CN1257495C - Holographic optical storage device and its storage information fetch method - Google Patents

Abstract

The present invention relates to a holographic optical storage device and a reading method of storage information. When information on a storage material is read, a reading reference light incidence angle and a reading signal light emergence angle are calculated accurately, and the incidence direction of reference light and a light detector are adjusted to make the light detector obtain accurate information when the signal light emergence angle direction is read.

Description

The read method of holographic optics storage device and store information thereof

Technical field

The present invention relates to optical disc drive, and be particularly related to the read method of holographic optics storage device and store information thereof.

Background technology

Please refer to Fig. 1, its illustrate is known holographic optical disc drive synoptic diagram.In general, the holographic optics storage device is made up of flashlight, information plane, reference light, storage medium and photodetector.

Wherein, utilize a light source, for example laser is divided into two road light beams through optical splitter (not illustrating).Wherein one light beam irradiates be in an information plane 10, for example microreflection lens array or liquid crystal panel, after promptly become a flashlight 15.And another road light beam is reference light 20.When flashlight 15 and reference light 20 shine simultaneously in storage medium 30, photopolymer (photopolymer) for example, flashlight 15 can produce interference fringes 35 with reference light 20, and interference fringe promptly is formed among the storage medium 30.Afterwards, when storage medium 30 during only by reference light 20 irradiation, can output one information light 40 at the bearing of trend of original signal light 15 (that is, the emergence angle of flashlight).And on the direction that information light 40 advances, place photodetector 50, promptly can obtain the information on the prime information plane 10.

That is to say, when writing storage medium 30, simultaneously flashlight 15 and the formed interference fringe 35 of reference light 20 irradiations are recorded in the storage medium 30, promptly finish writing of information.When reading information, utilize reference light 20 to shine interference fringe 35 in storage medium 30, can be at the bearing of trend output information light 40 of original signal light 15, and utilize photodetector 50 can obtain to be stored in information in the storage medium.

Please refer to Fig. 2 (a), 2 (b), its illustrate is the relation between storage medium internal signal light, reference light and interference fringe.In Fig. 2 (a), K _sBe signal direction of light, K _rBe the reference direction of light, K then is the formed grating of interference fringe (Grating) direction.And the relation between these three directions is shown in Fig. 2 (b), that is, K _r+ K=K _sTherefore, under ideal state, the vertical mutually information that can obtain to be stored in the storage medium of bearing of trend of photodetector 50 and information light when reading information.

Because (for example: photopolymer) write fashionable meeting in information and produce deformation, in addition, storage medium also can produce deformation to storage medium when temperature change.And the above situation all can cause the grating that is stored in the storage medium to change its direction and value.So during information on reading storage medium, photodetector may detect less than information light, perhaps detect wrong information.

Summary of the invention

The read method that the purpose of this invention is to provide a kind of holographic optics storage device and store information thereof, the position of reference light incident angle and photodetector was in order to obtain correct information when accurately calculating was read.

The present invention proposes the read method of store information in a kind of holographic optics storage device, comprises the following steps: when writing information to storage medium length, flashlight incident angle and the reference light incident angle of record storage medium all directions; During information in reading storage medium, measure the deformation quantity of storage medium all directions; Utilize the deformation quantity of length, flashlight incident angle, reference light incident angle and storage medium all directions of the storage medium all directions of record, calculate when reading the reference light incident angle and flashlight emergence angle when reading; And reference light incident angle transmitted-reference light is to storage medium when reading, and flashlight emergence angle direction is inserted photodetector when reading.

The present invention proposes a kind of holographic optics storage device, comprising: storage medium, and flashlight can first incident angle shine in storage medium, and reference light can second incident angle shine in storage medium; The deformation detecting unit can detect the deformation quantity of storage medium all directions; Computing unit according to the deformation quantity of length, first incident angle, second incident angle and the storage medium all directions of storage medium all directions, calculates when reading the reference light incident angle and flashlight emergence angle when reading; And photodetector places the direction of flashlight emergence angle when reading.

The present invention proposes a kind of holographic optics storage device, comprising: but the storage medium of recording interference fringe, and wherein interference fringe is formed with first incident angle and second incident angle irradiation storage medium respectively by first incident light and second incident light; The deformation detecting unit can detect the deformation quantity of storage medium all directions; Computing unit according to the deformation quantity of length, first incident angle, second incident angle and the storage medium all directions of these storage medium all directions, calculates when reading the reference light incident angle and flashlight emergence angle when reading; Reference light reference light incident angle when reading is shone in store information; And photodetector places the direction of flashlight emergence angle when reading.

Description of drawings

Fig. 1 illustrate is known holographic optical disc drive synoptic diagram;

Fig. 2 (a), 2 (b) are the relation between storage medium internal signal light, reference light and interference fringe;

Fig. 3 illustrate is the relation between flashlight, reference light and the interference fringe after the storage medium distortion;

Fig. 4 illustrate is flashlight, the relation of reference light between the storage medium interface;

Fig. 5 illustrate is the read method of store information in the holographic optics storage device of the present invention; And

Fig. 6 illustrate is holographic optics storage device synoptic diagram of the present invention.

Embodiment

Please refer to Fig. 3, its illustrate is the relation between flashlight, reference light and the interference fringe after the storage medium distortion.Compare with Fig. 2 (b), when storage medium was out of shape, the grating that is stored in the storage medium can change its direction and value, and therefore, the direction of change and value are with K ' expression.If do not change with reference to direction of light and shine in storage medium the information light K that is exported this moment _s' with information light K _sThe direction difference, so during information on reading storage medium, photodetector may detect less than information light, perhaps detect wrong information.

Please refer to Fig. 4, its illustrate is flashlight, the relation of reference light between the storage medium interface.Wherein, plane of incidence is the formed plane of XY axle, Ω _1extBe the aerial incident angle of flashlight, Ω _2extBe the aerial incident angle of reference light, K _sFor its refraction angle of the direction of flashlight in storage medium is Ω _1in, K _rFor its refraction angle of the direction of reference light in storage medium is Ω _2in, K is the direction of grating after flashlight and the interference fringe that reference light produces.

Wherein, n is the refractive index of storage medium, K _r+ K=K _s, and | K _s|=| K _r|=2 π/λ, | K|=2 π/τ, λ be flashlight with reference to light wavelength, τ is the space periodic of grating.

Therefore, utilize vectorial addition and Snell ' s Law to derive

$K_z=K_{\mathrm{sz}}-K_{\mathrm{rz}}=\frac{2\mathrm{\π}}{\mathrm{\λ}}(\sqrt{n^2-{\sin }^2{\mathrm{\Ω}}_{1\mathrm{ext}}}-\sqrt{n^2-{\sin }^2{\mathrm{\Ω}}_{2\mathrm{ext}}})---\left(1\right)$

$K_x=K_{\mathrm{sx}}-K_{\mathrm{rx}}=\frac{2\mathrm{\π}}{\mathrm{\λ}}({\sin \mathrm{\Ω}}_{1\mathrm{ext}}+{\sin \mathrm{\Ω}}_{2\mathrm{ext}})---\left(2\right)$

By (1), (2) as can be known, can learn K by the incident angle of reference light and flashlight _z(the grating vector is at the component of Z axle) and K _x(the grating vector is at the component of X-axis).Certainly, if K _zWith K _xKnown, also can draw the incident angle of reference light and flashlight.

In addition, by K=2 π/τ as can be known, Δ K/K=-Δ τ/τ ... ... (3)

By (3) as can be known, Δ K _i/ K _i=-Δ τ i/ τ i, i can be X, Y, Z.That is, known τ _zWith K _zSize, as long as measure Δ τ _zChange can learn Δ K _zIn like manner, known τ _xWith K _xSize, as long as measure Δ τ _xChange can learn Δ K _x

Because the grating vector magnitude of the grating vector of information when writing storage medium when reading information is also inequality with direction.Therefore, when information light writes store information, must write down the incident angle of length, reference light and the flashlight of storage medium all directions, in order to learn grating vector K (component that comprises all directions), with the space periodic τ (component that comprises all directions) of grating.

When reading the information of storage medium, must measure the deformation quantity on the storage medium all directions once more, and obtain the variation delta τ of the grating space periodic of all directions _i, i can be X, Y, Z.Therefore, utilize (3) formula, can learn the change amount Δ K (component that comprises all directions) of grating.

Because the vector of the grating after distortion K '=K+ Δ K.Therefore, can try to achieve the grating vector of all directions after the deformation:

K _z′＝K _z+ΔK _z?......(4)

K _x′＝K _x+ΔK _x?......(5)

And substitution as a result (1), (2) formula of (4), (5) can be obtained the incident angle Ω that another organizes reference light and flashlight _1ext' with Ω _2ext'.

The reference light that obtains and the incident angle Ω of flashlight _1ext' with Ω _2ext' representative is when reading the information of storage medium, and reference light must be with Ω _1ext' angle be incident to storage medium, and at Ω _2ext' working direction insert photodetector and can obtain correct information.

Please refer to Fig. 5, its illustrate is the read method of store information in the holographic optics storage device of the present invention.

Step S1: when writing information to storage medium, length, flashlight incident angle, the reference light incident angle of record storage medium all directions;

Step S2: during information in reading storage medium, measure the deformation quantity of storage medium all directions;

Step S3: utilize the deformation quantity of length, flashlight incident angle, reference light incident angle and the storage medium all directions of precedence record storage medium all directions, calculate when reading the reference light incident angle and flashlight emergence angle when reading;

Step S4: adjust reference light reference light incident angle when reading and expose to storage medium, and the direction of flashlight emergence angle is inserted photodetector when reading.

Please refer to Fig. 6, its illustrate is optical disc drive synoptic diagram of the present invention.Formed by flashlight 115, information plane 110, reference light 120, storage medium 130, deformation detecting unit 160, computing unit 170 and photodetector 150 in the holographic optics storage device of the present invention.

Wherein, the deformation quantity of storage medium 130 all directions between deformation detecting unit 160 can detection information writes and reads, computing unit 170 then utilizes the deformation quantity of length, flashlight 115 incident angles, reference light 120 incident angles and storage medium 130 all directions of record storage medium 130 all directions, calculates when reading the reference light incident angle and flashlight emergence angle when reading.Therefore, the reference light incident angle provides reference light 120 to shine in storage medium 130 when reading when reading information, and the direction of information light emergence angle can be inserted photodetector 150 and comes reception information when reading.

Therefore, advantage of the present invention is the read method that proposes a kind of holographic optics storage device and store information.During information on reading storage medium, accurately calculate when reading the reference light incident angle and flashlight emergence angle when reading, and the incident direction of adjusting reference light makes photodetector reading the correct information of acquisition on the working direction of flashlight.

In sum, though the present invention with preferred embodiment openly as above, it is not in order to limit the present invention.Those skilled in the art can be used for a variety of modifications and variations without departing from the spirit and scope of the present invention, so protection scope of the present invention is as the criterion with appended claim.

Claims (14)

1. the read method of store information in the holographic optics storage device comprises the following steps:

When writing information to one storage medium, write down length, a flashlight incident angle and a reference light incident angle of a plurality of directions of this storage medium;

During this information in reading this storage medium, measure the deformation quantity of a plurality of directions of this storage medium;

Utilize the deformation quantity of length, this flashlight incident angle, this reference light incident angle and these these directions of storage medium of these these directions of storage medium of record, flashlight emergence angle when calculating a reference light incident angle and when reading and reading; And

Reference light incident angle is launched a reference light to this storage medium when reading with this, and the direction of flashlight emergence angle is inserted a photodetector when reading with this.

2. the read method of store information in the holographic optics storage device as claimed in claim 1, wherein this storage medium is formed by a photopolymer.

3. the read method of store information in the holographic optics storage device as claimed in claim 1 wherein utilizes a light source to form two light beams through an optical splitter, and one first light beam in this two light beam is this reference light.

4. the read method of store information in the holographic optics storage device as claimed in claim 3, wherein this light source is a laser.

5. the read method of store information in the holographic optics storage device as claimed in claim 3, wherein one second light beam in this two light beam promptly forms this flashlight after by an information plane.

6. the read method of store information in the holographic optics storage device as claimed in claim 5, wherein this information plane is a liquid crystal panel.

7. the read method of store information in the holographic optics storage device as claimed in claim 5, wherein this information plane is a microreflection lens array.

8. holographic optics storage device comprises:

One storage medium;

One flashlight, this flashlight can one first incident angle shine in this storage medium;

One reference light, this reference light can one second incident angle shine in this storage medium;

One deformation detecting unit, this deformation detecting unit can detect the deformation quantity of these storage medium all directions;

One computing unit, this computing unit be according to the deformation quantity of length, this first incident angle, this second incident angle and these storage medium all directions of these storage medium all directions, flashlight emergence angle when calculating a reference light incident angle and when reading and reading; And

One photodetector, the direction of flashlight emergence angle when placing this to read.

9. holographic optics storage device as claimed in claim 8, wherein this storage medium is formed by a photopolymer.

10. holographic optics storage device as claimed in claim 8 wherein utilizes a light source to form two light beams through an optical splitter, and one first light beam in this two light beam is this reference light.

11. holographic optics storage device as claimed in claim 10, wherein this light source is a laser.

12. holographic optics storage device as claimed in claim 10, wherein one second light beam in this two light beam promptly forms this flashlight after by an information plane.

13. holographic optics storage device as claimed in claim 12, wherein this information plane is a liquid crystal panel.

14. holographic optics storage device as claimed in claim 12, wherein this information plane is a microreflection lens array.

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