WO2015185837A1 - Dispositif optique pour l'observation d'un objet, minimisant le phenomene de reflexion interne - Google Patents
Dispositif optique pour l'observation d'un objet, minimisant le phenomene de reflexion interne Download PDFInfo
- Publication number
- WO2015185837A1 WO2015185837A1 PCT/FR2015/051433 FR2015051433W WO2015185837A1 WO 2015185837 A1 WO2015185837 A1 WO 2015185837A1 FR 2015051433 W FR2015051433 W FR 2015051433W WO 2015185837 A1 WO2015185837 A1 WO 2015185837A1
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- WIPO (PCT)
- Prior art keywords
- optical element
- optical
- lens
- objective according
- rear surface
- Prior art date
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Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B9/00—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -
- G02B9/12—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having three components only
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/20—Filters
- G02B5/22—Absorbing filters
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/0018—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 with means for preventing ghost images
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/02—Objectives
Definitions
- the present invention is applicable to the production of optical elements used in microscopic or conoscopic-type objectives and to the resolution of a drawback inherent in current production methods, observed mainly when the angular field or the numerical aperture of these goals becomes important.
- optical solutions used in the production of objectives of the "microscope" type and in particular when the numerical aperture is large, are commonly used and for the lenses close to the object to be observed or measured convergent lenses of the meniscus type , convex and more rarely biconvex, which can go for their convex part oriented towards the image plane to the hemisphere.
- Different converging lenses are shown on the first line of FIG. 1, while different diverging type lenses are shown on the second line of this FIG.
- This type of convergent lens is also used in a similar way in other types of equipment, in particular flow metrology or conoscopy.
- Such a convergent lens can be constituted as follows:
- glasses used in optics have a refractive index of between 1.4 and 1.95.
- the revolutions axes of the first and second surfaces coincide with the optical axis of the lens.
- the geometric properties (Curvature radius) of these surfaces are such that the resulting lens is convergent (Focal positive).
- the incident light emitted by the sample may, due to this phenomenon, be perfectly returned to the sample, thus causing parasitic reflections compromise the observation of the latter or the accuracy of the measurement.
- the critical angle is very low (of the order of 33 ° with the glass of the type S-LAH65 of index 1.8 to 546 nm) as can be seen in the numerical simulation of Figure 2.
- This simulation is given as an example, the same type of phenomenon can be observed regardless of the material used (Here the brand glass Ohara and reference S-LAH65).
- This phenomenon may have important consequences for the properties of convergent lenses.
- the simulation result of the reflected intensity in the plane of the object shows that for an incoming flux of lW / cm 2 , the reflected intensity can reach 2.4 W / cm 2 .
- Anti-reflective treatments can not therefore provide satisfactory solution.
- Another possible solution is to limit the radii of curvature of the lenses so as to use only angles below the critical angle causing a total internal reflection.
- the retro-reflective flux goes from 5.2 W to almost 12 mW, a reduction of a factor of 400.
- the problem that must be solved is therefore to significantly reduce the level of retro-reflections inherent to this type of lens so as to ensure that the angular and spatial distribution of light from a device under test is not disturbed by the presence of the analysis system and more particularly the convergent optical element or elements placed at the input of the latter.
- this object is achieved by the invention which relates to an optical device for the observation of an object, comprising at least a first optical element of the lens type, defining a front surface oriented towards the object to be observed and a rear surface opposite to said object. object, said first optical element being made of an optically transparent material and having a refractive index "ni".
- this device comprises a second element optical lens of a predetermined thickness, defining a front surface facing the object and a rear surface opposite to the object, and being optically coupled by its front surface to the rear surface of the first optical element, said second optical element being made of a material of refractive index n2 and provided with at least a portion made of a material optically absorbing visible light.
- the invention may furthermore include one or both of the following aspects, including:
- a second optical element of a predetermined thickness defining a front surface oriented towards the object and a rear surface opposite to the object, and being optically coupled by its front surface to the rear surface of the first optical element, said second an optical element being made of a material of refractive index n2 and provided with at least one portion made of a material optically absorbing visible light,
- the portion of the second optical element made of an optically absorbing material is the portion of the second optical element most likely to be the seat of total internal reflections
- the whole of the second optical element is made of an optical absorbent material
- the optical absorbing material constituting the second optical element is neutral
- the refractive index n2 of the second optical element is smaller than the refractive index and the first optical material
- the rear surface of the first optical element is convex and the second optical element has the shape of a cap
- the thickness of the cap is constant ,
- the indices n1 and n2 of the constituent materials of the first and second optical elements are between 1.43 and 1.96, the transmission coefficient of the absorbent material constituting the second element is between 1 and 99%,
- the minimum thickness of the second optical element is chosen to be greater than the coherence length of the light emitted or reflected by the observed object in the material used.
- the invention also relates to a microscopic type objective, comprising an optical system for transport and magnification comprising a lens or several successive lenses, and a field lens, capable of producing an image of the object observed in the image plane. , comprising at least one device that is substituted for the lens of the optical system or at least the lens of the optical system closest to the observed object, among said successive lenses of the optical system.
- the invention furthermore relates to a conoscopic-type objective, comprising a magnifying optical system comprising a lens or several successive lenses, making it possible to produce an image of the angular distribution of the observed object's flux, which is a substitute for the lens of the object. optical system or at least the lens of the optical system closest to the observed object, among said successive lenses of the optical system.
- 1 / invention also relates to an optical instrument comprising a lens of the above type.
- FIG. 1 represents different structures of convergent and divergent lenses
- FIGS. 2 and 3 above represent graphs illustrating the evolution of the internal reflection coefficient of S-LAH65 at 550 nm as a function of the angle of incidence, and highlighting the critical angle from which total reflection can be observed, without antireflection treatment of the glass in question (figure
- FIGS. 4 to 6 show a schematic view:
- FIG. 4 a convergent lens traversed by an incident ray (solid line) and subjecting another ray to a double internal total reflection (dashed lines),
- FIG. 5 a simulation of the behavior of the lens with an extended source, highlighting an annular peripheral portion of the lens more subject to internal reflections,
- figure 6 this same simulation with however a decrease of the diameter of the diopter.
- FIG. 7 represents an optical device according to the invention comprising two optically coupled elements making it possible to reduce the phenomenon of internal reflection
- FIG. 8 illustrates the optical device according to the invention associated with an optical system
- FIG. 9 illustrates the optical device according to the invention in a microscope-type instrument
- FIG. 10 illustrates the optical device according to the invention in a conoscope-type instrument
- FIG. 11 shows four graphs that can be used to size a parameter of the device according to the invention (refractive index of the shell).
- the invention is based on the introduction of a "shell" of absorbent material 2 contiguous to the outer diopter of a lens 1 of an object for observing an object, such as a lens microscope, conoscope used in the field including metrology.
- an objective of observation of an object (located on the left in this FIG. 7, and corresponding to the "before" orientation in the rest of the text), conventionally comprises at least one lens 1 (or an optical system provided with a succession of lenses) interposed between the object and a means for observing the image created by the lens or the optical system in the image plane of this lens or this system.
- the object emits light rays that pass through the lens or the succession of lenses and form an image observed by the observation means.
- the observed object is a light source which, by definition, the intensity of the rays emitted can be increased
- the intensity of the rays emitted can be increased
- the object itself and the instrument that observes it may constitute a source of parasitic light when some of the rays emitted by the object undergo internal reflection. on the convex back surface of the lens.
- any disturbance of the light rays emitted naturally by the object is to be prohibited, especially and especially those induced by the optical system that observes it, and especially and especially those that would absorb a portion of the intensity of the flow emitted by the object.
- a cap of absorbent material is contiguous on the rear surface of the lens (that directed towards the observation means and which is convex), the front surface of the cap (directed towards the object) being thus concave ( in addition, in the illustrated example, the rear surface of the cap is convex).
- This goal is achieved by placing an absorbing optical element between the imaging system (source) and the subject according to an object (source) / second element (Absorbent) / First Element (Disruptor) / Observer.
- the second surface (Convexity) of the absorbent cap this time is oriented towards the object (light source). in the present case of observation of an object, in particular for metrology applications, the object is not to disturb the object observed due to the return of stray light through the observation system.
- This goal is achieved by an absorbing optical element that is placed between the object and the rest of the observation system in the sequence Object / First Element (Disturbant) / Second Element (Absorbent) / Observer.
- the second surface (convexity) of the absorbent cap is thus oriented towards the observer or the subject.
- optical coupling is to be understood as the fact that a major part of the light rays passing through the rear surface of the lens, also crosses the front surface of the cap of absorbent material.
- absorbent material is to be understood as a light-absorbing material emitted by the object, with a non-uniformly zero absorption rate in the visible range (considered between 400 and 800 nm).
- the absorbent material may be a filter or a glass with an absorption coefficient between 20 and 40% so as to strongly attenuate the rays while maintaining an acceptable intensity for the transmitted rays.
- the material used can be a spectrally neutral absorbing glass (Schott [R15] series NG lenses or ND series the manufacturer Hoya).
- an ND25 or NG5 material may be used.
- optical adhesive film NOA65 for example
- suitable index and optically negligible thickness We choose in Generally speaking, an index close to that of one of the glasses, the indices often being close to 1.5 to 1.6 for example.
- the thickness will be from a few microns to ten microns.
- the physical thickness of the shell must be greater than the coherence length of the light emitted or reflected by the observed object 9 in order to overcome the appearance of interference phenomena. Practically, this minimum physical thickness will be for "natural light" type radiation of between 0.1 and 2 mm.
- Figure 7 describes the component obtained. Such a component will be used in a microscopic or conoscopic objective type optical system in place of the "conventional" convergent element.
- the absorbing material of the shell is crossed only once if this ray is transmitted (ray 19) while it will be crossed 4 times if this ray is retro-reflected ( radius 20) inside the component.
- the retro-reflected rays by the component are therefore 4 times more absorbed than the transmitted rays.
- the function of the shell is to decrease the intensity of the rays reflected on the object and to do so thanks to the absorbing nature of its constituent material.
- the thickness traversed by the critical angle CC is given by:
- the choice of the refractive index of the shell can also be used to reduce internal reflections, because it can be chosen so as to increase the critical angle obtained at the interface between the lens and the shell, and that obtained at the back of the shell at its interface with the air, and thus increase the angular aperture of incident rays not likely to be reflected.
- n2 index of the shell can result from a compromise between different phenomena:
- FIG. 12 which represents the evolution of the critical angle obtained at the interface between the shell and the air (at the rear surface 6 of the shell 2) is all the weaker than the refractive index n2 for the shell is high, which results in a high refractive index for the shell could increase the risk of internal reflection that we want to avoid.
- a critical angle is obtained at the interface between the lens and the shell, of 42 ° (well above the critical angle obtained for the lens in interface with the air) and a critical angle at the interface between the rear of the shell and the air, of 56 ° which increases the angular difference of the rays which will not be reflected.
- it can be set to a value between nl-30% and nl + 30%.
- the shell being optically coupled to the lens with an optical adhesive film (NOA65 for example) of index 1, 524 and of thickness ⁇
- the flux originating from the retro-reflected rays goes from 2.4W / cm 2 to 10mW / cm 2 , a decrease of a factor 240 when all the radii are taken into account.
- a simple optical objective can be obtained by combining the optical device according to the invention 7 with an optical system 10 composed of one or more lenses 14 of which at least one or both may be provided with their rear surface opposite to the observed object 8, a shell of absorbent material, for creating on the image plane 11 of the system, an image that can be observed visually through an eyepiece 16 or automatically through a matrix sensor (not shown in this figure) of the objective or an optical instrument comprising this lens, located at the rear of the lens / cap pair.
- a microscopic type objective is used to produce, in the image plane 11 of said objective, an enlarged image 21 of the object 8, image which is observed visually by means of an eyepiece 16 or automatically by means of a matrix sensor (not shown in this figure) associated with an optical transport and magnification system 10, 15.
- the optical element according to the invention 7 provided with a lens optically coupled to a shell will be associated with an optical system 10, composed of one or more lenses 14 making it possible to obtain the desired focal length and to correct, in a manner known to those skilled in the art, the various geometric and colorimetric aberrations of the system, and supplemented by a field lens 15, also called a tube lens.
- one or more of the lenses 14 of the optical system 10 are of the convergent type and also have internal total reflections, they may advantageously be replaced by optical elements of the type of the invention and thus be provided with a reduction shell of the internal reflection.
- a lens of the conoscopic type is used to produce, in the image plane of said lens, an image 21 of the angular distribution of the flux emitted or reflected by the object, which image is observed visually thanks to an eyepiece 16, or automatically thanks to a matrix sensor 17 associated where appropriate with a magnifying optical system 18 and a field lens 15.
- a plurality of unitary sensors placed in the image plane 11 can be used to observe the image 21.
- the entrance pupil of the transport objective 18 acts as an opening diaphragm and adjusts the size of the spot analyzed
- each sensor will be preceded by an opening aperture diaphragm
- the optical element 7 will be associated in known manner with an optical system 10 composed of one or more lenses 14 to obtain the desired focal length and to correct the various geometric and colorimetric aberrations of the system.
- one or more of the lenses 14 are of convergent type and also have internal total reflections, they may advantageously be replaced by optical elements of the type of the invention.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Lenses (AREA)
- Microscoopes, Condenser (AREA)
- Optical Elements Other Than Lenses (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2016571318A JP6728560B2 (ja) | 2014-06-02 | 2015-06-01 | 物体を観察するためのレンズユニット、光学機器及び光学デバイス |
DE112015002598.7T DE112015002598T5 (de) | 2014-06-02 | 2015-06-01 | Optische vorrichtung zum beobachten eines objekts und minimieren des internen reflexionphänomens |
US15/315,532 US10732381B2 (en) | 2014-06-02 | 2015-06-01 | Optical device for observing an object, minimising the internal reflection phenomenon |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1454975 | 2014-06-02 | ||
FR1454975A FR3021759B1 (fr) | 2014-06-02 | 2014-06-02 | Dispositif optique pour l'observation d'un objet, minimisant le phenomene de reflexion interne |
Publications (2)
Publication Number | Publication Date |
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WO2015185837A1 true WO2015185837A1 (fr) | 2015-12-10 |
WO2015185837A9 WO2015185837A9 (fr) | 2016-01-14 |
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PCT/FR2015/051433 WO2015185837A1 (fr) | 2014-06-02 | 2015-06-01 | Dispositif optique pour l'observation d'un objet, minimisant le phenomene de reflexion interne |
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Country | Link |
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US (1) | US10732381B2 (fr) |
JP (1) | JP6728560B2 (fr) |
DE (1) | DE112015002598T5 (fr) |
FR (1) | FR3021759B1 (fr) |
WO (1) | WO2015185837A1 (fr) |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
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JPH08179105A (ja) * | 1994-12-22 | 1996-07-12 | Ricoh Co Ltd | レンズ系およびそのフレア防止方法 |
JPH09279109A (ja) * | 1996-04-16 | 1997-10-28 | Asahi Optical Co Ltd | 光学部品用接着剤 |
US5880887A (en) | 1996-08-16 | 1999-03-09 | Dai Nippon Printing Co., Ltd. | Lenticular lens sheet, display front plate and transmission type projection screen |
US20100110569A1 (en) * | 2008-10-30 | 2010-05-06 | Hon Hai Precision Industry Co., Ltd. | Lens system |
JP2011164494A (ja) * | 2010-02-12 | 2011-08-25 | Canon Inc | 光学素子用の遮光膜、遮光塗料および光学素子 |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
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JPS5370454A (en) * | 1976-12-06 | 1978-06-22 | Nippon Chemical Ind | Conoscope image observation opticals |
JPH06337304A (ja) * | 1993-05-31 | 1994-12-06 | Fuji Photo Optical Co Ltd | Ndフイルタ |
US5980453A (en) * | 1996-02-22 | 1999-11-09 | Precision Optics Corporation | Endoscope with low distortion |
KR100553887B1 (ko) * | 2003-06-24 | 2006-02-24 | 삼성전자주식회사 | 수직 및 수평으로 광시야각을 갖는 영상표시용 스크린 및이를 구비하는 프로젝션 텔레비전 |
JP4114656B2 (ja) * | 2004-10-20 | 2008-07-09 | セイコーエプソン株式会社 | レンズ基板、レンズ基板の製造方法、透過型スクリーンおよびリア型プロジェクタ |
US8014081B2 (en) * | 2005-02-09 | 2011-09-06 | Tamron Co., Ltd. | Chromatic aberration compensating image optics |
WO2012039709A1 (fr) * | 2010-09-22 | 2012-03-29 | Dow Corning Corporation | Article électronique et son procédé de formation |
JP5944174B2 (ja) * | 2012-02-03 | 2016-07-05 | スカラ株式会社 | 顕微鏡とカメラの接続具 |
JP5836833B2 (ja) * | 2012-02-20 | 2015-12-24 | キヤノン株式会社 | 光学素子用の遮光塗料、遮光膜および光学素子 |
-
2014
- 2014-06-02 FR FR1454975A patent/FR3021759B1/fr active Active
-
2015
- 2015-06-01 DE DE112015002598.7T patent/DE112015002598T5/de active Pending
- 2015-06-01 WO PCT/FR2015/051433 patent/WO2015185837A1/fr active Application Filing
- 2015-06-01 JP JP2016571318A patent/JP6728560B2/ja active Active
- 2015-06-01 US US15/315,532 patent/US10732381B2/en active Active
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH08179105A (ja) * | 1994-12-22 | 1996-07-12 | Ricoh Co Ltd | レンズ系およびそのフレア防止方法 |
JPH09279109A (ja) * | 1996-04-16 | 1997-10-28 | Asahi Optical Co Ltd | 光学部品用接着剤 |
US5880887A (en) | 1996-08-16 | 1999-03-09 | Dai Nippon Printing Co., Ltd. | Lenticular lens sheet, display front plate and transmission type projection screen |
US20100110569A1 (en) * | 2008-10-30 | 2010-05-06 | Hon Hai Precision Industry Co., Ltd. | Lens system |
JP2011164494A (ja) * | 2010-02-12 | 2011-08-25 | Canon Inc | 光学素子用の遮光膜、遮光塗料および光学素子 |
Also Published As
Publication number | Publication date |
---|---|
US20170176715A1 (en) | 2017-06-22 |
FR3021759A1 (fr) | 2015-12-04 |
FR3021759B1 (fr) | 2018-02-09 |
WO2015185837A9 (fr) | 2016-01-14 |
DE112015002598T5 (de) | 2017-07-20 |
JP6728560B2 (ja) | 2020-07-22 |
JP2017519245A (ja) | 2017-07-13 |
US10732381B2 (en) | 2020-08-04 |
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