201 are plate-like members formed of glass or a light-transmitting resin material.

第１の導光板１０１は、画像形成部１０に対向配置された第１のパネル面１０１ａ、及び第１のパネル面１０１ａと対向する第２のパネル面１０１ｂを有し、第１のパネル面１０１ａの一方の端部に形成された光入射面１０１ｃを通じて画像光が入射され、入射された画像光は、第１のパネル面１０１ａ及び第２のパネル面１０１ｂにより全反射され、観察者の眼前に形成された光出射面１０１ｄへ導光する。 The first light guide plate 101 includes a first panel surface 101a disposed to face the image forming unit 10, and a second panel surface 101b facing the first panel surface 101a, and the first panel surface 101a. The image light is incident through the light incident surface 101c formed at one end of the first image surface, and the incident image light is totally reflected by the first panel surface 101a and the second panel surface 101b, and in front of the observer's eyes. The light is guided to the formed light exit surface 101d.

第２の導光板２０１は、第１の導光板１０１に対向配置された第１のパネル面２０１ａ、及び第１のパネル面２０１ａと対向する第２のパネル面２０１ｂを有し、第１のパネル面２０１ａの一方の端部に形成された光入射面２０１ｃを通じて画像光が入射され、入射された画像光は、第１のパネル面２０１ａ及び第２のパネル面２０１ｂにより全反射され、第１のパネル面２０１ａの他方の端部に形成された光出射面２０１ｄへ導光する。 The second light guide plate 201 has a first panel surface 201a disposed opposite to the first light guide plate 101, and a second panel surface 201b opposed to the first panel surface 201a. The image light is incident through the light incident surface 201c formed at one end of the surface 201a, and the incident image light is totally reflected by the first panel surface 201a and the second panel surface 201b, and the first The light is guided to the light exit surface 201d formed at the other end of the panel surface 201a.

なお、第１の導光板１０１の第１及び第２のパネル面１０１ａ，１０１ｂ、及び第２の導光板２０１の第１及び第２のパネル面２０１ａ，２０１ｂには反射コートを施さず、前記パネル面１０１ａ，１０１ｂ，２０１ａ，２０１ｂに対して外界側から入射する外界光が、高い透過率で第１の導光板１０１及び第２の導光板２０１を通過するようにしてもよい。これにより、第１の導光板１０１及び第２の導光板２０１を、外界像の透視が可能なシースルータイプとすることができる。 The first and second panel surfaces 101a and 101b of the first light guide plate 101 and the first and second panel surfaces 201a and 201b of the second light guide plate 201 are not provided with a reflective coating, and the panel External light that is incident on the surfaces 101a, 101b, 201a, and 201b from the external side may pass through the first light guide plate 101 and the second light guide plate 201 with high transmittance. Thereby, the 1st light guide plate 101 and the 2nd light guide plate 201 can be made into the see-through type which can see through an external field image.

第１の導光板１０１の光入射面１０１ｃには、入射光を光出射面１０１ｄ側の端面方向に回折させる第１回折光学素子１０２が設けられ、光出射面１０１ｄには、光出射面１０１ｄから外部に向けて画像光を回折させ、虚像光として観察者の眼ＥＹに投射する第２回折光学素子１０３が設けられている。 The light incident surface 101c of the first light guide plate 101 is provided with a first diffractive optical element 102 that diffracts incident light in the direction of the end surface on the light exit surface 101d side, and the light exit surface 101d is connected to the light exit surface 101d. A second diffractive optical element 103 is provided that diffracts image light toward the outside and projects it as virtual image light onto the observer's eye EY.

第２の導光板２０１の光入射面２０１ｃには、入射光を光出射面２０１ｄ側の端面方向に回折させる第３回折光学素子２０２が設けられ、光出射面２０１ｄには、光出射面２０１ｄから外部に向けて画像光を回折させ、第１の導光板１０１を介して虚像光として観察者の眼ＥＹに投射する第４回折光学素子２０３が設けられている。 The light incident surface 201c of the second light guide plate 201 is provided with a third diffractive optical element 202 that diffracts incident light in the direction of the end surface on the light exit surface 201d side. A fourth diffractive optical element 203 that diffracts image light toward the outside and projects the image light as virtual image light onto the observer's eye EY via the first light guide plate 101 is provided.

本実施形態においては、第１回折光学素子１０２、第２回折光学素子１０３、第３回折光学素子２０２、及び第４回折光学素子２０３は、一例として、いずれも表面レリーフ型の回折格子である。 In the present embodiment, as an example, the first diffractive optical element 102, the second diffractive optical element 103, the third diffractive optical element 202, and the fourth diffractive optical element 203 are all surface relief type diffraction gratings.

（第１の導光板）
第１の導光板１０１の光入射面１０１ｃに設けられた第１回折光学素子１０２は、回折効率を高めるために、格子面が図２に示す方向に傾斜している。回折光を入射光の中心軸に近い方から０次、±１次...と順序づけていくと、図３に示すように傾斜なしの矩形形状の表面レリーフ型の回折格子の場合は、＋１次の回折光と−１次の回折光はほぼ同じ強度となる。 (First light guide plate)
In the first diffractive optical element 102 provided on the light incident surface 101c of the first light guide plate 101, the grating surface is inclined in the direction shown in FIG. 2 in order to increase the diffraction efficiency. When the diffracted light is ordered in the order of 0th order, ± 1st order,... From the side closer to the central axis of the incident light, as shown in FIG. The next diffracted light and the −1st order diffracted light have substantially the same intensity.

しかし、表面レリーフ型の回折格子の格子面を傾斜させた場合には、格子面の傾斜と入射光の方向が図４に示すような関係にあると、格子面上でのブラッグ反射により回折光が発生するため、＋１次の回折光の強度が、−１次の回折光の強度よりも高くなる。その結果、画像光を光出射面に向けて伝播する方向に回折される光に対する回折効率を高めることができる。 However, when the grating surface of the surface relief type diffraction grating is inclined, if the inclination of the grating surface and the direction of incident light are in a relationship as shown in FIG. 4, the diffracted light is caused by Bragg reflection on the grating surface. Therefore, the intensity of the + 1st order diffracted light becomes higher than the intensity of the −1st order diffracted light. As a result, it is possible to increase the diffraction efficiency for light diffracted in the direction in which image light propagates toward the light exit surface.

第１の導光板１０１の光出射面１０１ｄに設けられた第２回折光学素子１０３は、図２に示すように、格子面は傾斜していない。しかし、第２回折光学素子１０３は、図２に示すように、回折格子の深さが段階的に変化しており、第１の導光板１０１の光出射面１０１ｄ側の端面に近くなるほど、深くなっている。詳しくは後述する。 As shown in FIG. 2, the grating surface of the second diffractive optical element 103 provided on the light exit surface 101d of the first light guide plate 101 is not inclined. However, as shown in FIG. 2, the second diffractive optical element 103 has a diffraction grating whose depth changes stepwise, and becomes deeper as it approaches the end surface of the first light guide plate 101 on the light exit surface 101 d side. It has become. Details will be described later.

なお、第２回折光学素子１０３が出射させる光は、画像光１３と同じ角度にする必要があるので、第１回折光学素子１０２と第２回折光学素子１０３の格子周期（図２におけるＸ方向の周期）は同一となっている。 Since the light emitted from the second diffractive optical element 103 needs to have the same angle as the image light 13, the grating period of the first diffractive optical element 102 and the second diffractive optical element 103 (in the X direction in FIG. 2) The period) is the same.

図２に示すように、回折格子による回折角度は、波長によって異なり、波長が短いほど回折角度が小さい。したがって、第１回折光学素子１０２によって第１の導光板１０１に導入される角度は、青色光１３Ｂ、緑色光１３Ｇ、及び赤色光１３Ｒによって異なっている。本実施形態では、青色光１３Ｂが広い入射角度範囲に亘って第１の導光板１０１内を全反射で伝播できるように、第１回折光学素子１０２の格子周期が決められている。このように構成すると、赤色光１３Ｒに対する回折角は大きくなり、赤色光１３Ｒに対する回折効率は大きく低下する。したがって、第１の導光板１０１は、実質的に青色光１３Ｂと緑色光１３Ｇが伝播される。 As shown in FIG. 2, the diffraction angle by the diffraction grating varies depending on the wavelength, and the shorter the wavelength, the smaller the diffraction angle. Therefore, the angle introduced into the first light guide plate 101 by the first diffractive optical element 102 differs depending on the blue light 13B, the green light 13G, and the red light 13R. In the present embodiment, the grating period of the first diffractive optical element 102 is determined so that the blue light 13B can propagate through the first light guide plate 101 over a wide incident angle range. If comprised in this way, the diffraction angle with respect to red light 13R will become large, and the diffraction efficiency with respect to red light 13R will fall large. Therefore, the first light guide plate 101 substantially propagates the blue light 13B and the green light 13G.

第１の導光板１０１内で全反射を繰り返しながら伝播した光は、第２回折光学素子１０３に到達し、回折格子面に入射するたびに少しずつ取り出されて観察者の眼ＥＹに到達する。波長が短い青色光１３Ｂは、第１の導光板１０１内を小さな角度（立った角度）で伝播し、第２回折光学素子１０３が設けられている領域においては、第２回折光学素子１０３に入射する回数が、緑色光１３Ｇ、赤色光１３Ｒに比べて多くなる。図２では、青色光１３Ｂが第２回折光学素子１０３に５回入射する例を示している。 The light propagated while repeating total reflection in the first light guide plate 101 reaches the second diffractive optical element 103 and is taken out little by little every time it enters the diffraction grating surface and reaches the eye EY of the observer. The blue light 13B having a short wavelength propagates through the first light guide plate 101 at a small angle (standing angle), and enters the second diffractive optical element 103 in the region where the second diffractive optical element 103 is provided. The number of times to perform increases compared to the green light 13G and the red light 13R. FIG. 2 shows an example in which the blue light 13B is incident on the second diffractive optical element 103 five times.

（第２回折光学素子）
図５に第２回折光学素子１０３が設けられた部分を拡大して示す。図５に示すように、第２回折光学素子１０３は、５つの領域１０３Ａ，１０３Ｂ，１０３Ｃ，１０３Ｄ，１０３Ｅに分割されおり、それぞれの領域で回折格子の深さが異なっている。第１回折光学素子１０２から見て最も遠い領域１０３Ｅにおける回折格子の深さが最も深く、領域１０３Ｅにおける回折格子の深さは、第１の導光板１０１内を小さな角度で伝播してくる青色光１３Ｂに対して、１次回折効率が最大となる深さとなっている。そして、回折格子の深さは、領域１０３Ｄ，１０３Ｃ，１０３Ｂ，１０３Ａと第１回折光学素子１０２に近くなるほど、段階的に回折格子の深さが浅くなっている。 (Second diffractive optical element)
FIG. 5 shows an enlarged portion where the second diffractive optical element 103 is provided. As shown in FIG. 5, the second diffractive optical element 103 is divided into five regions 103A, 103B, 103C, 103D, and 103E, and the depth of the diffraction grating is different in each region. The depth of the diffraction grating in the region 103E farthest from the first diffractive optical element 102 is the deepest, and the depth of the diffraction grating in the region 103E is blue light that propagates through the first light guide plate 101 at a small angle. For 13B, the depth is such that the first-order diffraction efficiency is maximized. As the depth of the diffraction grating becomes closer to the regions 103D, 103C, 103B, and 103A and the first diffractive optical element 102, the depth of the diffraction grating becomes gradually smaller.

図６に示すように、全体が同じ深さの第２回折光学素子１０３'を第１の導光板１０１に設けたとすると、第１回折光学素子１０２に最も近い領域１０３Ａで多くの光が取り出され、第１回折光学素子１０２から最も遠い領域１０３Ｅまで到達する光量が減少してしまう。 As shown in FIG. 6, when the second diffractive optical element 103 ′ having the same depth as a whole is provided on the first light guide plate 101, much light is extracted in the region 103 </ b> A closest to the first diffractive optical element 102. The amount of light reaching the farthest region 103E from the first diffractive optical element 102 is reduced.

図７に、深さが段階的に変化する第２回折光学素子１０３を用いた場合と、全体が同じ深さの第２回折光学素子１０３'を用いた場合の出射光量の比較結果を示す。図７において、曲線ａは、全体が同じ深さの第２回折光学素子１０３'を用いた場合の出射光量の分布を示す。また、曲線ｂは、深さが段階的に変化する第２回折光学素子１０３を用いた場合の出射光量の分布を示す。 FIG. 7 shows a comparison result of the amount of emitted light when the second diffractive optical element 103 whose depth changes stepwise and when the second diffractive optical element 103 ′ having the same depth as a whole is used. In FIG. 7, a curve a indicates the distribution of the emitted light amount when the second diffractive optical element 103 ′ having the same depth as a whole is used. Curve b shows the distribution of the emitted light quantity when the second diffractive optical element 103 whose depth changes stepwise is used.

図７に示すように、全体が同じ深さの第２回折光学素子１０３'を用いた場合には、第１回折光学素子１０２に最も近い領域１０３Ａで多くの光が取り出され、第１回折光学素子１０２から遠い領域になるほど、光量が減少してしまうことがわかる。 As shown in FIG. 7, when the second diffractive optical element 103 ′ having the same depth as a whole is used, a lot of light is extracted in the region 103A closest to the first diffractive optical element 102, and the first diffractive optical element It can be seen that the amount of light decreases as the area is farther from the element 102.

しかし、図７に示すように、深さが段階的に変化する第２回折光学素子１０３を用いた場合には、第１回折光学素子１０２に最も近い領域１０３Ａから、第１回折光学素子１０２から最も遠い領域１０３Ｅまで、出射光量の分布はほぼ均一となる。これは、第１回折光学素子１０２に最も近い領域１０３Ａでの回折格子を浅くして回折効率を低くしてあるため、領域１０３Ａ以降においても第１の導光体１０１内に残存している光量が増加し、第１回折光学素子１０２から最も遠い領域１０３Ｅまで光を届けることができるためである。 However, as shown in FIG. 7, when the second diffractive optical element 103 whose depth changes stepwise is used, from the region 103 </ b> A closest to the first diffractive optical element 102, from the first diffractive optical element 102. The distribution of the amount of emitted light is almost uniform up to the farthest region 103E. This is because the diffraction efficiency in the region 103A closest to the first diffractive optical element 102 is made shallow to reduce the diffraction efficiency, so that the amount of light remaining in the first light guide 101 after the region 103A is also reduced. This is because light can be delivered to the region 103E farthest from the first diffractive optical element 102.

（第２の導光板）
第１の導光板１０１の第１回折光学素子１０２で回折されずに透過した光２３は、第２の導光板２０１の光入射面２０１ｃに設けられた第３回折光学素子２０２に入射する。第３回折光学素子２０２に入射した光は、回折されて第２の導光板２０１に導入される。 (Second light guide plate)
The light 23 transmitted without being diffracted by the first diffractive optical element 102 of the first light guide plate 101 enters a third diffractive optical element 202 provided on the light incident surface 201 c of the second light guide plate 201. The light incident on the third diffractive optical element 202 is diffracted and introduced into the second light guide plate 201.

第２の導光板２０１の光入射面２０１ｃに設けられた第３回折光学素子２０２は、回折効率を高めるために、格子面が図２に示す方向に傾斜している。格子面が傾斜している構成は、第１回折光学素子１０２と同様である。しかし、第３回折光学素子２０２の格子周期は、第１回折光学素子１０２の格子周期とは異なっている。このように第３回折光学素子２０２の格子周期を第１回折光学素子１０２の格子周期と異ならせたために、第１の導光板１０１内を伝播させる光と異なる波長範囲の光を第２の導光板２０１内に伝播させることができる。具体的には、第３回折光学素子２０２の格子周期は、緑色光２３Ｇが広い入射角度範囲に亘って第２の導光板２０１内を全反射で伝播できるように第１回折光学素子１０２の格子周期よりも長い格子周期に設定されている。したがって、入射角によっては、青色光に対する回折角が小さくなり、第２の導光板２０１と空気の界面で全反射されずに第２の導光板２０１を透過してしまう。その結果、第２の導光板２０１では、実質的に緑色光２３Ｇと赤色光２３Ｒが伝播されることになる。 The third diffractive optical element 202 provided on the light incident surface 201c of the second light guide plate 201 is inclined in the direction shown in FIG. 2 in order to increase the diffraction efficiency. The configuration in which the grating surface is inclined is the same as that of the first diffractive optical element 102. However, the grating period of the third diffractive optical element 202 is different from the grating period of the first diffractive optical element 102. Since the grating period of the third diffractive optical element 202 is made different from the grating period of the first diffractive optical element 102 in this way, light having a wavelength range different from that of the light propagating through the first light guide plate 101 is transmitted to the second guide. It can be propagated into the light plate 201. Specifically, the grating period of the third diffractive optical element 202 is such that the green light 23G can propagate through the second light guide plate 201 with total reflection over a wide incident angle range. The grating period is set longer than the period. Accordingly, depending on the incident angle, the diffraction angle with respect to the blue light becomes small, and the second light guide plate 201 is transmitted without being totally reflected at the interface between the second light guide plate 201 and the air. As a result, in the second light guide plate 201, the green light 23G and the red light 23R are substantially propagated.

第２の導光板２０１の光出射面２０１ｄに設けられた第４回折光学素子２０３は、第３回折光学素子２０２と同様に、回折効率を高めるために、格子面が図２に示す方向に傾斜している。詳しくは後述する。 As with the third diffractive optical element 202, the fourth diffractive optical element 203 provided on the light exit surface 201d of the second light guide plate 201 is inclined in the direction shown in FIG. 2 in order to increase the diffraction efficiency. doing. Details will be described later.

なお、第４回折光学素子２０３が出射させる光は、画像光２３と同じ角度にする必要があるので、第３回折光学素子２０２と第４回折光学素子２０３の格子周期（図２におけるＸ方向の周期）は同一となっている。 The light emitted from the fourth diffractive optical element 203 needs to have the same angle as that of the image light 23, and therefore the grating period of the third diffractive optical element 202 and the fourth diffractive optical element 203 (in the X direction in FIG. 2). The period) is the same.

第２の導光板２０１では、緑色光２３Ｇと赤色光２３Ｒが伝播されるが、その中でも赤色光２３Ｒを高い効率で伝播させることが重要となる。これは、緑色光は第１の導光板１０１でも伝播されるためである。 In the second light guide plate 201, the green light 23G and the red light 23R are propagated. Among them, it is important to propagate the red light 23R with high efficiency. This is because green light is propagated also in the first light guide plate 101.

波長が長い赤色光２３Ｒは、第３回折光学素子２０２によって大きな角度で回折されるため、第２の導光板２０１内部を大きな角度で伝播する。したがって、第４回折光学素子２０３が設けられている領域においては、第４回折光学素子２０３に入射する回数が少ない。図２では、赤色光２３Ｒが第４回折光学素子２０３に２回入射する例を示している。 Since the red light 23R having a long wavelength is diffracted by the third diffractive optical element 202 at a large angle, the red light 23R propagates through the second light guide plate 201 at a large angle. Accordingly, in the region where the fourth diffractive optical element 203 is provided, the number of times of incidence on the fourth diffractive optical element 203 is small. FIG. 2 shows an example in which the red light 23R enters the fourth diffractive optical element 203 twice.

（第４回折光学素子）
このように、第４回折光学素子２０３に入射する回数が少ない場合には、第２回折光学素子１０３のように、複数の領域に分割して入射側の回折光学素子に近い領域の回折効率を低くしても、出射光量の分布を均一化する効果は少なく、出射される光量が低下して観察される虚像が暗くなる場合がある。 (Fourth diffractive optical element)
As described above, when the number of times of incidence on the fourth diffractive optical element 203 is small, the diffraction efficiency of the region close to the incident side diffractive optical element is divided into a plurality of regions as in the second diffractive optical element 103. Even if it is lowered, there is little effect of making the distribution of the emitted light quantity uniform, and the observed virtual image may become darker as the emitted light quantity decreases.

そこで、本実施形態においては、図８に示すように、第４回折光学素子２０３の格子面を傾斜させ、傾斜型表面レリーフ回折格子とすることで、出射光量を増加させている。 Therefore, in the present embodiment, as shown in FIG. 8, the amount of emitted light is increased by inclining the grating surface of the fourth diffractive optical element 203 to form an inclined surface relief diffraction grating.

（回折光学素子の位置関係）
図９に示すように、第１の導光板１０１の第１回折光学素子１０２に入射する光の光軸は、所定の角度で傾斜しているため、第２の導光板２０１の第３回折光学素子２０２の位置は、第１回折光学素子１０２に比べて第２の導光板２０１の中央部側に移動した位置になっている。 (Positional relationship of diffractive optical elements)
As shown in FIG. 9, since the optical axis of the light incident on the first diffractive optical element 102 of the first light guide plate 101 is inclined at a predetermined angle, the third diffractive optical of the second light guide plate 201 is used. The position of the element 202 is a position moved to the central portion side of the second light guide plate 201 as compared with the first diffractive optical element 102.

同様に、第１の導光板１０１の第２回折光学素子１０３から出射する光の光軸は、所定の角度で傾斜しているため、第２の導光板２０１の第４回折光学素子２０３の位置は、第１回折光学素子１０２に比べて第２の導光板２０１の中央部側に移動した位置になっている。 Similarly, since the optical axis of the light emitted from the second diffractive optical element 103 of the first light guide plate 101 is inclined at a predetermined angle, the position of the fourth diffractive optical element 203 of the second light guide plate 201 is changed. Is a position moved to the center side of the second light guide plate 201 as compared with the first diffractive optical element 102.

したがって、第１の導光板１０１の正面側から見ると、図１０に示すように、第１回折光学素子１０２と第３回折光学素子２０２、及び、第２回折光学素子１０３と第４回折光学素子２０３の位置は、第１の導光板１０１の長手方向においてずれた位置関係を有している。なお、図１０においては、各回折光学素子を枠のみで表している。各回折光学素子をこのような位置に配置することにより、入射時及び出射時における損失を低下させることができる。 Accordingly, when viewed from the front side of the first light guide plate 101, as shown in FIG. 10, the first diffractive optical element 102 and the third diffractive optical element 202, and the second diffractive optical element 103 and the fourth diffractive optical element are provided. The position 203 has a positional relationship shifted in the longitudinal direction of the first light guide plate 101. In FIG. 10, each diffractive optical element is represented by a frame only. By disposing each diffractive optical element at such a position, it is possible to reduce the loss at the time of incidence and at the time of emission.

以上説明したように、本実施形態によれば、青色光から緑色光を分担する第１の導光板１０１と、緑色光から赤色光を分担する第２の導光板２０１とに分離して導光させ、出射面１０１ｄでの反射回数が多い青色光に対しては、回折効率が領域によって異なる第２回折光学素子１０３を適用し、出射面２０１ｄでの反射回数が少ない赤色光に対しては、格子面が傾斜した第４回折光学素子２０３を適用したので、出射光量分布の不均一あるいは色ムラを抑制した虚像を表示できる画像表示装置を提供することができる。 As described above, according to this embodiment, the light is separated into the first light guide plate 101 that shares green light from the blue light and the second light guide plate 201 that shares red light from the green light. The second diffractive optical element 103 having a different diffraction efficiency depending on the region is applied to blue light having a large number of reflections on the exit surface 101d, and for red light having a small number of reflections on the exit surface 201d, Since the fourth diffractive optical element 203 having an inclined grating surface is applied, it is possible to provide an image display device that can display a virtual image in which the distribution of emitted light quantity is nonuniform or color unevenness is suppressed.

＜Ｂ：第２実施形態＞
次いで、本発明の第２実施形態について説明する。本実施形態は、第２回折光学素子１０３における回折効率を領域によって変えるために、第２回折光学素子１０３の回折格子の充填率を領域によって変更した例である。図１１は本実施形態における第２回折光学素子１０３が設けられた部分の拡大図である。図１２は回折格子の充填率を説明するための図である。 <B: Second Embodiment>
Next, a second embodiment of the present invention will be described. The present embodiment is an example in which the filling rate of the diffraction grating of the second diffractive optical element 103 is changed depending on the region in order to change the diffraction efficiency of the second diffractive optical element 103 depending on the region. FIG. 11 is an enlarged view of a portion provided with the second diffractive optical element 103 in the present embodiment. FIG. 12 is a diagram for explaining the filling factor of the diffraction grating.

図１２に示すように、回折格子の充填率とは、回折格子の格子周期に対する回折格子の幅が占める比率で、隣り合う２つの回折格子の間隔、つまり格子周期をＰ、回折格子の幅をＬとした時、Ｌ／Ｐで表される。 As shown in FIG. 12, the filling factor of the diffraction grating is a ratio of the width of the diffraction grating to the grating period of the diffraction grating, and the interval between two adjacent diffraction gratings, that is, the grating period is P, and the width of the diffraction grating is When L, it is expressed as L / P.

格子周期Ｐは、第２回折光学素子１０３全体に亘って同一なので、本実施形態においては、回折格子の充填率を変えるために、図１１に示すように複数の領域１０３Ａ〜１０３Ｅのそれぞれにおいて回折格子の幅を変化させた。具体的には、第１回折光学素子１０２から最も遠い領域１０３Ｅの回折格子の充填率が最も高く、領域１０３Ｄ、領域１０３Ｃ、領域１０３Ｂ、領域１０３Ａと第１回折光学素子１０２に近づくほど、回折格子の充填率を低くしている。このように構成した結果、第１回折光学素子１０２から最も遠い領域１０３Ｅの回折効率が最も高く、領域１０３Ｄ、領域１０３Ｃ、領域１０３Ｂ、領域１０３Ａと第１回折光学素子１０２に近づくほど回折効率が低下し、第１回折光学素子１０２に最も近い領域１０３Ａで最も回折効率が低くなっている。 Since the grating period P is the same throughout the second diffractive optical element 103, in this embodiment, in order to change the filling factor of the diffraction grating, diffraction is performed in each of the plurality of regions 103A to 103E as shown in FIG. The width of the lattice was changed. Specifically, the filling rate of the diffraction grating in the region 103E farthest from the first diffractive optical element 102 is the highest, and the closer to the region 103D, the region 103C, the region 103B, the region 103A and the first diffractive optical element 102, the closer to the diffraction grating The filling rate is low. As a result of such a configuration, the diffraction efficiency of the region 103E farthest from the first diffractive optical element 102 is highest, and the diffraction efficiency decreases as the region 103D, region 103C, region 103B, region 103A and the first diffractive optical element 102 are closer to each other. The diffraction efficiency is lowest in the region 103A closest to the first diffractive optical element 102.

本実施形態によれば、青色光から緑色光を分担する第１の導光板１０１と、緑色光から赤色光を分担する第２の導光板２０１とに分離して導光させ、出射面１０１ｄでの反射回数が多い青色光に対しては、回折効率が領域によって異なる第２回折光学素子１０３を適用し、出射面２０１ｄでの反射回数が少ない赤色光に対しては、格子面が傾斜した第４回折光学素子２０３を適用したので、出射光量分布の不均一あるいは色ムラを抑制した虚像を表示できる画像表示装置を提供することができる。 According to this embodiment, the first light guide plate 101 that shares green light from blue light and the second light guide plate 201 that shares red light from green light are separated and guided, and the light exit surface 101d The second diffractive optical element 103 having a different diffraction efficiency depending on the region is applied to the blue light having a large number of reflections of the light, and the red light having a small number of reflections on the exit surface 201d is applied with the inclined grating surface. Since the four-diffractive optical element 203 is applied, it is possible to provide an image display device capable of displaying a virtual image in which the distribution of the emitted light quantity is not uniform or the color unevenness is suppressed.

＜Ｃ：第３実施形態＞
次いで、本発明の第３実施形態について説明する。本実施形態は、第２回折光学素子１０３における回折効率を領域によって変えるために、第２回折光学素子１０３の回折格子の深さを領域によって変更すると共に、回折格子を傾斜させた例である。図１３は本実施形態における第２回折光学素子１０３が設けられた部分の拡大図である。 <C: Third Embodiment>
Next, a third embodiment of the present invention will be described. In this embodiment, in order to change the diffraction efficiency in the second diffractive optical element 103 depending on the region, the depth of the diffraction grating of the second diffractive optical element 103 is changed depending on the region, and the diffraction grating is inclined. FIG. 13 is an enlarged view of a portion provided with the second diffractive optical element 103 in the present embodiment.

図１３に示すように、第１回折光学素子１０２から最も遠い領域１０３Ｅの回折格子の深さが最も深く、第１の導光板１０１内を小さな角度で伝播してくる青色光１３Ｂに対して、１次回折効率が最大となる深さとなっている。そして、回折格子の深さは、領域１０３Ｄ，１０３Ｃ，１０３Ｂ，１０３Ａと第１回折光学素子１０２に近くなるほど、段階的に回折格子の深さが浅くなっている。このように構成した結果、第１回折光学素子１０２から最も遠い領域１０３Ｅの回折効率が最も高く、領域１０３Ｄ、領域１０３Ｃ、領域１０３Ｂ、領域１０３Ａと第１回折光学素子１０２に近づくほど回折効率が低下し、第１回折光学素子１０２に最も近い領域１０３Ａで最も回折効率が低くなっている。 As shown in FIG. 13, for the blue light 13B that has the deepest diffraction grating in the region 103E farthest from the first diffractive optical element 102 and propagates in the first light guide plate 101 at a small angle, The depth is such that the first-order diffraction efficiency is maximized. As the depth of the diffraction grating becomes closer to the regions 103D, 103C, 103B, and 103A and the first diffractive optical element 102, the depth of the diffraction grating becomes gradually smaller. As a result of such a configuration, the diffraction efficiency of the region 103E farthest from the first diffractive optical element 102 is highest, and the diffraction efficiency decreases as the region 103D, region 103C, region 103B, region 103A and the first diffractive optical element 102 are closer to each other. The diffraction efficiency is lowest in the region 103A closest to the first diffractive optical element 102.

さらに、本実施形態においては、第２回折光学素子１０３の回折格子を図１３に示すように傾斜させている。その結果、第２回折光学素子１０３から出射される光の光量を増加させることができる。 Furthermore, in this embodiment, the diffraction grating of the second diffractive optical element 103 is inclined as shown in FIG. As a result, the amount of light emitted from the second diffractive optical element 103 can be increased.

＜Ｄ：第４実施形態＞
次いで、本発明の第４実施形態について説明する。本実施形態は、第２回折光学素子１０３における回折効率を領域によって変えるために、第２回折光学素子１０３の回折格子の充填率を領域によって変更すると共に、回折格子を傾斜させた例である。図１４は本実施形態における第２回折光学素子１０３が設けられた部分の拡大図である。 <D: Fourth Embodiment>
Next, a fourth embodiment of the present invention will be described. In this embodiment, in order to change the diffraction efficiency in the second diffractive optical element 103 depending on the region, the filling rate of the diffraction grating of the second diffractive optical element 103 is changed depending on the region, and the diffraction grating is inclined. FIG. 14 is an enlarged view of a portion provided with the second diffractive optical element 103 in the present embodiment.

本実施形態では、図１４に示すように複数の領域１０３Ａ〜１０３Ｅのそれぞれにおいて回折格子の幅を変化させ、回折格子の充填率を変化させた。具体的には、第１回折光学素子１０２から最も遠い領域１０３Ｅの回折格子の充填率が最も高く、領域１０３Ｄ、領域１０３Ｃ、領域１０３Ｂ、領域１０３Ａと第１回折光学素子１０２に近づくほど、回折格子の充填率を低くしている。このように構成した結果、第１回折光学素子１０２から最も遠い領域１０３Ｅの回折効率が最も高く、領域１０３Ｄ、領域１０３Ｃ、領域１０３Ｂ、領域１０３Ａと第１回折光学素子１０２に近づくほど回折効率が低下し、第１回折光学素子１０２に最も近い領域１０３Ａで最も回折効率が低くなっている。 In this embodiment, as shown in FIG. 14, the width of the diffraction grating is changed in each of the plurality of regions 103A to 103E, and the filling factor of the diffraction grating is changed. Specifically, the filling rate of the diffraction grating in the region 103E farthest from the first diffractive optical element 102 is the highest, and the closer to the region 103D, the region 103C, the region 103B, the region 103A and the first diffractive optical element 102, the closer to the diffraction grating The filling rate is low. As a result of such a configuration, the diffraction efficiency of the region 103E farthest from the first diffractive optical element 102 is highest, and the diffraction efficiency decreases as the region 103D, region 103C, region 103B, region 103A and the first diffractive optical element 102 are closer to each other. The diffraction efficiency is lowest in the region 103A closest to the first diffractive optical element 102.

＜Ｅ：変形例＞
上述した第１実施形態〜第４実施形態では、入射側の回折光学素子である第１回折光学素子１０２，第３回折光学素子２０２として、表面レリーフ型の回折格子を用いたが、これに限定されるものではなく、体積ホログラム、ミラー、あるいはプリズム等の光学素子を用いることも可能である。また、第１実施形態〜第４実施形態では、第１回折光学素子１０２，第３回折光学素子２０２，第４回折光学素子２０３として、傾斜型の表面レリーフ回折格子を用いる例について説明したが、ブレーズ型回折格子を適用することも可能である。 <E: Modification>
In the first to fourth embodiments described above, surface relief type diffraction gratings are used as the first diffractive optical element 102 and the third diffractive optical element 202 which are diffractive optical elements on the incident side. However, the present invention is not limited to this. However, it is also possible to use an optical element such as a volume hologram, a mirror, or a prism. In the first to fourth embodiments, an example in which an inclined surface relief diffraction grating is used as the first diffractive optical element 102, the third diffractive optical element 202, and the fourth diffractive optical element 203 has been described. It is also possible to apply a blazed diffraction grating.

さらに、上述した第１実施形態〜第４実施形態では、便宜的に、第２回折光学素子１０３を５つの領域に分割した例について説明したが、さらに分割数を多くするようにしてもよい。あるいは、領域ごとに回折格子の深さや回折格子の充填率を変更するのではなく、連続的に回折格子の深さや回折格子の充填率を変化させるように構成することも可能である。 Furthermore, in the above-described first to fourth embodiments, the example in which the second diffractive optical element 103 is divided into five regions has been described for convenience. However, the number of divisions may be further increased. Alternatively, instead of changing the depth of the diffraction grating and the filling rate of the diffraction grating for each region, it is possible to continuously change the depth of the diffraction grating and the filling rate of the diffraction grating.

１０…画像形成部、１１…画像表示装置、１２…投射光学系、１３…画像光、１３Ｂ…青色光、１３Ｇ…緑色光、１３Ｒ…赤色光、２０…導光板、２３…画像光、２３Ｇ…緑色光、２３Ｒ…赤色光、１００…ヘッドマウントディスプレイ、１００Ａ，１００Ｂ…表示装置、１０１…第１導光板、１０１ａ，１０１ｂ…パネル面、１０１ｃ…第１光入射面、１０１ｄ…第１光出射面、１０２…第１回折光学素子、１０３…第２回折光学素子、１０３Ａ，１０３Ｂ，１０３Ｃ，１０３Ｄ，１０３Ｅ…領域、１１１，１１２…画像形成装置、１３１，１３２…テンプル、２０１…第２導光板、２０１ａ，２０１ｂ…パネル面、２０１ｃ…第２光入射面、２０１ｄ…第２光出射面、２０２…第３回折光学素子、２０３…第４回折光学素子。
DESCRIPTION OF SYMBOLS 10 ... Image formation part, 11 ... Image display apparatus, 12 ... Projection optical system, 13 ... Image light, 13B ... Blue light, 13G ... Green light, 13R ... Red light, 20 ... Light guide plate, 23 ... Image light, 23G ... Green light, 23R ... red light, 100 ... head mounted display, 100A, 100B ... display device, 101 ... first light guide plate, 101a, 101b ... panel surface, 101c ... first light incident surface, 101d ... first light emitting surface , 102 ... 1st diffractive optical element, 103 ... 2nd diffractive optical element, 103A, 103B, 103C, 103D, 103E ... area, 111, 112 ... image forming apparatus, 131, 132 ... temple, 201 ... 2nd light guide plate, 201a, 201b ... panel surface, 201c ... second light incident surface, 201d ... second light exit surface, 202 ... third diffractive optical element, 203 ... fourth diffractive optical element.

Claims

第１光入射部と第１光出射部とを備えた第１導光体と、
第２光入射部と第２光出射部とを備えた第２導光体と、
前記第２導光体の前記第２光出射部に設けられ、前記第２導光体の内部を導光した光の少なくとも一部を回折させて前記第２導光体の外部に取り出す第１回折光学素子と、
前記第１導光体の前記第１光出射部に設けられ、前記第１導光体の内部を導光した光の少なくとも一部及び前記第１回折光学素子で取り出された光の少なくとも一部を取り出す第２回折光学素子と、を有し、
前記第１導光体及び前記第２導光体に入射する入射光は、一部が前記第１光入射部から前記第１導光体の内部に入射して導光され、他の一部が前記第２光入射部から前記第２導光体の内部に入射して導光され、
前記第２導光体の内部を導光する光は、前記第１導光体の内部を導光する光よりも長波長の光を多く含み、
前記第２回折光学素子は、前記第１光入射部に近い側と、前記第１光入射部から遠い側とで、回折効率が異なる部分を含み、
前記第１回折光学素子は、回折効率がほぼ一定であることを特徴とする光学デバイス。 A first light guide including a first light incident portion and a first light emitting portion;
A second light guide including a second light incident portion and a second light emitting portion;
A first light provided at the second light emitting portion of the second light guide and diffracting at least a part of the light guided inside the second light guide to be taken out of the second light guide. A diffractive optical element;
At least a part of the light that is provided in the first light emitting part of the first light guide and guided through the inside of the first light guide and at least a part of the light extracted by the first diffractive optical element A second diffractive optical element for taking out
A part of the incident light incident on the first light guide and the second light guide is incident on the inside of the first light guide from the first light incident part, and is guided to the other part. Is incident on the inside of the second light guide from the second light incident part, is guided,
The light that guides the inside of the second light guide includes more light having a longer wavelength than the light that guides the inside of the first light guide,
The second diffractive optical element includes a portion where the diffraction efficiency is different between a side closer to the first light incident part and a side far from the first light incident part,
The optical device according to claim 1, wherein the first diffractive optical element has substantially constant diffraction efficiency.

請求項１に記載の光学デバイスにおいて、
前記第１回折光学素子は、一方の面に第１凹凸構造を備えた表面レリーフ型の回折格子であり、前記第２導光体の前記第２光入射部と前記第２光出射部との両方を含む断面視において、前記第1凹凸構造の凸部を構成する面のうち前記第２光出射部と交差する面が、前記第２光出射部に垂直な方向に対して傾斜していることを特徴とする光学デバイス。 The optical device according to claim 1.
The first diffractive optical element is a surface relief type diffraction grating having a first concavo-convex structure on one surface, and includes a second light incident part and a second light output part of the second light guide. In a cross-sectional view including both, a surface intersecting the second light emitting portion among the surfaces constituting the convex portion of the first concavo-convex structure is inclined with respect to a direction perpendicular to the second light emitting portion. An optical device characterized by that.

請求項１または２に記載の光学デバイスにおいて、
前記第２回折光学素子は、一方の面に第２凹凸構造を備えた表面レリーフ型の回折格子であり、前記第１導光体の前記第１光入射部と前記第１光出射部との両方を含む断面視において、前記第２凹凸構造の凸部を構成する面のうち前記第１光出射部と交差する面が、前記第１光出射部に垂直な方向に対して傾斜していることを特徴とする光学デバイス。 The optical device according to claim 1 or 2,
The second diffractive optical element is a surface relief type diffraction grating having a second concavo-convex structure on one surface, and includes the first light incident part and the first light output part of the first light guide. In a cross-sectional view including both, a surface that intersects the first light emitting portion among the surfaces constituting the convex portion of the second concavo-convex structure is inclined with respect to a direction perpendicular to the first light emitting portion. An optical device characterized by that.

請求項１または２に記載の光学デバイスにおいて、
前記第２回折光学素子は、一方の面に第２凹凸構造を備えた表面レリーフ型の回折格子であり、前記第１導光体の前記第１光入射部と前記第１光出射部との両方を含む断面視において、前記第２凹凸構造の凹部の深さが、前記第１光入射部に近い側から、前記第１光入射部から遠い側にかけて、徐々に、あるいは、段階的に変化していることを特徴とする光学デバイス。 The optical device according to claim 1 or 2,
The second diffractive optical element is a surface relief type diffraction grating having a second concavo-convex structure on one surface, and includes the first light incident part and the first light output part of the first light guide. In a cross-sectional view including both, the depth of the concave portion of the second concavo-convex structure changes gradually or stepwise from the side closer to the first light incident portion to the side farther from the first light incident portion. An optical device characterized by that.

請求項１または２に記載の光学デバイスにおいて、
前記第２回折光学素子は、一方の面に第２凹凸構造を備えた表面レリーフ型の回折格子であり、前記第１導光体の前記第１光入射部と前記第１光出射部との両方を含む断面視において、前記第２凹凸構造の充填率が、前記第１光入射部に近い側から、前記第１光入射部から遠い側にかけて、徐々に、あるいは、段階的に変化していることを特徴とする光学デバイス。 The optical device according to claim 1 or 2,
The second diffractive optical element is a surface relief type diffraction grating having a second concavo-convex structure on one surface, and includes the first light incident part and the first light output part of the first light guide. In a cross-sectional view including both, the filling factor of the second concavo-convex structure changes gradually or stepwise from the side closer to the first light incident part to the side farther from the first light incident part. An optical device.

請求項４または５に記載の光学デバイスにおいて、
前記第２回折光学素子は、前記第１導光体の前記第１光入射部と前記第１光出射部との両方を含む断面視において、前記第２凹凸構造の凸部を構成する面のうち前記第１光出射部と交差する面が、前記第１光出射部に垂直な方向に対して傾斜していることを特徴とする光学デバイス。 The optical device according to claim 4 or 5,
The second diffractive optical element has a surface constituting a convex portion of the second concavo-convex structure in a cross-sectional view including both the first light incident portion and the first light emitting portion of the first light guide. Among these, the optical device is characterized in that a surface intersecting with the first light emitting portion is inclined with respect to a direction perpendicular to the first light emitting portion.

請求項１乃至６の何れかに記載の光学デバイスにおいて、
前記第１導光体の前記第１光入射部に設けられ、前記入射光の一部を回折させて前記第１導光体の内部に入射させる第３回折光学素子と、
前記第２導光体の前記第２光入射部に設けられ、前記入射光の他の一部を回折させて前記第２導光体の内部に入射させる第４回折光学素子と、を有することを特徴とする光学デバイス。 The optical device according to any one of claims 1 to 6,
A third diffractive optical element that is provided in the first light incident portion of the first light guide and diffracts a part of the incident light to enter the first light guide;
A fourth diffractive optical element provided at the second light incident portion of the second light guide and diffracting another part of the incident light to be incident on the second light guide. An optical device characterized by.

請求項７に記載の光学デバイスにおいて、
前記第３回折光学素子の格子周期は、前記第４回折光学素子の格子周期と異なる格子周期であり、かつ、前記第２回折光学素子の格子周期と同じ格子周期であり、
前記第４回折光学素子の格子周期は、前記第１回折光学素子の格子周期と同じ格子周期であることを特徴とする光学デバイス。 The optical device according to claim 7.
The grating period of the third diffractive optical element is a grating period different from the grating period of the fourth diffractive optical element, and is the same as the grating period of the second diffractive optical element,
The optical device according to claim 4, wherein a grating period of the fourth diffractive optical element is the same as a grating period of the first diffractive optical element.

請求項８に記載の光学デバイスにおいて、
前記第３回折光学素子の格子周期は、前記第４回折光学素子の格子周期よりも短い格子周期であることを特徴とする光学デバイス。 The optical device according to claim 8.
An optical device, wherein the grating period of the third diffractive optical element is a grating period shorter than the grating period of the fourth diffractive optical element.

請求項７乃至９の何れかに記載の光学デバイスにおいて、
前記第３回折光学素子は、一方の面に第３凹凸構造を備えた表面レリーフ型の回折格子であり、前記第１導光体の前記第１光入射部と前記第１光出射部との両方を含む断面視において、前記第３凹凸構造の凸部を構成する面のうち前記第１光入射部と交差する面が、前記第１光入射部に垂直な方向に対して傾斜し、
前記第４回折光学素子は、一方の面に第４凹凸構造を備えた表面レリーフ型の回折格子であり、前記第２導光体の前記第２光入射部と前記第２光出射部との両方を含む断面視において、前記第４凹凸構造の凸部を構成する面のうち前記第２光入射部と交差する面が、前記第２光入射部に垂直な方向に対して傾斜していることを特徴とする光学デバイス。 The optical device according to any one of claims 7 to 9,
The third diffractive optical element is a surface relief type diffraction grating having a third concavo-convex structure on one surface, and includes a first light incident portion and a first light emitting portion of the first light guide. In a cross-sectional view including both, a surface that intersects the first light incident portion among the surfaces constituting the convex portion of the third uneven structure is inclined with respect to a direction perpendicular to the first light incident portion,
The fourth diffractive optical element is a surface relief type diffraction grating having a fourth concavo-convex structure on one surface, and includes the second light incident portion and the second light emitting portion of the second light guide. In a cross-sectional view including both, a surface that intersects the second light incident portion among the surfaces constituting the convex portion of the fourth concavo-convex structure is inclined with respect to a direction perpendicular to the second light incident portion. An optical device characterized by that.

請求項７乃至１０の何れかに記載の光学デバイスにおいて、
前記第４回折光学素子は、前記第２光入射部に垂直な方向から見た平面視において、前記第３回折光学素子よりも前記第２光出射部側に位置し、
前記第１回折光学素子は、前記第２光出射部に垂直な方向から見た平面視において、前記第２回折光学素子よりも前記第２光入射部側に位置していることを特徴とする光学デバイス。 The optical device according to any one of claims 7 to 10,
The fourth diffractive optical element is located closer to the second light emitting part than the third diffractive optical element in a plan view as viewed from a direction perpendicular to the second light incident part;
The first diffractive optical element is located closer to the second light incident part than the second diffractive optical element in a plan view as viewed from a direction perpendicular to the second light emitting part. Optical device.

請求項１乃至１１の何れかに記載の光学デバイスと画像光を発する画像形成部とを備えたことを特徴とする画像表示装置。
An image display apparatus comprising: the optical device according to claim 1; and an image forming unit that emits image light.