CN100575991C - Polarization diffraction device and optic probe device - Google Patents

Abstract

Being implemented in wavelength X 1 works as polarization diffraction device, in wavelength X 2 no matter the incident polarization state as why not working, have as diffraction grating high-transmission rate wavelength selectivity polarization diffraction device and use the optic probe device of described polarization diffraction device.Polarization diffraction device to have respectively the 1st circularly polarized light with the different incident light of at least two bundle wavelength of the 2nd circularly polarized light of the 1st circularly polarized light opposite spin, according to incident light wavelength and polarization state selectively with its diffraction or it is passed through.And do not comprise two incident light wavelengths in the reflection of incident light wave band to the 1st circularly polarized light at least.

Description

Polarization diffraction device and optic probe device

Technical field

The optical-head apparatus that the present invention relates to polarization diffraction device and polarization diffraction device is comprised as inscape particularly relates to use and has polarization diffraction device and the optic probe device that the optical activity material of the big rotatory dispersion characteristic that causes is reflected in the circular polarization selection.

Background technology

The nematic crystal that comprises cholesterol phase liquid crystal and chirality (カ イ ラ Le) material is the cholesterol liquid crystal mutually that forms the twist alignment of helical structure, known have a following performance, promptly under the suitable situation of the wavelength X of pitch P and incident light, be reflected from the circularly polarized light of having of the hand of spiral incident sense of rotation identical, have the circularly polarized light correlativity (this is called as " the selection reflection of circularly polarized light ") that circularly polarized light that opposite spin is arranged sees through with the torsional direction of liquid crystal.

Again, in this cholesteric phase liquid crystal, suppose that for example the torsional direction of liquid crystal is the right-hand rotation direction, then for dextrorotary circularly polarized incident light, there is the wave band (this is called as " reflected waveband ") that brings circular polarization to select reflection, near this reflected waveband, demonstrate big rotatory dispersion (optically-active is because of the different phenomenon of wavelength).On the other hand, for the circularly polarized incident light to anticlockwise, do not have reflected waveband, therefore demonstrate smaller rotatory dispersion, this situation is on the books in non-patent literature 1.

That is to say that at the reflected waveband transmission wave band nearby of the circular polarization selection reflection function with cholesterol phase liquid crystal, dextrorotary circularly polarized light with in the circularly polarized light of anticlockwise significantly different situation of optical activity takes place.

Again, in the smaller cholesterol phase liquid crystal of pitch P, known with the cholesterol medium temperature area discover cholesterol indigo plant of isotropic phase (コ レ ス テ リ Star Network Block Le one) phase (liquid crystal of the blue phase state of this cholesterol is called " blue phase liquid crystal ") mutually.

This blue phase liquid crystal forms has the three-dimensional periodic crystalline network that the dual cylindric part of reversing the spiral inner structure is spatially arranged regularly, makes the wavelength that satisfies diffraction conditions and the incident light generation Bragg diffraction of incident angle.Here the Bragg diffraction light of Fa Shenging is the same with cholesterol phase liquid crystal relevant with circular polarization, but with cholesterol liquid crystal phase ratio mutually, circular polarization selects the reflected waveband of reflection narrow, so near the transmission wave band narrower reflected waveband, right-handed polarized light has significantly different with left-hand polarization light optical activity.

Again, the temperature range of existing blue phase is about several ℃ an extremely narrow scope, and the utilitarian element of therefore using blue phase is difficult to realize.But such report (reference example non-patent literature 2) is arranged in recent years, i.e. mix monomer in liquid crystal, temperature province irradiation ultraviolet radiation at blue phase liquid crystal makes the monomer producing high-molecular with this, and the temperature range that obtains blue phase liquid crystal expands the polymer-stabilized blue phase liquid crystal more than 60 ℃ to.

But, on the information recording surface of optical recording medias such as such CD such as CD and DVD and photomagneto disk, carry out in the optic probe device of information record and/or information playback (hereinafter referred to as " record reproducing "), the emergent light that penetrates from semiconductor laser is concentrated on the information recording surface of CD by object lens, the formation back light that is reflected simultaneously, this back light is imported into photo detector as photodetector by beam splitter.Here, this beam splitter for example adopts as a kind of holographic beam separation vessel of diffraction element etc., can utilize diffraction to make the direct of travel deflection of light beam like this, guides it into photodetector, has therefore realized the miniaturization of optical head.

Again, in the optic probe device that the semiconductor laser that semiconductor laser that DVD uses and CD use is installed, the DVD/CD that the information of the CD that can use specification different DVD and CD as optical recording media is carried out recording playback exchanges optic probe device and also obtains practicability.

Patent documentation 1 has been put down in writing polarization diffraction device as described below, promptly for the miniaturization that realizes such optic probe device and high light utilization ratio, the unusual light that is processed as the wavelength that the phase differential of the jog of the rectangle diffraction grating that the high molecule liquid crystal that makes the direction of orientation unanimity constitutes uses for CD is the natural several times of wavelength, and be 0 for normal light, thereby can see through the normal polarized light of the 650nm wave band that DVD uses, and diffraction abnormal polarization light, the incident light that can make simultaneously the 790nm wave band that CD uses sees through and no matter its polarization state how, possesses the polarization diffraction device of wavelength selectivity.

" physics of liquid crystals " of non-patent literature 1:Chandrasekhar work, Ji Gang bookstore publishes nineteen ninety-five, p.260～261 (the 4th chapter, Fig. 4 .1,6) (Chandrasekhar, " Liquid Crystals ", Secondedition, Cambridge University Press Chap.4 Fig.4.1,6)

Non-patent literature 2: " Nature Materials (nature material) ", Vol.1, no.1, MacmillanPress, 2002, Sep., p.64～68

Patent documentation 1: TOHKEMY 2001-174614 communique

Summary of the invention

But, in such polarization diffraction device, if the grating space of polarization diffraction device is narrow, because the influence of grating wall just has the low problem of abnormal polarization light transmission of 790nm wave band.

The present invention In view of the foregoing makes, its purpose is, provide light to work as polarization diffraction device for wavelength X 1, for the light of the wavelength X 2 that is different from wavelength X 1, irrespectively do not work with the incident polarization state and have the polarization diffraction device of wavelength selectivity of high-transmission rate and the optic probe device that uses this element as diffraction element.

According to the 1st aspect of the present invention, a kind of polarization diffraction device is provided, it makes the light generation diffraction of specific wavelength, wherein,

Described polarization diffraction device utilizes optical activity material and these two kinds of being connected to form diffraction grating of optical material of optical isotropy material and forms,

By using described optical activity material to become with a kind of materials processing in the described optical isotropy material after section configuration has the concavo-convex grating of periodicity, at least at the described optical activity material of recess filling of the described grating of this processing and the another kind of material in the described optical isotropy material and form described diffraction grating

Wherein this optical activity material has reflected waveband at the 1st circularly polarized light with a sense of rotation, and at a kind of circularly polarized light generation diffraction in the 1st circularly polarized light of the outer specific wavelength of this reflected waveband and sense of rotation the 2nd circularly polarized light opposite with the 1st circularly polarized light, and, it diffraction takes place is seen through at another circularly polarized light in described the 1st circularly polarized light and described the 2nd circularly polarized light.

According to the 2nd aspect of the present invention, a kind of polarization diffraction device is provided, its for have respectively the 1st circularly polarized light and with the 1st wavelength X 1 of the 2nd circularly polarized light of the 1st circularly polarized light reverse direction rotation and the incident light that is not equal to the 2nd wavelength X 2 of λ 1, according to described two incident light wavelengths and polarization state diffraction or transmission selectively, it is characterized in that

Described polarization diffraction device utilizes optical activity material and these two kinds of being connected to form diffraction grating of optical material of optical isotropy material and forms,

By using described optical activity material to become with a kind of materials processing in the described optical isotropy material after section configuration has the concavo-convex grating of periodicity, at least at the described optical activity material of recess filling of the described grating of this processing and the another kind of material in the described optical isotropy material and form described diffraction grating

Described polarization diffraction device has the reflected waveband that reflection is selected in the circular polarization of bringing, and this reflected waveband at the incident light of described the 1st circularly polarized light, is not contained in described the 1st wavelength X 1 and described the 2nd wavelength X 2 in the object of reflection wavelength at least.

The polarization diffraction device of the present invention the 3rd aspect, be in the polarization diffraction device aspect the 2nd, have in the described incident light of described the 1st wavelength X 1 and described the 2nd wavelength X 2, described incident light as described the 1st wavelength X 1 of described reflected waveband transmission peak wavelength nearby, compare with described the 2nd wavelength X 2, with the optical activity material of the rotatory dispersion function with more relatively discovery, the 1st circularly polarized incident light that makes described the 1st wavelength X 1 wavelength polarization of diffraction is selectively selected the diffraction function.

The polarization diffraction device of the present invention the 4th aspect, be in the polarization diffraction device aspect the 2nd, in the incident light of two described different wave lengths, a wavelength is in the shortwave side shorter than described reflected waveband, a wavelength is in the long wave side than described reflection wave segment length, employing makes the 1st circularly polarized light and the 2nd circularly polarized light diffraction or the transmission of the incident light of a wavelength selectively in shortwave side and the optical activity material that the long wave side than described reflection wave segment length has different rotatory dispersion functions shorter than described reflected waveband.

The polarization diffraction device of the present invention the 5th aspect is in the polarization diffraction device aspect the 2nd, has:

Use described optical activity material to become section configuration to have the grating of periodically concavo-convex raster shape with a kind of materials processing in the optical isotropy material, described optical activity material wavelength X the refractive index of described the 1st circularly polarized light and difference to the refractive index of described the 2nd circularly polarized light are designated as Δ n (λ) time, satisfy Δ n (λ 1)＞Δ n (λ 2), and Δ n (λ 2) ≈ 0, this optical isotropy material the refractive index of described the 2nd wavelength X 2 and described optical activity material about equally and

At least at the described optical activity material of recess filling of the described grating of this processing and the compaction material of the another kind of material in the described optical isotropy material.

The polarization diffraction device of the present invention the 6th aspect, be in the polarization diffraction device aspect the 5th, described optical activity material is made of cholesterol phase liquid crystal, the helical axis directions of described cholesterol phase liquid crystal is consistent with thickness direction, simultaneously to described the 1st circularly polarized light, described cholesterol phase liquid crystal has not described the 1st wavelength X 1 and described the 2nd wavelength X 2 is contained in described reflected waveband in the object of reflection wavelength, and the pitch that described cholesterol phase liquid crystal is had makes described the 1st wavelength X 1 for to compare the transmission peak wavelength of more close described reflected waveband relatively with described the 2nd wavelength X 2.

The polarization diffraction device of the present invention the 7th aspect, be in the polarization diffraction device aspect the 5th, described optical activity material is made of the polymer-stabilized cholesterol blue phase liquid crystal that utilizes macromolecule network to enlarge the temperature range of the blue phase of cholesterol, to described the 1st circularly polarized light, described polymer-stabilized cholesterol blue phase liquid crystal has not described the 1st wavelength X 1 and described the 2nd wavelength X 2 is contained in described reflected waveband in the object of reflection wavelength, and the wavelength selectivity that described polymer-stabilized cholesterol blue phase liquid crystal had simultaneously makes described the 1st wavelength X 1 for compare the transmission peak wavelength of relative more close described reflected waveband with described the 2nd wavelength X 2.

The polarization diffraction device of the present invention the 8th aspect is in the polarization diffraction device aspect the 4th, comprises

Suppose wavelength X be Δ n (λ) with respect to the refractive index of described the 1st circularly polarized light with respect to the difference of the refractive index of described the 2nd circularly polarized light the time,

For one wavelength in the different incident light of two wavelength,

The described optical activity material of Δ n (λ) ≈ 0 and

For at least one circularly polarized light of described the 1st circularly polarized light and described the 2nd circularly polarized light, the refractive index of refractive index and described optical activity material described optical isotropy material about equally.

The polarization diffraction device of the present invention the 9th aspect, be in the polarization diffraction device aspect the 8th, described optical activity material is made of cholesterol phase liquid crystal, the helical axis directions of described cholesterol phase liquid crystal is consistent with thickness direction, simultaneously to described the 1st circularly polarized light, whole wavelength that described cholesterol phase liquid crystal has not an incident light that two wavelength is different are contained in the described reflected waveband in the object of reflection wavelength, and the pitch that described cholesterol phase liquid crystal is had makes that reflected waveband is in the different incident light of described two wavelength, grow up than the shortest incident wave, reflected waveband than the ejected wave length of growing into most.

If the employing said structure then can be realized finding the polarization diffraction device that possesses wavelength selectivity of relevant characteristic with polarization that its diffraction efficiency is different for the 1st circularly polarized light and the 2nd circularly polarized light.

If the employing said structure then can be realized at least two incident lights that wavelength is different, find the polarization diffraction device that possesses wavelength selectivity with polarization for the 1st circularly polarized light characteristic of being correlated with different with its diffraction efficiency of the 2nd circularly polarized light.

If employing said structure, then can realize for the 1st circularly polarized light and the 2nd circularly polarized light, find the different characteristics relevant of its diffraction efficiency in the 1st wavelength X 1 with polarization, roughly the same in the 2nd wavelength X 2 its diffraction efficiencies, there is not to find the polarization diffraction device that possesses wavelength selectivity of the characteristic relevant with polarization.

If the employing said structure then can be realized in the different incident light of two wavelength at least, with the 1st circularly polarized light of the incident light of at least one wavelength and the 2nd circularly polarized light polarization diffraction device of diffraction or transmission selectively.

If employing said structure, then for the incident light of the 1st circularly polarized light and the 2nd circularly polarized light, find the different characteristics relevant with polarization of its diffraction efficiency in the 1st wavelength X 1,2 of the 2nd wavelength X regardless of the polarization of incident light state how, diffraction and going ahead does not see through.Therefore can realize that the light utilization ratio is high, possess the polarization diffraction device of wavelength selectivity.Particularly in the 2nd wavelength X 2, how therefore the refractive index of optical activity material and optical isotropy material can both obtain high-transmission rate regardless of grating space and raster shape about equally.

If the employing said structure, then owing to uses section configuration as the periodicity concaveconvex shape, the cholesterol phase liquid crystal of screw axis unanimity by adjusting the pitch of cholesterol phase liquid crystal, can be found circular polarization selection reflected waveband at wave band arbitrarily.Consequently, can access about the high polarization diffraction device of the design freedom of wavelength selectivity.

If the employing said structure, then because cholesterol phase high molecule liquid crystal is a solid, with cholesterol mutually low molecular weight liquid crystal compare, the molecular orientation stabilization can be implemented in the little polarization diffraction device of characteristic variations under the situation of environmental change such as temperature variation.And, can simplify production process owing to needn't be sealed in the unit.

If the employing said structure even then under the narrow and small situation in the wavelength interval of the 1st wavelength X 1 and the 2nd wavelength X 2, also can be realized the polarization diffraction device that wavelength selectivity is arranged that the light utilization ratio is high.

If employing said structure, incident light for the 1st wavelength X 1, the polarization beam splitter high as the light utilization ratio works, and for the incident light of the 2nd wavelength X 2, directly the advance light transmission component little as the light loss of the influence that is not subjected to incident polarized light works.Consequently, can realize using different wave length that CD is carried out the small-sized optic probe device that stable recording is reset.

If employing said structure, then at least one wavelength in the different incident light of at least two wavelength, irrespectively directly advance transmission with the polarization of incident light state and diffraction not, for the incident light of different wave length therewith, find to have for the 1st circularly polarized light different with the 2nd circularly polarized light diffraction efficiency with correlativity polarization.Therefore can realize the polarization diffraction device that wavelength selectivity is arranged that the light utilization ratio is high.

If employing said structure, then can realize selecting reflected waveband for the polarization of stipulating by the pitch of adjusting cholesterol phase liquid crystal, the big optical activity difference that utilization is found at short-wave band and length wave band, the polarization diffraction device that the light utilization ratio is high with wavelength selectivity.

If the employing said structure because cholesterol phase high molecule liquid crystal is solid, with cholesterol mutually low molecular weight liquid crystal compare, the molecular orientation stabilization can be implemented in the little polarization diffraction device of characteristic variations under the situation of environmental change such as temperature variation.And, can simplify production process owing to needn't be sealed in the unit.

According to a further aspect in the invention, provide a kind of optic probe device,

Possess

At least two semiconductor lasers of the light that emission at least two bundle wavelength are different,

The light that this semiconductor laser is launched be concentrated on object lens on the optical recording media,

With the beam splitter of the optical diffraction of at least one wavelength in the light of described optical recording media reflection and

Detect the photodetector of light of the described wavelength of described diffraction,

Carry out the record and/or the playback of described optical recording media,

Wherein, described beam splitter comprises each the described polarization diffraction device in the present invention the 3rd～9 aspect,

Described beam splitter is the hologram beam splitter that hologram pattern that the angle of the spacing of grating grid and grating grid distributes in grating formation face constitutes.

If the employing said structure then can be realized working as the high polarization beam splitter of light utilization ratio for a wavelength at least, at least one incident light, as working with the few light transmission component that directly advances of the irrelevant light loss of incident polarization.Consequently, can realize using different wave length that CD is carried out the small-sized optic probe device that stable recording is reset.

If the employing said structure then can form the high beam splitter of design freedom of small-sized and supplementary lens function etc., so can realize carrying out the small-sized optic probe device of record reproducing with high precision.

If employing the present invention, incident light for the 1st circularly polarized light and the 2nd circularly polarized light then can be provided, for the 1st wavelength X 1, find diffraction efficiency different with correlativity polarization, for the 2nd wavelength X 2, diffraction efficiency does not have to find with the correlativity of polarization, the polarization diffraction device with diffraction efficiency characteristic of wavelength polarization selectivity about equally.

Description of drawings

Fig. 1 is the sectional side view of structure example of the polarization diffraction device of expression the present invention the 1st example.

Fig. 2 represents that light injects the effect under the situation of polarization diffraction device shown in Figure 1, (A) is the 1st circularly polarized light of expression wavelength X 1, λ 2 key diagram that sees through state when injecting.(B) be the 2nd circularly polarized light of expression wavelength X 1, λ 2 key diagram that sees through state when injecting.

Fig. 3 is the sectional side view of structure example of the polarization diffraction device of expression the present invention the 2nd example.

Fig. 4 is the sectional side view of structure example of the polarization diffraction device of expression the present invention the 3rd example.

Fig. 5 is the sectional side view of structure example of the optic probe device of the expression polarization diffraction device of the present invention that uses the present invention's the 4th example.

Fig. 6 is the sectional side view of structure example of the polarization diffraction device of expression the present invention the 5th example.

Fig. 7 represents that light injects the effect under the situation of polarization diffraction device shown in Figure 6, (A) is the 1st circularly polarized light of expression wavelength X 1, λ 2, λ 3 key diagram that sees through state when injecting.(B) be the 2nd circularly polarized light of expression wavelength X 1, λ 2, λ 3 key diagram that sees through state when injecting.

Fig. 8 is the sectional side view of structure example of the polarization diffraction device of expression the present invention the 6th example.

Fig. 9 represents that light injects the effect under the situation of polarization diffraction device shown in Figure 8, (A) is the 1st circularly polarized light of expression wavelength X 1, λ 2, λ 3 key diagram that sees through state when injecting.(B) be the 2nd circularly polarized light of expression wavelength X 1, λ 2, λ 3 key diagram that sees through state when injecting.

Figure 10 is the sectional side view of structure example of the polarization diffraction device of expression the present invention the 7th example.

Figure 11 represents that light injects the effect under the situation of polarization diffraction device shown in Figure 10, (A) is the 1st circularly polarized light of expression wavelength X 1, λ 2, λ 3 key diagram that sees through state when injecting.(B) be the 2nd circularly polarized light of expression wavelength X 1, λ 2, λ 3 key diagram that sees through state when injecting.

Figure 12 represents that light injects the effect under the situation of polarization diffraction device shown in Figure 6, (A) is the 1st linearly polarized light that is parallel to paper of expression wavelength X 1, λ 2, λ 3 key diagram that sees through state when injecting.(B) be the 2nd linearly polarized light of expression wavelength X 1, λ 2, λ 3 key diagram that sees through state when injecting perpendicular to paper.

Figure 13 is the sectional side view of structure example of the optical head of the expression polarization diffraction device of the present invention that uses example 4 of the present invention.

Symbol description

12 wavelength semiconductor lasers

2 photodetectors

3 collimation lenses

4 object lens

53 wavelength semiconductor lasers

10,20,50,70,80,90 polarization diffraction devices

11 (34), 12,31 (42), 41 light-transmitting substrates

13,73,83,93 high molecule liquid crystal gratings

14,33,74,84,94 compaction materials

21 isotropy gratings

22 polymer-stabilized blue phase liquid crystals

23 cholesterol phase liquid crystal

30 wavelength selectivity diffraction elements

32 short wavelength's absorption gratings

40 phase elements

43 phase-plates

60,100 optic probe devices

The D CD

The R1 reflected waveband

The U assembly

λ 1 the 1st wavelength

λ 2 the 2nd wavelength

λ 3 the 3rd wavelength

Embodiment

Below with reference to figure best example of the present invention is elaborated.

The 1st example

Fig. 1 is the sectional view of the polarization diffraction device 10 of expression the present invention the 1st example.This polarization diffraction device 10 possesses light-transmitting substrate 11,12, at lattice that the high molecule liquid crystal that is provided with between this light-transmitting substrate 11,12 constitutes (below be referred to as " high molecule liquid crystal grating ") 13 and compaction material 14.

Wherein, light-transmitting substrate 11,12 is formed by the translucent materials such as glass with uniform refractive index.

Here, the high molecule liquid crystal layer of high molecule liquid crystal grating 13 is that the normal light refractive index that even coating for example contains chiral material is no, the cholesteryl liquid crystal monomer material of unusual optical index ne forms, by making it contain chiral material, can be formed in the cholesterol phase liquid crystal of the twist alignment of the one-tenth helical structure that screw axis is arranged on the thickness direction (Z direction) of liquid crystal layer.

On the other hand, compaction material 14 will be described in detail below, adopts the isotropy optical material with desired refractive index to constitute.

(1) at first, evenly coating contains for example normal light refractive index n o of chiral material on light-transmitting substrate 11, and the cholesteryl liquid crystal monomer material of unusual optical index ne forms.

By means of this, be formed on the cholesterol phase liquid crystal of the twist alignment of the one-tenth helical structure that screw axis is arranged on the thickness direction (Z direction) of liquid crystal layer corresponding to chiral material.If carry out ultraviolet ray irradiation etc. at this cholesterol phase mesomorphic state, make the monomer liquid crystal polymerizing curable, then form the fixing cholesterol phase high molecule liquid crystal of twist alignment.

Here, constitute the cholesterol phase high molecule liquid crystal of high molecule liquid crystal grating 13, has characteristic as described below, promptly from the incident light of its thickness direction (Z direction) vertical incidence, for the long-pending central wavelength lambda 0 of the mean refractive index n=(no+ne)/2 of pitch P that is equivalent to liquid crystal and liquid crystal layer, just

λ0＝P·(no+ne)/2

The light of wave band nearby (reflected waveband) makes the 1st circularly polarized light reflection with sense of rotation identical with the torsional direction of liquid crystal, makes the 2nd circularly polarized light transmission that has with the reverse rotation of the torsional direction of liquid crystal simultaneously.

Here, the reflected waveband R1 of the 1st circularly polarized light is equivalent to birefringence n=ne-no long-pending, just of pitch P and liquid crystal material

R1＝P·(ne-no)。

But, in the light of transmission peak wavelength λ 1 near this reflected waveband R1, for the 1st circularly polarized light big rotatory dispersion (because of the different phenomenon of wavelength difference optical activity) takes place only, but its degree is compared with above-mentioned wavelength X 1, and the incident light rotatory dispersion that departs from the wavelength X 2 of reflected waveband R1 reduces.

Here, the transmission peak wavelength λ 1 nearby of so-called reflected waveband R1 is so long as the optical activity material gets final product at the transmission peak wavelength that for example transparent wave band more than the wavelength 400nm has high-diffraction efficiency.That is to say,, suppose the thickness of optical activity material is designated as h, then Δ n (λ 1) h 〉=0.2 micron preferably in order to obtain high-diffraction efficiency.The thickness h of optical activity material, send out from processing easily, therefore h≤20 micron preferably, therefore, the transmission peak wavelength λ 1 that can be met the Δ n of Δ n (λ 1) 〉=0.01 is exactly a wavelength nearby, and the transmission peak wavelength λ that satisfies Δ n (λ 1)=0.01 is a critical wavelength.Again, the value of Δ n (λ 1) preferably satisfies 0.01≤Δ n (λ 1)≤0.2.This transmission peak wavelength λ 1 difference because of the optical activity material changes.

On the other hand, for the 2nd circularly polarized light that does not have reflected waveband, in the incident light of above-mentioned wavelength X 1 and wavelength X 2, form little rotatory dispersion.

For example in the incident light of wavelength X, if will be designated as n1 (λ), will be designated as n2 (λ) for the refractive index of the 2nd circularly polarized light for the refractive index of the 1st circularly polarized light of cholesterol phase high molecule liquid crystal, its poor (refringence) is designated as Δ n12 (λ), if promptly

Δn12(λ)＝|n1(λ)-n2(λ)|，

Then

I) the refractive indices n12 (λ 2) in wavelength X 2 for to approach 0 little numerical value, that is to say,

Δn12(λ2)＝|n1(λ2)-n2(λ2)|≈0 ……(1)

Ii) again, be bigger numerical value at the refractive indices n12 (λ 1) of wavelength X 1, that is to say,

Δn12(λ1)＝|n1(λ1)-n2(λ1)|＞Δn12(λ2) ……(2)

(2) then, to being formed on the light-transmitting substrate 11, the cholesterol phase high molecule liquid crystal that constitutes high molecule liquid crystal grating 13 is processed, and forming section is concavo-convex lattice shape, and concave depth is the lattice of d.For example in Fig. 1, express the example that protuberance is processed as the rectangular cross section shape, but in addition, for example also can adopt the sawtooth wave shape or make the sawtooth wave shape for being similar to the stair-stepping so-called seemingly blazed grating of intending.

Example as this raster shape job operation, also can utilize photoetching process forms pattern with photoresist on cholesterol phase high molecule liquid crystal layer after, utilize the reactive ion etching method that cholesterol phase high molecule liquid crystal is processed to form pattern, be processed into micron-sized fine raster shape with this.Also can adopt moulding, duplicating or ultraviolet ray to interfere job operations such as exposure with metal die again.

(3) then, carry out filling with transparent compaction material 14, the recess of the above-mentioned high molecule liquid crystal grating 13 of landfill clips light-transmitting substrate 12 from these compaction material 14 connections, simultaneously as polarization diffraction device 10 at least.This compaction material 14 is so long as the optical isotropy material, any material can, can shine the optics adhesives of polymerization, curing by means of ultraviolet ray but preferably adopt.

Also have, this compaction material 14 adopts in the incident light of wavelength X 1 and wavelength X 2, and to the cholesterol of the 2nd circularly polarized light refractive index compaction material that constitutes of the isotropy optical material of refractive index about equally of high molecule liquid crystal mutually.

By means of this, in the incident light of wavelength X 1 and λ 2, refringence for the 1st circularly polarized light high molecule liquid crystal grating 13 and compaction material 14, be equivalent to cholesterol phase high molecule liquid crystal, with respect to the above-mentioned refractive indices n12 (λ 1) and the Δ n12 (λ 2) of the 1st circularly polarized light and the 2nd circularly polarized light.

[1]. about the incident light of the 1st circularly polarized light

I) that is to say, for the high molecule liquid crystal grating 13 of the 1st circularly polarized light of wavelength X 1 and the refractive indices n1 (λ 1) of compaction material 14, be equivalent to for the above-mentioned refractive indices n12 (λ 1) of the 1st and the 2nd circularly polarized light of the wavelength X 1 of cholesterol phase high molecule liquid crystal, just

Δn1(λ1)＝Δn12(λ1)

＝|n1(λ1)-n2(λ1)|

＞Δ n12 (λ 2) (according to formula (2)) ... (3)

Ii) same, for the high molecule liquid crystal grating 13 of the 1st circularly polarized light of wavelength X 2 and the refractive indices n1 (λ 2) of compaction material 14, be equivalent to for the above-mentioned refractive indices n12 (λ 2) of the 1st and the 2nd circularly polarized light of cholesterol phase high molecule liquid crystal, just

Δn1(λ2)＝Δn12(λ2)

＝|n1(λ2)-n2(λ2)|

≈ 0 (according to formula (1)) ... (4)

Also have, Δ n1 (λ 2), if the numerical value below 20% of above-mentioned Δ n1 (λ 1), then in wavelength X 2, high molecule liquid crystal grating 13 be we can say about equally with the refractive index of compaction material 14.

[2]. about the incident light of the 2nd circularly polarized light

In the incident light of wavelength X 1 and wavelength X 2, do not take place for the high molecule liquid crystal grating 13 of the 2nd circularly polarized light and the refractive indices 2 (λ 1) and the Δ n2 (λ 2) of compaction material 14 again.That is to say,

Δn2(λ1)＝Δn2(λ2)≈0 ……(5)

Utilize Fig. 2 that the effect of the polarization diffraction device 10 of the 1st example is described below.

[1]. about the incident light of the 1st circularly polarized light

For the incident light of the 1st circularly polarized light,

I) for example for wavelength X 2, high molecule liquid crystal grating 13 is to approach 0 fractional value with the refractive indices n1 (λ 2) of compaction material 14 according to formula (4).Therefore shown in Fig. 2 (A), do not produce diffraction light and directly advance through polarization diffraction device 10.

Ii) again, for wavelength X 1, its refractive indices n1 (λ 1) is the finite value shown in the formula (3), therefore shown in Fig. 2 (A) diffraction light takes place.At this moment, for make for wavelength X 1 ± 1 diffraction efficiency is for maximum,

d＝λ1/(2·Δn1(λ1)) ……(6)

Wherein,

D: the recess depths of high molecule liquid crystal grating 13

Δ n1 (λ 1): the recess depths d of the high molecule liquid crystal grating 13 that cholesterol phase high molecule liquid crystal is constituted processes to such an extent that make to be met for refringence the 1st circularly polarized light of wavelength X 1, high molecule liquid crystal grating 13 and compaction material 14 and get final product.

Also have, under the situation of sawtooth wave section configuration, the recess depths d of high molecule liquid crystal grating 13 satisfies

d＝λ1/Δn1(λ1) ……(7)

Time+1 time diffraction efficiency is maximum.

[2]. about the incident light of the 2nd circularly polarized light

On the other hand, for the incident light of the 2nd circularly polarized light, even under the situation of the arbitrary wavelength in wavelength X 1 and the wavelength X 2, as mentioned above,, high molecule liquid crystal grating 13 is very little numerical value with the refractive indices n2 (λ 1) and the Δ n2 (λ 2) of compaction material 14 according to formula (5).Therefore shown in the compound expression of Fig. 2 (B), even any one wavelength in wavelength X 1 and the wavelength X 2 diffraction light does not take place yet and directly advances through polarization diffraction device 10.

As mentioned above, in the polarization diffraction device 10 shown in Figure 1, the cholesterol phase high molecule liquid crystal that employing will constitute high molecule liquid crystal grating 13 is processed into after the shape of grating, the structure of the compaction material 14 that constitutes by the optical isotropy material in the recess filling of this grating, but also can adopt other structure, for example adopt the such structure of the 2nd example that the following describes.

The 2nd example

Below just the polarization diffraction device of the present invention's the 2nd example be described below with sectional view shown in Figure 3.Also have, in this example, the part identical with the 1st example is marked with identical symbol and avoids repeat specification.

In the polarization diffraction device 20 of the 2nd example, as shown in Figure 3, be processed into after the grating that section is a concaveconvex shape (below be referred to as " isotropy grating ") 21 with the optics isotropic material, at least at the polymer-stabilized blue phase liquid crystal 22 of the recess filling of its grating, this point is different with the 1st example.

Isotropy grating 21 can directly be processed to form the surface of light-transmitting substrate 11, also can on light-transmitting substrate 11, form the organic material film of inorganic material such as SiON or polyimide and ultraviolet curable resin etc., utilize processing method to be processed into raster shape then.

On the other hand, be used in the material and the method for making of polymer-stabilized blue phase liquid crystal 22, as described in top background technology one hurdle, be recorded in non-patent literature 2, please refer to its explanation (specifically, reference example such as original text are 64～65 pages).

If adopt the polarization diffraction device 20 of the 2nd example, then polymer-stabilized blue phase liquid crystal 22 is because the width of reflected waveband R1 is narrower than cholesterol phase liquid crystal usually, therefore even under wavelength X 1 and the little situation in the wavelength interval of wavelength X 2, also can realize the polarization diffraction device that wavelength selectivity is arranged that the light utilization ratio is high.

Also have, in this example, use optical isotropy materials processing to become after the isotropy grating 21 of section as concaveconvex shape, at least at the polymer-stabilized blue phase liquid crystal 22 of its recess filling, but also can filling cholesterol phase liquid crystal 23 (in the 1st example shown in Figure 1, this cholesterol phase liquid crystal being used as high molecule liquid crystal grating 13).Also have, cholesterol phase liquid crystal at this moment can be a low molecular weight liquid crystal, can be high molecule liquid crystal also, and under the situation of low molecular weight liquid crystal, uses encapsulant (not shown) that liquid crystal is remained under the sealing state.

The 3rd example

Polarization diffraction device 50 with the present invention's the 3rd example of laminated wavelength selectivity diffraction element and phase-plate on the sectional view shown in Figure 4 polarization diffraction device 10 to the 1st example describes below.Also have, in this example, also the part identical with the 1st, the 2nd example is marked with identical symbol and avoids repeat specification.

The polarization diffraction device 50 of this example possesses integratedly, has the polarization diffraction device 10 of optical element (below be referred to as " phase element ") 40, wavelength selectivity diffraction element 30 and the 1st example of following phase-plate 43.Also has the holographic beam separation vessel that these wavelength selectivity diffraction elements 30 and polarization diffraction device 10 also can adopt high molecule liquid crystal grating 13 and grating 32 to be made of hologram pattern.

Wherein, wavelength selectivity diffraction element 30 possesses light-transmitting substrate 31, grating 32, compaction material 33 and light-transmitting substrate 34 (11).That is to say that the section configuration that forms, constitutes at the isotropic material that comprises organism pigment that has the light absorption end than wavelength X 1 short wave band is the grating (hereinafter referred to as " short wavelength's absorption grating ") 32 of periodicity concaveconvex shape on a side surface of light-transmitting substrate 31.Again, at the recess of this short wavelength's absorption grating 32, filling has the refractive index identical with short wavelength's absorption grating 32 to the light of wavelength X 1, simultaneously the light of wavelength X 2 is had the compaction material 33 of the refractive index that is different from short wavelength's absorption grating 32.Again, the light-transmitting substrate 34 that on compaction material 33 outer surfaces, connects the double as light-transmitting substrate 11 of polarized light diffraction element 10.

The wavelength selectivity diffraction element 30 of Xing Chenging has the identical 26S Proteasome Structure and Function of the invention of the TOHKEMY 2002-318306 record that proposes with the applicant of this Shen (reference example as [0032]～[0038] and Fig. 1) like this.

On the other hand, phase element 40 possesses the light-transmitting substrate 42 of light-transmitting substrate 31 of dual-purpose wavelength selectivity diffraction element 30 and the phase-plate 43 that light-transmitting substrate 41 is seized on both sides by the arms.

Phase-plate 43 at least to the light of wavelength X 1 as the birefringent phase difference be pi/2 promptly the wavelength plate of 1/4 wavelength work.As this polarizer 43, inorganic birefringent materials such as crystal or rutile crystallization can be processed as tabular uses, also polycarbonate film can be extended and make its discovery have birefringenct property to use, can also adopt direction of orientation organic birefringent material such as consistent liquid crystal or high molecule liquid crystal in face.Can be again laminated, make its slow axis direction form the angle of regulation, the phase-plate 43 that works as 1/4 wavelength plate for wavelength X 1 and wavelength X 2 by two kinds of birefringent materials that the birefringent phase difference is different.In this case, the incident light with the linearly polarized light of wavelength X 1 and wavelength X 2 all becomes circularly polarized light.Also have, in the polarization diffraction device 50 of this example, express the example of the phase-plate 43 that high molecule liquid crystal that wavelength X 1 and wavelength X 2 are worked as 1/4 wavelength plate constitutes.

Effect to the polarization diffraction device 50 of this example describes below.

(1) about the light of wavelength X 1

In the polarization diffraction device 50 that obtains like this, the linearly polarized light of wavelength X 1 with plane of polarization of Y direction, when light-transmitting substrate 41 1 sides are parallel to the incident of Z direction, incide wavelength selectivity diffraction element 30 after being transformed to the 2nd circularly polarized light with phase-plate 43.Because the light of 33 pairs of these wavelength X 1 of short wavelength's absorption grating 32 and compaction material has identical refractive index, diffraction does not take place here and directly advances to see through in the light of wavelength X 1, injects polarization diffraction device 10.Then, diffraction does not take place and directly advance to see through and penetrate from light-transmitting substrate 12 1 sides at this polarization diffraction device 10 shown in Fig. 2 (B) in the light of this wavelength X 1.

The 1st circularly polarized light of wavelength X 1 (the 1st circularly polarized light here is that the 2nd circularly polarized light is reflecting to form on the CD D (with reference to Fig. 5)) is during from light-transmitting substrate 12 1 side directive polarization diffraction devices 10, shown in Fig. 2 (A), diffraction light takes place in the concave depth d corresponding to the high molecule liquid crystal grating 13 of polarization diffraction device 10, injects wavelength selectivity diffraction element 30.These diffraction lights are only having the wavelength selectivity diffraction element 30 of diffraction function diffraction not to take place to wavelength X 2 and are seeing through, and be formed on the linearly polarized light that X-direction has plane of polarization through phase-plate 43 owing to be wavelength X 1, penetrate from light-transmitting substrate 41 1 sides.

Therefore, injecting from light-transmitting substrate 41 1 sides under the situation of linearly polarized light of wavelength X 1 that Y direction has plane of polarization, be transformed to the 2nd circularly polarized light with the polarization diffraction device 50 (phase-plate 43) of this example, the harmless lost territory of light is directly advanced to see through.And the 2nd circularly polarized light become the 1st circularly polarized light from light-transmitting substrate 12 1 sides once more during incident by reflectings surface such as CD D reflections, diffraction takes place at polarization diffraction device 10, at phase-plate 43 be formed on linearly polarized light that plane of polarization X-direction on arranged, penetrate from light-transmitting substrate 41 1 sides then thereafter.

(II) about the light of wavelength X 2

On the other hand, the linearly polarized light of wavelength X 2 that has plane of polarization in X-axis and Y direction is during from light-transmitting substrate 41 1 side direction Z direction incidents, the linearly polarized light of this wavelength X 2 is transformed to the 1st or the 2nd circularly polarized light by phase-plate 43, injects wavelength selectivity diffraction element 30 then.But in this wavelength selectivity diffraction element 30, for the light of wavelength X 2, short wavelength's absorption grating 32 is different with the refractive index of compaction material 33.Therefore corresponding to the concave depth of short wavelength's absorption grating 32, ± 1 diffraction light also takes place in addition directly advancing transmitted light (0 diffraction light).

Secondly, these diffraction lights are owing to be the light of wavelength X 2, in case inject and only have wavelength X of making 1 polarization diffraction device 10 that the function of diffraction takes place (the 1st circularly polarized light), the the 1st or the 2nd circularly polarized light is all as Fig. 2 (A) or (B), diffraction does not take place and sees through and penetrates from light-transmitting substrate 12 1 sides.

Thereafter, in a single day the circularly polarized light of wavelength X 2 is reflected by reflectings surface such as CDs, and the 1st circularly polarized light just becomes the 2nd circularly polarized light, and the 2nd circularly polarized light just becomes the 1st circularly polarized light.And diffraction does not take place at polarization diffraction device 10 and just directly advances to see through in case inject from light-transmitting substrate 12 1 sides in the circularly polarized light of this wavelength X 2.Thereafter, at wavelength selectivity diffraction element 30 diffraction taking place, and penetrates from light-transmitting substrate 41 1 sides at the linearly polarized light that phase-plate 43 becomes (Y direction or X-direction) plane of polarization vertical when having with incident.

Thereby for the linear polarization incident light of wavelength X 1, polarization diffraction device 10 works as the polarizing diffraction grating, and for the linear polarization incident light of wavelength X 2,30 conducts of wavelength selectivity diffraction element are worked with the diffraction element that the polarization of incident light state has nothing to do.Again, the light of the wavelength X 1 of the polarization diffraction device back and forth 50 by this example and wavelength X 2 becomes the linearly polarized light of the plane of polarization vertical with former linearly polarized light.

The 4th example

Describe the optic probe device of the present invention 60 of configuration polarization diffraction device 50 shown in Figure 4 below in detail with Fig. 5 of the configuration structure that schematically shows optic probe device 60 of the present invention.

The optic probe device 60 of this example possesses semiconductor laser 1 and photodetector 2, polarization diffraction device 50, collimation lens 3 and object lens 4, the structure that formation can be write down and reset CD D.

Semiconductor laser 1 is by having two luminous points that the wavelength X 1 and the wavelength X 2 of plane of polarization are arranged in Y direction, is used to switch the wavelength X 1 of emergent light and 2 wavelength of λ 2 constitute with semiconductor laser.This semiconductor laser (hereinafter referred to as " 2 wavelength semiconductor laser ") the 1st, emission wavelength lambda 1 are the laser of DVD wave band of 660nm ± 20nm and wavelength X 2 laser instrument for the laser of the CD wave band of 790nm ± 20nm, and each lasing fluorescence point is configured on the interval about 100 microns.

Also have, this 2 wavelength is with semiconductor laser 1, and in photodetector 2 was disposed at single component U, as the polarization diffraction device 50 of the 3rd example of the present invention, the light unit of injecting a side of ejaculation as the light that is disposed at this assembly U in aggregates used.

Effect to the optic probe device 60 of this example describes below.

Penetrate with semiconductor laser 1 from 2 wavelength, directly advancing through the wavelength X 1 of polarization diffraction device 50 and the diverging light of λ 2 utilizes collimation lens 3 to form the light of almost parallel, utilize object lens 4 to converge on the information recording surface of CD D, on this information recording surface, reflect to form back light.The diffraction that this back light is subjected to polarization diffraction device 50 is drawn towards the sensitive surface of photodetector 2, and the recorded information of CD D is transformed to electric signal.

I) situation of the linear polarization of wavelength X 1.

Specifically, the Y direction that penetrates with semiconductor laser 1 from 2 wavelength has the phase-plate 43 of linearly polarized light in polarization diffraction device 50 of wavelength X 1 of plane of polarization and becomes the 2nd circularly polarized light.Thereafter the 2nd circularly polarized light all directly advances through polarization diffraction device 50, converges on the information recording surface of the CD D that DVD uses, reflects to form the 1st polarized light simultaneously, injects polarization diffraction device 50 once again.

Thereafter, the 1st circularly polarized light (back light) of this wavelength X 1 is by polarization diffraction device 10 (with reference to Fig. 4) diffraction in the polarization diffraction device 50, and one time diffraction light is converged on the sensitive surface of photodetector 2.Again, in the 1st circularly polarized light (back light) of this wavelength X 1,0 diffraction light that directly advances through polarization diffraction device 10 is formed on the linearly polarized light that X-direction has plane of polarization, to the luminous point incident of 2 wavelength with semiconductor laser 1.

The ii) situation of the linearly polarized light of wavelength X 2

On the other hand, penetrate with semiconductor laser 1 from 2 wavelength, inject in the linearly polarized light of the wavelength X 2 that has plane of polarization on the Y direction of polarization diffraction device 50, by wavelength selectivity diffraction element 30 (with reference to Fig. 4) diffraction in the polarization diffraction device 50 ± 1 diffraction light can not converge on the information recording surface of the CD D that CD uses by collimation lens 3 and object lens 4.

On the other hand, in the linearly polarized light of above-mentioned wavelength X 2,0 light (this 0 diffraction light has also formed the 2nd circularly polarized light at phase-plate 43) that polarization diffraction device 10 is directly advanced to see through is converged on the information recording surface of the CD D that CD uses by collimation lens 3 and object lens 4, form the 1st circularly polarized light after being reflected and inject polarizer 50 once again, see through polarization diffraction device 10.

Thereafter, the part of the incident light of this wavelength X 2 is by wavelength selectivity diffraction element 30 diffraction in the polarization diffraction device 50, and 1 time diffraction light is converged on the sensitive surface of photodetector 2.Also have, 0 diffraction light that directly advances transmitted light in the conduct of wavelength selectivity diffraction element 30 is formed on the luminous point that X-direction has the linearly polarized light directive 2 wavelength usefulness semiconductor laser 1 of plane of polarization.

Thereby, polarization diffraction device 50 works as polarization beam splitter as described below, promptly DVD is worked as the polarizing diffraction grating with wavelength X 1, do not losing, on the return road of assembling to photodetector 2, can access high-diffraction efficiency simultaneously to the past road of CD D optically focused glazing.

Again, wavelength X 2 conducts that 50 couples of CD of this polarization diffraction device use are worked with the diffraction grating that the polarization of incident light state has nothing to do, because thick 2 times of using than DVD of overlayer, therefore the CD D that uses for the bigger CD of remaining birefringence, diffraction efficiency is not change also, therefore can be as realizing that the beam splitter that stable light detects works.

If adopt this polarization diffraction device 50, can make the grating pattern of polarization diffraction device 10 and wavelength selectivity diffraction element 30 to wavelength X 1 and wavelength X 2 independently, so can control angle of diffraction and diffraction efficiency again.Consequently, use 2 wavelength are configured in single light unit in the assembly U with semiconductor laser 1 and the shared photodetector 2 of DVD/CD, can realize DVD with and stable recording and the playback of CD usefulness CD D.

Also have, form the linearly polarized light of the polarization direction vertical to 2 wavelength with the light that the luminous point of semiconductor laser 1 returns, so can avoid and the interference of light of vibrating, so can access the emergent light intensity of stable laser with oscillation light.

In this example, to using the optic probe device 60 that polarized light diffraction element 10, wavelength selectivity diffraction element 30, phase element 40 are formed the polarization diffraction device 50 of one to be illustrated, still also can adopt structure with each key element separate configuration.Also have, in the optic probe device of reality, use the actuator of mobile object lens on Y-axis and Z-direction and the diffraction grating of the generation diffraction light that tracking is controlled usefulness etc., but owing to do not have direct relation with the present invention, so omit its explanation.

Again, in order to obtain focus signal and tracking signal, the sensitive surface of photodetector 2 is split into a plurality of, often the grating pattern of polarization diffraction device 10 and wavelength selectivity diffraction element 30 is spatially cut apart use, the feasible diffraction light of assembling polarization diffraction device 50 respectively on each sensitive surface.

In above-mentioned example, the diffraction grating of section configuration for the periodicity concaveconvex shape is illustrated, still be not limited to the structure of diffraction grating, for example also can adopt the element of thickness space distribution in face of optical activity materials such as cholesterol phase liquid crystal.In this case, form according to the film thickness distribution of optical activity material and only make wavelength that the transmission corrugated of the 1st circularly polarized light composition changes and wavefront transformation element with polarization selectivity at specific band.

The 5th example

Below with sectional view explanation shown in Figure 6 polarization diffraction device as the present invention's the 5th example.Also have, in this example, the part identical with the 1st example is marked with identical symbol and avoids repeat specification.

In the polarization diffraction device 70 of the 5th example, the material that forms the high molecule liquid crystal grating uses the cholesterol phase high molecule liquid crystal with pitch shorter than example 1, and this point is different.

For leaving by the light of the above-mentioned reflected waveband of pitch decision transmission peak wavelength λ 2 enough far away and the light of transmission peak wavelength λ 3, the refractive index of the 1st circularly polarized light and the 2nd circularly polarized light about equally.And than reflected waveband short wavelength's a side more, take place with than its more long wavelength's a side compare relatively large refringence.For example than reflected waveband more the wavelength of short wavelength's a side be designated as λ 1, the wavelength of long wavelength one side more much longer than reflected waveband is designated as λ 2 and λ 3, be designated as n1 (λ) with top described the same refractive index for the 1st circularly polarized light with cholesterol phase high molecule liquid crystal, to be designated as n2 (λ) for the refractive index of the 2nd circularly polarized light, if its poor (refringence) is designated as Δ n12 (λ), promptly

Δ n12 (λ)=| n1 (λ)-n2 (λ) |, then

I) be little numerical value for the refractive indices n12 (λ 2) of wavelength X 2 and λ 3 and Δ n12 (λ 3), promptly near 0

Δn12(λ2)＝|n1(λ2)-n2(λ2)|

≈0 ……(8)

Δn12(λ3)＝|n1(λ3)-n2(λ3)|

≈?0 ……(9)

But, Δ n12 (λ 2)＞Δ n12 (λ 3)

Be bigger value at the refractive indices n12 (λ 1) of wavelength X 1, promptly ii) again,

Δn12(λ1)＝|n1(λ1)-n2(λ1)|

＞Δn12(λ2) ……(10)

Identical with the 1st example, to what on light-transmitting substrate 11, form, the cholesterol phase high molecule liquid crystal that constitutes high molecule liquid crystal grating 73 is processed, forming section is concavo-convex clathrate, recess depths is the grating of d, carries out filling with transparent compaction material 74, at least the recess of the above-mentioned high molecule liquid crystal grating 73 of landfill, connect, clip light-transmitting substrate 12 from this compaction material 74 simultaneously, form polarization diffraction device 70.This filling member 74 uses to have in the incident light of wavelength X 1, λ 2 and λ 3 and the cholesterol member that constitutes for the isotropy optical material of the refractive index refractive index about equally of the 2nd circularly polarized light of high molecule liquid crystal mutually.

By means of this, in the incident light of wavelength X 1, λ 2 and λ 3, high molecule liquid crystal grating 73 and the refringence of compaction material 74 for the 1st circularly polarized light are equivalent to described refractive indices n12 (λ 1), Δ n12 (λ 2) and the Δ n12 (λ 3) of cholesterol phase high molecule liquid crystal with respect to the 1st circularly polarized light and the 2nd circularly polarized light.

[1]. about the incident light of the 1st circularly polarized light

I) that is to say, with respect to the 1st circularly polarized light of wavelength X 1, high molecule liquid crystal grating 73 and the refractive indices n1 (λ 1) of compaction material 74 be equivalent to cholesterol mutually high molecule liquid crystal for the described refractive indices n12 (λ 1) of the 1st and the 2nd circularly polarized light of wavelength X 1, promptly

Δn1(λ1)＝Δn12(λ1)

＝|n1(λ1)-n2(λ1)|

＞Δ n12 (λ 2) (according to formula (10)) ... (11)

Ii) same, for the 1st circularly polarized light of wavelength X 2, wavelength X 3, high molecule liquid crystal grating 73 and refractive indices n1 (λ 2), the Δ n1 (λ 3) of compaction material 74 be equivalent to cholesterol mutually high molecule liquid crystal with respect to the above-mentioned refractive indices n12 (λ 2) of the 1st and the 2nd circularly polarized light and Δ n12 (λ 3), just

Δn1(λ2)＝Δn12(λ2)

＝|n1(λ2)-n2(λ2)|

≈ 0 (according to formula (8)) ... (12)

And

Δn1(λ3)＝Δn12(λ3)

＝|n1(λ3)-n2(λ3)|

≈ 0 (according to formula (9)) ... (13)

Also have, Δ n1 (λ 2) and Δ n1 (λ 3) are if the value below 20% of above-mentioned Δ n1 (λ 1) we can say then that in wavelength X 2 and wavelength X 3 refringence of high molecule liquid crystal grating 73 and compaction material 74 about equally.

[2] about the incident light of the 2nd circularly polarized light

Again, in the incident light of wavelength X 1, wavelength X 2 and wavelength X 3, for the 2nd circularly polarized light, refractive indices n2 (λ 1), Δ n2 (λ 2) and the Δ n2 (λ 3) of high molecule liquid crystal grating 73 and compaction material 74 do not take place.That is to say,

Δn2(λ1)＝Δn2(λ2)＝Δn2(λ3)

≈0 ……(14)

With Fig. 7 the effect of the polarization diffraction device 70 of the 5th example is described below.

[1]. about the incident light of the 1st circularly polarized light

For the incident light of the 1st circularly polarized light,

I) for example for wavelength X 2 and wavelength X 3, the refractive indices n1 (λ 2) and the Δ n1 (λ 3) of high molecule liquid crystal grating 73 and compaction material 74 are to approach 0 fractional value according to formula (12) and formula (13).Therefore shown in Fig. 7 (A), diffraction light does not take place, but directly advance through polarization diffraction device 70.

Ii) again, for wavelength X 1, it is limited numerical value that this refractive indices n1 (λ 1) draws according to formula (11), therefore shown in Fig. 7 (A) diffraction light takes place.At this moment, for make to wavelength X 1 ± 1 diffraction efficiency is for maximum, and following formula is arranged

d＝λ1/(2·Δn1(λ1)) ……(15)

Wherein,

D: the recess depths of high molecule liquid crystal grating 73

Δ n1 (λ 1): the recess depths d of the high molecule liquid crystal grating 73 that cholesterol phase high molecule liquid crystal is constituted processes, and makes to be met for refringence the 1st circularly polarized light of wavelength X 1, high molecule liquid crystal grating 73 and compaction material 74 to get final product.

Also have, under the situation of sawtooth wave section configuration, the recess depths d of high molecule liquid crystal grating 73 satisfies

d＝λ1/Δn1(λ1) ……(16)

It is maximum that time+1 time diffraction efficiency reaches.

[2]. about the incident light of the 2nd circularly polarized light

On the other hand, incident light for the 2nd circularly polarized light, under the situation of arbitrary wavelength of wavelength X 1, wavelength X 2 and wavelength X 3, high molecule liquid crystal grating 73 is minimum numerical value with refractive indices n2 (λ 1), Δ n2 (λ 2), the Δ n2 (λ 3) of compaction material 74 according to formula (4) as can be known as mentioned above.Therefore shown in the compound expression of Fig. 7 (B), diffraction light does not take place for arbitrary wavelength of wavelength X 1, wavelength X 2 and wavelength X 3, directly advance through polarization diffraction device 70.

The 6th example

Describe with sectional view shown in Figure 8 polarization diffraction device below the present invention's the 6th example.Also have, in this example, the part identical with the 1st example is marked with identical symbol and avoids repeat specification.

In the polarization diffraction device 80 of the 6th example, the compaction material of the compaction material different refractivity of employing of the material of filling high molecule liquid crystal grating and example 5, this point is different from example 5.

With top described identical, cholesterol phase high molecule liquid crystal is designated as n1 (λ) to the refractive index of the 1st circularly polarized light, will be designated as n2 (λ) to the refractive index of the 2nd circularly polarized light, the refractive index of compaction material is designated as ns (λ).For the 1st circularly polarized light and the 2nd circularly polarized light, be designated as Δ n respectively with the refringence of compaction material _1-S(λ), Δ n _2-S(λ).Just

Δn _1-S(λ)＝|n1(λ)-ns(λ)|

Δn _2-S(λ)＝|n2(λ)-ns(λ)|

Select to make refractive index n 1 (λ 1) roughly consistent in wavelength X 1 with refractive index n s (λ 1) for the compaction material of wavelength X 1 for the 1st circularly polarized light.

I) at compaction material and the high molecule liquid crystal grating index difference Δ n of wavelength X 1 for the 1st circularly polarized light and the 2nd circularly polarized light _1-S(λ), Δ n _2-SBeing to approach 0 very little numerical value for the 1st circularly polarized light (λ), for the 2nd circularly polarized light, according to formula (11), is significant value, promptly

Δn _1-S(λ1)＝|n1(λ1)-ns(λ1)|≈0 ……(17)

Δn _2-S(λ1)＝|n2(λ1)-ns(λ1)|＞Δn _1-S(λ1) ……(18)

Ii) again, at the compaction material and the high molecule liquid crystal grating index difference Δ n for the 1st circularly polarized light and the 2nd circularly polarized light of wavelength X 2 and wavelength X 3 _1-S(λ), Δ n _2-S(λ) according to formula (12) and formula (13), have about equally significant numerical value, be

Δn _1-S(λ2)＝|n1(λ2)-ns(λ2)|

≈|n2(λ2)-ns(λ2)|

＝Δn _2-S(λ2) ……(19)

Δn _1-S(λ3)＝|n1(λ3)-ns(λ3)|

≈|n2(λ3)-ns(λ3)|

＝Δn _2-S(λ3) ……(20)

Identical with the 1st example, to being formed on the light-transmitting substrate 11, the cholesterol phase high molecule liquid crystal that constitutes high molecule liquid crystal grating 83 is processed, making its section is that the recess depths of concavo-convex lattice shape and grid is d, carry out filling with transparent compaction material 84, to the recess of the above-mentioned high molecule liquid crystal grating 83 of major general landfill in addition, connect and clip light-transmitting substrate 12 from this compaction material 84 simultaneously, as polarization diffraction device 80, this compaction material 84 uses to have under the situation of the incident light of wavelength X 1 and cholesterol high molecule liquid crystal compaction material that the isotropy optical material of the refractive index refractive index about equally of the 1st circularly polarized light is constituted mutually.

Like this, in the incident light of wavelength X 1, λ 2 and wavelength X 3, be equivalent to Δ n for the high molecule liquid crystal grating 83 of the 1st circularly polarized light and the refringence of compaction material 84 _1-S(λ 1), Δ n _1-S(λ 2) and Δ n _1-S(λ 3) are equivalent to Δ n for the high molecule liquid crystal grating 83 of the 2nd circularly polarized light and the refringence of compaction material 84 _2-S(λ 1), Δ n _2-S(λ 2) and Δ n _2-S(λ 3).

With Fig. 9 in this case effect is described below.

[1]. about the incident light of the 1st circularly polarized light

For the 1st circularly polarized light incident light,

I) for example for wavelength X 1, the refractive indices n of high molecule liquid crystal grating 83 and compaction material 84 _1-S(λ 1) as the formula (17), for approaching 0 very little value.Therefore shown in Fig. 9 (A), diffraction light does not take place just directly advance through polarization diffraction device 80.

Ii) and for wavelength X 2 and λ 3, its refractive indices n _1-S(λ 2) and Δ n _1-S(λ 3) are limited numerical value suc as formula shown in (19) and the formula (20), therefore shown in Fig. 9 (A), diffraction light take place.

[2]. about the 2nd circularly polarized incident light

On the other hand, for the 2nd circularly polarized incident light, under the situation of any one wavelength of wavelength X 1, wavelength X 2 and wavelength X 3, the refractive indices n of high molecule liquid crystal grating 83 and compaction material 84 _2-S(λ 1), Δ n _2-S(λ 2) and Δ n _2-S(λ 3) have significant numerical value.Therefore go up shown in the compound expression as Fig. 9 (B), diffraction light all takes place at polarization diffraction device 80 in any one wavelength of wavelength X 1, wavelength X 2 and wavelength X 3.

By forming this structure, can realize to the 1st circularly polarized light having only a wavelength in the wavelength of incident that the element of diffraction light does not take place.

The 7th example

Describe with sectional view shown in Figure 10 polarization diffraction device below the present invention's the 7th example.Also have, in this example, the part identical with the 1st example is marked with identical symbol and avoids repeat specification.

In the polarization diffraction device 90 of the 7th example, the material that the high molecule liquid crystal grating forms usefulness adopts has the cholesterol high molecule liquid crystal mutually that is different from the example 1 and the pitch of example 5, and this point is different with it.

For the refractive index that also keeps transmission peak wavelength λ 3, the 1 circularly polarized lights of abundant distance and the 2nd circularly polarized light with above-mentioned generation wave band about equally by pitch decision.And for the transmission peak wavelength λ 1 of a side shorter than reflected waveband wavelength and than the transmission peak wavelength λ 2 near long wavelength's one side of reflected waveband, take place to compare relatively large refringence with transmission peak wavelength λ 3.With top described identical, the refractive index to the 1st circularly polarized light of cholesterol phase high molecule liquid crystal is designated as n1 (λ), will be designated as n2 (λ) for the refractive index of the 2nd circularly polarized light, its refringence is designated as Δ n12 (λ), promptly

Δ n12 (λ)=| n1 (λ)-n2 (λ) | the time,

I) at the refractive indices n12 (λ 3) of wavelength X 3 for to approach 0 very little value, promptly

Δn12(λ3)＝|n1(λ3)-n2(λ3)|

≈0 ……(21)

Ii) again, for wavelength X 1 and wavelength X 2, its refractive indices n12 (λ 1) and Δ n12 (λ 2) have bigger value, are

Δn12(λ1)＝|n1(λ1)-n2(λ1)|

＞Δn12(λ3) ……(22)

Δn12(λ2)＝|n1(λ2)-n2(λ2)|

＞|n12(λ3) ……(23)

The same with the 1st example, to what on light-transmitting substrate 11, form, the cholesterol phase high molecule liquid crystal that constitutes high molecule liquid crystal grating 93 is processed, forming section is concavo-convex lattice shape, recess depths is the grating of d, at least the recess of above-mentioned high molecule liquid crystal grating 93 is carried out filling with transparent compaction material 94, connect and clip light-transmitting substrate 12 from this compaction material 94 simultaneously, as polarization diffraction device 90.This compaction material 94 adopts to have with under the condition of the incident light of wavelength X 1, wavelength X 2 and wavelength X 3, the material that constitutes for the optical isotropy material of the roughly the same refractive index of the refractive index of the cholesterol phase high molecule liquid crystal of the 2nd circularly polarized light.

By means of this, in the incident light of wavelength X 1, wavelength X 2 and wavelength X 3, be equivalent to for the cholesterol of the 1st circularly polarized light and the 2nd the circularly polarized light above-mentioned refractive indices n12 of high molecule liquid crystal (λ 1), Δ n12 (λ 2) and Δ n12 (λ 3) mutually for the high molecule liquid crystal grating 93 and the refringence of compaction material 94 of the 1st circularly polarized light.〕

Below with Figure 11 explanation effect in this case.

[1]. about the incident light of the 1st circularly polarized light

For the incident light of the 1st circularly polarized light,

I) for example for wavelength X 3, the refractive indices n1 (λ 3) of high molecule liquid crystal grating 93 and compaction material 84 as the formula (21), for approaching 0 very little value.Therefore shown in Figure 11 (A), diffraction light does not take place just directly advance through polarization diffraction device 90.

Ii) and for wavelength X 1 and λ 2, its refractive indices n1 (λ 1) and Δ n1 (λ 2) are limited numerical value suc as formula shown in (22) and the formula (23), therefore as Figure 11 (A) shown in, the generation diffraction light.

[2]. about the 2nd circularly polarized incident light

On the other hand, for the 2nd circularly polarized incident light, under the situation of any one wavelength of wavelength X 1, wavelength X 2 and wavelength X 3, all the same with above-mentioned example, high molecule liquid crystal grating 93 is very little with refractive indices n2 (λ 1), Δ n2 (λ 2) and the Δ n2 (λ 3) of compaction material 94.Therefore go up shown in the compound expression as Figure 11 (B), diffraction does not take place in any one wavelength of wavelength X 1, wavelength X 2 and wavelength X 3, and directly advances through polarization diffraction device 90.

By forming this structure, can realize having only a wavelength in the wavelength of incident no matter how the element of diffraction does not take place its polarization.

Polarizing diffraction grating of the present invention is to have maximum transmission, the grating of diffraction characteristic difference between the 1st circularly polarized light of incident and the 2nd circularly polarized light, and also has function as diffraction element for the linearly polarized light of incident.Effect in this case is that example describes with Figure 12 with the 5th example.

Linearly polarized light can be thought intensity the 1st circularly polarized light about equally and the addition of the 2nd circularly polarized light.Therefore the transmission diffraction characteristic that obtains also is the average characteristics of the 1st circularly polarized light and the 2nd circularly polarized light.That is to say, for wavelength X 1, shown in Figure 12 (A) and Figure 12 (B), for the 2nd linearly polarized light of the 1st linearly polarized light that is parallel to paper and vertical paper, all demonstrate with for the 1st circularly polarized light shown in Fig. 7 (A) and the suitable transmission diffraction characteristic of each transmission diffraction characteristic sum that takes place for the 2nd circularly polarized light shown in Fig. 7 (B).For wavelength X 1 and wavelength X 2, shown in Fig. 7 (A) and Fig. 7 (B), diffraction light does not take place in the 1st circularly polarized light and the 2nd circularly polarized light any one, therefore shown in Figure 12 (A) and Figure 12 (B), in the 1st linearly polarized light and the 2nd linearly polarized light any one diffraction light does not take place.

This transmission diffraction characteristic to linearly polarized light is not limited to the 1st linearly polarized light and the 2nd linearly polarized light, all demonstrates roughly the same diffraction characteristic for the linearly polarized light of going up in any direction polarization.Like this, under situation about linearly polarized light being used, correlativity polarization diffraction device and polarization is disappeared, only utilize wavelength selectivity as incident light.

For polarization diffraction device of the present invention and certain feature of using the optic probe device of this element, will utilize embodiment shown below to be specifically described.

Embodiment

Example 1

With regard to the polarization diffraction device 50 of present embodiment, utilize sectional view shown in Figure 4 that its method for making and structure are specifically described below.

[I]. about polarization diffraction device 10

(1) this polarization diffraction device 10 is the structure components identical that illustrate with above-mentioned the 1st example, as high molecule liquid crystal grating 13, normal light refractive index n o=1.51 behind the employing producing high-molecular and unusual optical index ne=1.71, the cholesterol phase high molecule liquid crystal of right-hand pitch P=3.8 micron, being processed into section is the rectangular grid shape.At this moment, cholesterol phase high molecule liquid crystal is for the right-circularly polarized light as the 1st circularly polarized light, and demonstrating centre wavelength is λ 0=612nm, the reflected waveband R1 of wave band 75nm.

(2) then, with having and this cholesterol compaction material 14 that constitutes of the transparent adhesives of the suitable refractive index of mean refractive index n=1.61 of high molecule liquid crystal mutually, the recess of landfill high molecule liquid crystal grating 13, connect simultaneously, be fixed on the light-transmitting substrate 12 of glass formation, make polarization diffraction device 10 with this.

Here, for the left circularly polarized light as the 2nd circularly polarized light, the refractive index n 2 (λ) of cholesterol phase high molecule liquid crystal approximates mean refractive index n greatly.According to using 4 * 4 Theoretical Calculation of transmitted light polarized component of propagating the cholesterol phase high molecule liquid crystal of matrix methods, the recess depths of high molecule liquid crystal grating 13 adopts the d=8.8 micron.By means of this, be approximately π as the right-circularly polarized light of the 1st circularly polarized light and phase differential for wavelength X 1=660nm as the transmitted light of the left circularly polarized light of the 2nd circularly polarized light, for wavelength X 2=790nm, be approximately 0.14 π.

Therefore, the protuberance of concaveconvex shape (high molecule liquid crystal grating 13) and the phase difference of the transmitted light of recess (compaction material 14), the phase differential of just calculating from following formula

φ＝2π·Δn(λ)·d/λ ……(24)

Wherein, Δ n (λ): refringence is equivalent to about π in wavelength X 1 for the right-circularly polarized light as the 1st circularly polarized light, for the left circularly polarized light as the 2nd circularly polarized light, for greater than 0.14 π.In wavelength X 2, all be approximately 0 for any circularly polarized light again.

In this polarization diffraction device 10,0 diffraction efficiency directly advancing transmission is utilized following formula to be similar to and is obtained.

η0＝cos ²(φ/2) ……(25)

± 1 diffraction efficiency

η1＝(2/π) ²·sin ²(φ/2) ……(26)

Therefore, the 1st circularly polarized light of wavelength X 1 is according to formula (26), ± 1 maximum η 1=41% of diffraction light, and the 2nd circularly polarized light not diffraction ground directly advances transmission (η 0=100%).Again, for the 1st circularly polarized light of wavelength X 2, according to formula (25), the maximum η 0=95% of 0 diffraction efficiency, for the 2nd circularly polarized light, η 0=100%, more than half light be diffraction and directly advance to see through not.

[II]. about wavelength selectivity diffraction element 30

(1) the red photoresist that is included in wavelength 590nm and has the organism pigment (red pigment) of absorption edge utilize rotating coating on the light-transmitting substrate 31 that glass constitutes evenly coating form to heat after 6.0 micron thickness and make its curing.

(2) then utilize photomask that red photoresist is carried out ultraviolet exposure and video picture processing, make short wavelength's absorption grating 32 that section is a rectangle with this.The refractive index of this short wavelength's absorption grating 32 is n1=1.654 in wavelength X 1, is n2=1.626 in wavelength X 2.

(3) then, be n1=1.656 with the refractive index after polymerization for wavelength X 1, for wavelength X 2 be the photopolymer of n2=1.646 with free state as compaction material 33 fillings in the recess of short wavelength's absorption grating 32.Thereafter the light-transmitting substrate 11 of laminated polarization diffraction device 10 on compaction material 33 clips compaction material 33 with short wavelength's absorption grating 32, and the monomer irradiation ultraviolet radiation is made its polymerization, makes wavelength selectivity diffraction element 30.

In the wavelength selectivity diffraction element of making like this 30, for wavelength X 1, do not have refringence between short wavelength's absorption grating 32 and the compaction material 33, so diffraction light does not take place and directly advance transmission.On the other hand, for wavelength X 2, the phase differential of the light that the protuberance of short wavelength's absorption grating 32 and recess pass through is approximately 0.30 π, and 0 diffraction efficiency directly advancing transmission is η 0=79% according to formula (25), and ± 1 diffraction efficiency is to be η 1=8.5% according to formula (26).Therefore, wavelength selectivity diffraction element 30 is irrespectively to make the incident light of wavelength X 1 directly advance to see through with the polarization of incident light state, makes the wavelength selectivity diffraction element of 8.5% ± 1 diffraction in the incident light of wavelength X 2.

[III]. about phase element 40

The 2nd high molecule liquid crystal (omitting among the figure) that will be equivalent to the 1st high molecule liquid crystal (omitting among the figure) of length of delay 362.5nm of π and pi/2 and length of delay 181.3nm for the birefringent phase difference of wavelength X 1 and the central wavelength lambda c=725nm of wavelength X 2 is laminated on the light-transmitting substrate 41 that glass constitutes according to the order of the 1st high molecule liquid crystal, the 2nd high molecule liquid crystal, and make each slow axis angle relative Y-axis in the XY face form 15 ° and 75 °, make phase element 40.

During from light-transmitting substrate 41 1 side incidents, transmitted light forms the left-hand polarization light as the 2nd circularly polarized light to this phase element 40 at the linearly polarized light of wavelength X 1 that has plane of polarization on the Y direction and wavelength X 2.Again, phase element 40 is as the right-handed polarized light of the 1st circularly polarized light during from light-transmitting substrate 42 1 side incidents, and transmitted light forms the linearly polarized light that all has plane of polarization on X-direction.That is to say that this phase element 40 works as 1/4 wavelength plate for wavelength X 1 and wavelength X 2.

By like this, can make the polarization diffraction device 50 of the present embodiment of the phase element 40 that will have phase-plate 43, wavelength selectivity diffraction element 30, polarization diffraction device 10 laminated formation, obtain the optical function that in above-mentioned the 3rd example, illustrates.

Example 2

Optic probe device 60 to polarization diffraction device 50 is housed describes with reference to the Fig. 5 that schematically shows its configuration structure below.

This polarization diffraction device 50 works as the polarizing diffraction grating for the wavelength X 1 that DVD uses, and the light loss that the control diffraction light causes on the road converging on the CD D realizes the light utilization ratio more than 90%.On the other hand, this polarization diffraction device 50 works as the polarization beam splitter that can access the height ± 1 time diffraction efficiency more than 30% on the return road that converges at photodetector 2.

Again, this polarization diffraction device 50, the wavelength X of using for CD 2 be as working with the irrelevant diffraction grating of polarization of incident light state, for remaining birefringent CD CD D arranged, diffraction efficiency is not change also, therefore can be as realizing that the beam splitter that stable light detects works.

Consequently, in miniaturization, the light-weighted while of realizing optic probe device 60, can realize to DVD with and stable recording and the playback of the CD D that uses of CD.

Example 3

With regard to the polarization diffraction device 70 of present embodiment, its method for making and structure are specifically described below with sectional view shown in Figure 6.

[I]. about polarization diffraction device 70

I) this polarization diffraction device 70 is and the 5th example structure components identical, as high molecule liquid crystal grating 73, adopt producing high-molecular normal light refractive index n o=1.55 afterwards, and unusual optical index ne=1.77, the cholesterol phase high molecule liquid crystal of right-hand pitch P=0.33 micron, being processed into section is the rectangular grid shape.At this moment, cholesterol phase high molecule liquid crystal demonstrates the reflected waveband R1 of wave band 70nm for the right-circularly polarized light central wavelength lambda 0=550nm as the 1st circularly polarized light.

Ii) follow the recess of the compaction material 74 landfill high molecule liquid crystal gratings 73 of the transparent adhesives formation of using refractive index with the mean refractive index n=1.66 that is equivalent to this cholesterol phase high molecule liquid crystal, simultaneously bonding, be fixed on the light-transmitting substrate 12 that glass constitutes, make polarization diffraction device 70 with this.

Here, the refractive index n 2 (λ) for as the cholesterol phase high molecule liquid crystal of the left-hand polarization light of the 2nd circularly polarized light approximates mean refractive index n greatly.According to adopting 4 * 4 propagation matrix method, the Theoretical Calculation of the transmitted light polarized component of cholesterol phase high molecule liquid crystal, the recess depths d of high molecule liquid crystal grating 73 adopts the d=9.1 micron.Like this, be approximately π as the right-circularly polarized light of the 1st circularly polarized light and transmitted light phase differential for wavelength X 1=405nm,, be approximately 0.12 π for wavelength X 2=660nm as the left circularly polarized light of the 2nd circularly polarized light, for wavelength X 3=790nm, be approximately 0.05 π.

Therefore, the protuberance of concaveconvex shape (high molecule liquid crystal grating 73) and the phase difference of the transmitted light of recess (compaction material 74), the phase differential that just calculates from following formula

φ＝2π·Δn(λ)·d/λ ……(27)

Wherein, Δ n (λ): refringence, in wavelength X 1, be equivalent to about π for right-handed polarized light as the 1st circularly polarized light, in wavelength X 2 and wavelength X 3, be approximately 0.10 π and about 0.05 π respectively.In the 2nd circularly polarized light, all be approximately 0 for arbitrary wavelength.

In this polarization diffraction device 70, directly advance 0 diffraction efficiency of transmission and can obtain, promptly with following formula is approximate

η0＝cos ²(φ/2) ……(28)

± 1 time diffraction efficiency can be obtained with following formula is approximate, promptly

η1＝(2/π) ²sin ²(φ/2) ……(29)

Therefore, the 1st circularly polarized light of wavelength X 1 is according to formula (29), and ± 1 time diffraction light is maximum η 1=41%, and the 2nd circularly polarized light diffraction does not take place and directly advances transmission (η 0=100%).Again, for the 1st circularly polarized light of wavelength X 2 and wavelength X 3, according to formula (28), 0 time diffraction efficiency is respectively maximum η 0=96%, and η 0=98% is η 0=100% for the 2nd circularly polarized light, and the light that does not have diffraction just directly to advance to see through accounts for a greater part of.

Example 4

Optic probe device 100 to polarized light diffraction element 70 is housed describes with reference to the Figure 13 that schematically shows its configuration structure below.

Optic probe device 100 adopt replacing emission wavelength lambda 1 for the high density compact disc of 405nm ± 10nm with laser, wavelength X 2 for the laser of the DVD wave band of 660nm ± 20nm, wavelength X 3 for 3 wavelength of the laser of the CD wave band of 790nm ± 20nm with laser semiconductor laser instrument 5.And the polarizer that comprises in the polarization diffraction device shown in the embodiment 2 50 uses for wavelength X 1, wavelength X 2 and wavelength X 3 as the big polarizer of wavelength coverage that about 1/4 polarizer works, and newly appends polarizing diffraction grating 70.

The function of the wavelength X 3 that wavelength X 2 that embodiment 2 illustrated DVD use and CD use, also roughly the same at embodiment 4, therefore omit its explanation.

The polarization diffraction device 70 that newly appends, work as the polarizing diffraction grating for the Wavelength of Laser λ 1 that in high density compact disc, uses, be concentrated on CD D on the road, the light loss that diffraction light causes is controlled, can realize the utilization ratio more than 90%.On the other hand, this polarization diffraction device 70 works as the polarization beam splitter that can access the height ± 1 time diffraction efficiency more than 30% on the return road that is concentrated on photodetector 2.Again, this polarization diffraction device 70, the wavelength X 3 that wavelength X of using for DVD 2 and CD use is not no matter diffraction light how, takes place in the polarization of incident light state.

Consequently, can realize the miniaturization and the lightweight of optic probe device 100, can realize simultaneously to high density compact disc with, DVD with and stable recording and the playback of the CD D that uses of CD.

The polymerism cholesterol phase liquid crystal that is used to the formation cholesterol phase high molecule liquid crystal of polarization diffraction element of the present invention can use known optically active compound.For example, the Jap.P. spy who is preferably formula (30) opens the bigger compound of spiral induction force that 2002-12580 discloses.

R-X1-A1-B1-C*HY1-CH ₂-(B2)n-X2-A2-X3-A3-X4-Z-OCO-CY2＝CH ₂

…(30)

The implication of the symbol in the formula (30) is as described below.

R: alkyl, hydrogen atom or the halogen atom of the carbon number 1～12 that the alkyl of carbon number 1～12, the hydrogen atom more than 1 or 1 are replaced by fluorine atom,

X1, X2, X4, X4: independent mutually, expression ketonic oxygen base (COO-), oxygen carbonyl (OCO-), etheric oxygen atom (O-), oxygen methylene (OCH ₂-), inferior methoxyl (CH ₂O-) or singly-bound,

Y1: methyl (CH ₃) or the methyl that replaced by fluorine atom of the hydrogen atom more than 1 or 1,

Y2: hydrogen atom or methyl (CH ₃),

Z: the alkylidene of the carbon number 1～12 that the alkylidene of carbon number 1～12 or the hydrogen atom more than 1 or 1 are replaced by fluorine atom,

A1, A3, A3: mutually independent, represent 1 or 2 hydrogen atoms can by fluorine atom replace 1,4-phenylene, 1 or 2 hydrogen atoms can be by methyl (CH ₃) replace 1, the 4-phenylene, do not have replace 2, the 6-naphthylene, do not have replace anti--1,4-cyclohexylidene or singly-bound,

B1, B2: mutually independent, represent 1 or 2 hydrogen atoms can by fluorine atom replace 1,4-phenylene, 1 or 2 hydrogen atoms can be by methyl (CH ₃) replace 1, the 4-phenylene, do not have replace 2, the 6-naphthylene, do not have replace anti--1, the 4-cyclohexylidene or-D1-CH ₂CH ₂(D1 and D2 are independent mutually, represent that 1 or 2 hydrogen atoms can be by fluorine atom and/or methyl (CH for the group that-D2-represents ₃) replace 1, the 4-phenylene, do not have replace 2, the 6-naphthylene, do not have replace anti--1,4-cyclohexylidene),

N:1 or 2,

C ^*: asymmetric carbon atom.

In addition, in order to adjust pitch, can and with other polymerizable liquid crystal compound.When other polymerizable liquid crystal compound had a plurality of polymerism functional group, the kind of polymerism functional group can be different.

The known compound that has 2 polymerism functional groups in a large number when making their polymerizations, generally can obtain good thermotolerance and strength characteristics, so be fit to adopt.But the following diacrylate ester compounds of putting down in writing in the concrete illustration Japanese patent laid-open 10-265531 communique,

In the formula, A ²Be fluorine atom, chlorine atom, hydrogen atom or methyl, q is 0～8 integer, q be 0 or 1 o'clock r be 0, the r when q is 2～8 integer is 1, X ²For singly-bound ,-COO-,-OCO-or-CH ₂CH ₂-, s is 0 or 1, and p is 0 or 1, and p is 0 o'clock X ³Be singly-bound, p is 1 o'clock X ³Structure and X ²Identical, used here symbol only refers to the symbol in this formula.

Specifically, but the following compound of illustration.

In addition, contain the compound of 1 polymerism functional group, can exemplify the compound that illustrative following formula is represented in the same communique as molecule,

In the formula, A ¹Be fluorine atom, chlorine atom, hydrogen atom or methyl, m is 0～8 integer, m be 0 or 1 o'clock n be 0, the n when m is 2～8 integer is 1, X ¹For singly-bound ,-COO-,-OCO-or-CH ₂CH ₂-, Y is 1,4-phenylene or 1, and 4-is anti--cyclohexylidene, Z ¹Be alkoxy, fluorine atom, chlorine atom or the cyano group of carbon number 1～8, used here symbol only refers to the symbol in this formula.

Specifically, but the following compound of illustration.

In addition, but the compound represented of illustration following formula also,

X in the formula is 1,4-phenylene or 1, and 4-is anti--cyclohexylidene, Y is the alkyl of carbon number 1～8.

Specifically, example comprises 4-(anti--4 '-n-pro-pyl cyclohexyl-carbonyl oxygen base) phenyl acrylate, 4-(anti--4 '-normal-butyl cyclohexyl-carbonyl oxygen base) phenyl acrylate, 4-(anti--4 '-n-pentyl cyclohexyl-carbonyl oxygen base) phenyl acrylate, 4-(4 '-n-pro-pyl phenyl ketonic oxygen base) phenyl acrylate, 4-(4 '-n-butylphenyl ketonic oxygen base) phenyl acrylate, 4-(4 '-n-pentyl phenyl ketonic oxygen base) phenyl acrylate preferably.These polymerizable liquid crystal compounds can also can be used in combination more than 2 kinds or 2 kinds in independent a kind of use.

In addition, be used to contain the non-liquid-crystal compounds of polymerism in the polymerism cholesterol phase liquid-crystal composition of polarization diffraction element of the present invention.This polymerizable compound is not particularly limited, is preferably acrylic ester, methacrylate ester, vinyl ether based compound, they can a kind use separately, also can be used in combination more than 2 kinds or 2 kinds.

For the storage stability with liquid crystal compounds of polymerizable group of the present invention is improved, can add stabilizing agent.As stabilizing agent, but illustration quinhydrones, quinhydrones one alkyl ether or tert-butyl catechol class etc.

The present invention is not limited in above-mentioned embodiment, can implement in every way under the prerequisite that does not break away from its technology essential factor.

Industrial applicability

Polarization diffraction device of the present invention, its diffraction efficiency has relevant with circular polarization at specific transmission wave band Characteristic, and at other transmission wave band and polarization irrelevant, therefore by raster shape and grating pattern are established Meter is adjusted, and can access wavelength selectivity and polarization choosing with the particular circle polarised light that only takes out specific band The beam splitter of selecting property.

Particularly by polarization diffraction device of the present invention being used in LASER Light Source with a plurality of wavelength to specification Different CDs carries out the optic probe device of information recording/or playback, can realize the miniaturization of optic probe device With, owing to form the high optical system of light utilization ratio, can realize stable record and playback simultaneously.

Claims (10)

1. polarization diffraction device, the light generation diffraction that it makes specific wavelength is characterized in that,

Described polarization diffraction device utilizes optical activity material and these two kinds of being connected to form diffraction grating of optical material of optical isotropy material and forms,

By using described optical activity material to become with a kind of materials processing in the described optical isotropy material after section configuration has the concavo-convex grating of periodicity, at least at the described optical activity material of recess filling of the described grating of this processing and the another kind of material in the described optical isotropy material and form described diffraction grating

Wherein this optical activity material has reflected waveband at the 1st circularly polarized light with a sense of rotation, and at a kind of circularly polarized light generation diffraction in the 1st circularly polarized light of the outer specific wavelength of this reflected waveband and sense of rotation the 2nd circularly polarized light opposite with the 1st circularly polarized light, and, it diffraction takes place is seen through at another circularly polarized light in described the 1st circularly polarized light and described the 2nd circularly polarized light.

2. polarization diffraction device, its for have respectively the 1st circularly polarized light and with the 1st wavelength X 1 of the 2nd circularly polarized light of the 1st circularly polarized light reverse direction rotation and the incident light that is not equal to the 2nd wavelength X 2 of λ 1, according to described two incident light wavelengths and polarization state diffraction or transmission selectively, it is characterized in that

Described polarization diffraction device utilizes optical activity material and these two kinds of being connected to form diffraction grating of optical material of optical isotropy material and forms,

By using described optical activity material to become with a kind of materials processing in the described optical isotropy material after section configuration has the concavo-convex grating of periodicity, at least at the described optical activity material of recess filling of the described grating of this processing and the another kind of material in the described optical isotropy material and form described diffraction grating

Described polarization diffraction device has the reflected waveband that reflection is selected in the circular polarization of bringing, and this reflected waveband at the incident light of described the 1st circularly polarized light, is not contained in described the 1st wavelength X 1 and described the 2nd wavelength X 2 in the object of reflection wavelength at least.

3. polarization diffraction device according to claim 2 is characterized in that,

Have in the described incident light of described the 1st wavelength X 1 and described the 2nd wavelength X 2, described incident light as described the 1st wavelength X 1 of described reflected waveband transmission peak wavelength nearby, compare with described the 2nd wavelength X 2, with the optical activity material of the rotatory dispersion function with more relatively discovery, the 1st circularly polarized incident light that makes described the 1st wavelength X 1 wavelength polarization of diffraction is selectively selected the diffraction function.

4. polarization diffraction device according to claim 2, it is characterized in that, in the incident light of two described different wave lengths, a wavelength is in the shortwave side shorter than described reflected waveband, a wavelength is in the long wave side than described reflection wave segment length, employing makes the 1st circularly polarized light and the 2nd circularly polarized light diffraction or the transmission of the incident light of a wavelength selectively in shortwave side and the optical activity material that the long wave side than described reflection wave segment length has different rotatory dispersion functions shorter than described reflected waveband.

5. polarization diffraction device according to claim 3 is characterized in that having:

Use described optical activity material to become section configuration to have the grating of periodically concavo-convex raster shape with a kind of materials processing in the optical isotropy material, described optical activity material wavelength X the refractive index of described the 1st circularly polarized light and difference to the refractive index of described the 2nd circularly polarized light are designated as Δ n (λ) time, satisfy Δ n (λ 1)＞Δ n (λ 2), and Δ n (λ 2) ≈ 0, this optical isotropy material the refractive index of described the 2nd wavelength X 2 and described optical activity material about equally and

At least at the described optical activity material of recess filling of the described grating of this processing and the compaction material of the another kind of material in the described optical isotropy material.

6. polarization diffraction device according to claim 5, it is characterized in that, described optical activity material is made of cholesterol phase liquid crystal, the helical axis directions of described cholesterol phase liquid crystal is consistent with thickness direction, simultaneously to described the 1st circularly polarized light, described cholesterol phase liquid crystal has not described the 1st wavelength X 1 and described the 2nd wavelength X 2 is contained in described reflected waveband in the object of reflection wavelength, and the pitch that described cholesterol phase liquid crystal is had makes described the 1st wavelength X 1 for to compare the transmission peak wavelength of more close described reflected waveband relatively with described the 2nd wavelength X 2.

7. polarization diffraction device according to claim 5, it is characterized in that, described optical activity material is made of the polymer-stabilized cholesterol blue phase liquid crystal that utilizes macromolecule network to enlarge the temperature range of the blue phase of cholesterol, to described the 1st circularly polarized light, described polymer-stabilized cholesterol blue phase liquid crystal has not described the 1st wavelength X 1 and described the 2nd wavelength X 2 is contained in described reflected waveband in the object of reflection wavelength, and the wavelength selectivity that described polymer-stabilized cholesterol blue phase liquid crystal had simultaneously makes described the 1st wavelength X 1 for compare the transmission peak wavelength of relative more close described reflected waveband with described the 2nd wavelength X 2.

8. polarization diffraction device according to claim 4 is characterized in that,

Comprise

Suppose wavelength X be Δ n (λ) with respect to the refractive index of described the 1st circularly polarized light with respect to the difference of the refractive index of described the 2nd circularly polarized light the time,

For one wavelength in the different incident light of two wavelength,

The described optical activity material of Δ n (λ) ≈ 0 and

For at least one circularly polarized light of described the 1st circularly polarized light and described the 2nd circularly polarized light, the refractive index of refractive index and described optical activity material described optical isotropy material about equally.

9. polarization diffraction device according to claim 8, it is characterized in that, described optical activity material is made of cholesterol phase liquid crystal, the helical axis directions of described cholesterol phase liquid crystal is consistent with thickness direction, simultaneously to described the 1st circularly polarized light, whole wavelength that described cholesterol phase liquid crystal has not an incident light that two wavelength is different are contained in the described reflected waveband in the object of reflection wavelength, and the pitch that described cholesterol phase liquid crystal is had makes that reflected waveband is in the different incident light of described two wavelength, grow up than the shortest incident wave, reflected waveband than the ejected wave length of growing into most.

10. optic probe device,

Possess

At least two semiconductor lasers of the light that emission at least two bundle wavelength are different,

The light that this semiconductor laser is launched be concentrated on object lens on the optical recording media,

With the beam splitter of the optical diffraction of at least one wavelength in the light of described optical recording media reflection and

Detect the photodetector of light of the described wavelength of described diffraction,

Carry out the record and/or the playback of described optical recording media,

It is characterized in that described beam splitter comprises each the described polarization diffraction device in claim 3～claim 9,

Described beam splitter is the hologram beam splitter that hologram pattern that the angle of the spacing of grating grid and grating grid distributes in grating formation face constitutes.

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