CN100479043C - Optical pick-up apparatus and divergent angle-converting element - Google Patents

Abstract

An optical pickup device having interchangeability among a high-density optical disk, a DVD and a CD and satisfying both light quantity ensuring and spherical aberration correction at the same time, and a divergent angle conversion element. The optical pickup device comprises a first divergent angle conversion element through which a first light flux with wavelength lambda1 passes, and a second divergent angle conversion element through which a second light flux with wavelength lambda2 and a third light flux with wavelength lambda3 pass, characterized in that an optical magnification m2 between the second divergent angle conversion element and the second light flux and an optical magnification m3 between the second divergent angle conversion element and the third light flux are different from each other.

Description

Light pick-up device and divergent angle-converting element

Technical field

The present invention relates to light pick-up device and divergent angle-converting element.

Background technology

In recent years, carrying out adding the research and development of the so-called high density compact disc of large storage capacity by using the recording density of the blue laser raising optical information recording media (CD) about wavelength 400nm.

Standard as high density compact disc; for example; it is known that to make the picture number formulary value aperture (NA) of object lens be about 0.85; protective substrate thickness is the CD of about 0.1mm; perhaps, NA and protective substrate thickness are suppressed to about 0.65 and the about CD of 0.6mm with existing DVD (digital universal disc) equal extent.In the following description; is NA about 0.85; protective substrate thickness is that the high density compact disc about 0.1mm is designated as " BD (Blu-ray dish) ", is NA about 0.65, and protective substrate thickness is that the high density compact disc about 0.6mm is designated as " AOD (Advanced Optical Disc) ".AOD is also referred to as " HD-DVD (High Density-DVD) " sometimes.

And, various light pick-up devices with interchangeability of this high density compact disc and DVD or CD current widely used CDs such as (compact disc) have been proposed.

In addition, wavelength X 1/ λ 2/ λ 3 of the light beam that uses in AOD/DVD/CD is respectively the about 780nm of the about 650nm/ of about 400nm/, and protective substrate thickness t 1/t2/t3 is respectively the about 1.2mm of the about 0.6mm/ of about 0.6mm/.

In addition, wavelength X 1/ λ 2/ λ 3 of the light beam that uses in BD/DVD/CD is respectively the about 780nm of the about 650nm/ of about 400nm/, and protective substrate thickness t 1/t2/t3 is respectively the about 1.2mm of the about 0.6mm/ of about 0.1mm/.

In order to reach the exchange between the multiple like this CD; the light quantity that need guarantee the light beam that uses in each CD is disclosed; revise simultaneously and result from the difference of wavelength or protective substrate thickness and the aberration that produces, the technology of diffraction structure is set on the optical surface of the optical element that constitutes light pick-up device.

For example, opening invention disclosed in the flat 8-249707 communique the spy is the light pick-up device that DVD/CD exchanges usefulness, and the holographic collimator of the tight front by being configured in object lens uses diffraction light to carry out the regeneration etc. of DVD, and the use non-diffracted light is carried out the regeneration of CD etc.

In addition, also has the situation of using the optical unit that two light sources of outgoing light beams of different wavelengths are packaged together for the miniaturization of seeking light pick-up device, in this case, known to make the incident angle difference of two kinds of light beams, the technology of configuration coupling object lens or collimation lens to object lens.

For example, opening invention disclosed in the 2001-236680 communique the spy has been to use the DVD/CD of above-mentioned optical unit to exchange the light pick-up device of usefulness, by diffraction structure is set in coupled lens, revises and result from the wavelength difference of two kinds of light beams and the aberration of the coupling object lens self that take place.

Yet, open in the flat 8-249707 communique in the invention disclosed the spy, owing to use non-diffracted light to carry out the regeneration etc. of CD, therefore compare with the situation of having utilized diffraction light, can not say to have sufficient aberration debugging functions.

And in order in high density compact disc/DVD/CD, to reach exchange; the aberration that not only needs to revise the above-mentioned difference that results from wavelength or protective substrate thickness like that and take place; also need to revise result from the light beam that in high density compact disc, uses wavelength variation and the aberration that takes place is difficult to guarantee sufficient aberration correction performance in the disclosed technology in above-mentioned patent documentation.

Specifically,, known no matter object lens are refractor or diffraction lens, all needed to make object lens different for the optical magnification of DVD and CD in order to exchange for three CDs.Yet, in order to ensure light quantity, have at the optical magnification that makes ten light device integral body and be under the situation of predetermined value or use under the situation of the light source cell that is called 2LD1P of market sale, from picking up the relation in light device space, when in DVD and CD, wishing freely to set distance from the collimator of DVD and CD to light source etc., must with the location independent ground of light source in object lens according to the optic angle incident light that matches with its optical magnification.Thereby in DVD and CD under the common situation of using collimator or coupled lens, the optical magnification of wishing a collimator or coupled lens is according to wavelength and difference.

Summary of the invention

Problem of the present invention has been considered above problem, provide have high density compact disc, the interchangeability of DVD and CD, not only guaranteed light quantity but also revised light pick-up device and the divergent angle-converting element of aberration.

Above-mentioned problem can reach by following structure.

The light pick-up device of the 1st structure of the present invention has: outgoing wavelength X 1 (the 1st light beam of 380nm≤λ 1≤450nm), the 1st light source that uses for the 1st optical information recording media for the protective substrate that has thickness t 1mm on information recording surface carries out the regeneration of information and/or record; (the 2nd light beam of 650nm≤λ 2≤700nm) is for (the 2nd optical information recording media of the 2nd protective substrate of t1≤t2) carries out the regeneration of information and/or record and the 2nd light source that uses for have thickness t 2mm on information recording surface for outgoing wavelength X 2; (the 3rd light beam of 750nm≤λ 3≤800nm) is for (the 3rd optical information recording media of the protective substrate of t2≤t3) carries out the regeneration of information and/or record and the 3rd light source that uses for have thickness t 3mm on information recording surface for outgoing wavelength X 3; At least pass through the 1st divergent angle-converting element of above-mentioned the 1st light beam; At least pass through the 2nd divergent angle-converting element of above-mentioned the 2nd light beam and the 3rd light beam; And the object optical element that passes through above-mentioned the 1st light beam, the 2nd light beam and the 3rd light beam.The feature of above-mentioned light pick-up device is: the optical magnification m2 for above-mentioned the 2nd light beam of above-mentioned the 2nd divergent angle-converting element is different mutually with the optical magnification m3 for above-mentioned the 3rd light beam of above-mentioned the 2nd divergent angle-converting element.

According to the present invention, owing to can therefore can reach the exchange of wavelength X 2 and λ 3 according to light being incided in the object lens with the corresponding angle of the imaging magnification of object lens.

As the 2nd structure of the present invention; it is the divergent angle-converting element that in light pick-up device, uses; wherein; this light pick-up device is according to wavelength X 1 (the 1st light beam of 380nm≤λ 1≤450nm) from the 1st light source outgoing; carry out the regeneration and/or the record of information for the 1st optical information recording media of the 1st protective substrate that on information recording surface, has thickness t 1mm; according to wavelength X 2 (the 2nd light beam of 600nm≤λ 2≤700nm) from the 2nd light source outgoing; (the 2nd optical information recording media of the 2nd protective substrate of t1≤t2) carries out the regeneration and/or the record of information for have thickness t 2mm on information recording surface; according to (the 3rd light beam of 750nm≤λ 3≤800nm), (the 3rd optical information recording media of the 3rd protective substrate of t2≤t3) carries out the regeneration and/or the record of information for have thickness t 3mm on information recording surface from the wavelength X 3 of the 3rd light source outgoing.

The feature of above-mentioned divergent angle-converting element is: when above-mentioned the 2nd light beam and above-mentioned the 3rd light beam had passed through above-mentioned divergent angle-converting element, the optical magnification m2 for above-mentioned the 2nd light beam of above-mentioned divergent angle-converting element was different mutually with the optical magnification m3 for above-mentioned the 3rd light beam of above-mentioned divergent angle-converting element.

In addition, feature is: on from the luminous point of above-mentioned the 2nd light source to the optical axis of the information recording surface of above-mentioned the 2nd optical information recording media apart from T2 (mm) with from the luminous point of above-mentioned the 3rd light source to the optical axis of the information recording surface of above-mentioned the 3rd optical information recording media on satisfy apart from T3 (mm)

T2+0.6＝T3

Relation.

If according to the present invention, then owing to can therefore can reach the exchange of wavelength X 2 and λ 3 according to light being incided in the object lens with the corresponding angle of the imaging magnification of object lens.And then, can be in DVD and CD shared optical system from the light source to object lens.

Description of drawings

Fig. 1 is the skeleton diagram of structure of an example of expression light pick-up device.

Fig. 2 is the sectional view of the structure major part of expression object optical element.

Fig. 3 is the sectional view of the structure major part of expression object optical element.

Fig. 4 is the sectional view of major part of an example of expression folded form diffraction structure.

Embodiment

In this manual, so-called " aberration " refer in light wavelength changed+during 1nm, with the direction of leaving object optical element situation, with the unit representation of μ m/nm for the variation (μ m) of just having represented the corrugated aberration minimum position relevant with the optical axis direction of focal point on the optical information recording media.

In addition, so-called " aberration of～element self " refers under situation about estimating with this element monomer, changed in light wavelength+during 1nm, with the direction of leaving object optical element situation for the variation of just having represented the corrugated aberration minimum position relevant with the optical axis direction of its focal point.

In addition, so-called " numerical aperture of image planes side " refers to the numerical aperture (beam diameter conversion NA) that the spot diameter of the focal point from the information recording surface that is formed on optical information recording media converses.

In addition, even under the situation of using the optical element that constitutes by general optical materials such as plastics or glass, because the dispersivity of optical material, the optical magnification of this optical element also changes according to wavelength change, and in the present invention, so-called " divergent angle-converting element is different mutually for the optical magnification m2 and the m3 of the light beam of wavelength X 2 and wavelength X 3 " refer to by on divergent angle-converting element, the structure that diffraction structure etc. for example has wavelength dependency (wavelength selectivity) is set, with above-mentioned like that be that the variation of the optical magnification of cause is compared with the chromatic dispersion, the variation (difference) of bigger optical magnification takes place.

In the light pick-up device as the 1st structure of the present invention, it is desirable to above-mentioned the 1st divergent angle-converting element is collimation lens.

And then, the satisfying on it is desirable to from the luminous point of above-mentioned the 2nd light source to the optical axis of the information recording surface of above-mentioned the 2nd optical information recording media apart from T2 (mm) and information recording surface from the luminous point of above-mentioned the 3rd light source to above-mentioned the 3rd optical information recording media apart from T3 (mm)

T2+0.6＝T3

Relation.

According to the present invention, owing to the shortest NA maximum of wavelength, therefore in the big high density compact disc of error aberration generating capacity, by adopting structure to object lens incident directional light, therefore be easy to carry out the adjustment of light pick-up device, also can suppress the aberration generating capacity even error takes place.In addition, if T2+0.6=T3, then owing to make the distance from the divergent angle-converting element to the light source equate, the compactness of therefore using the 2LD1P of market sale just can seek light pick-up device.

In addition, in light pick-up device of the present invention, it is desirable to t1=t2.

According to the present invention because the difference of t1, t2, t3 is little, be 0 if therefore make the optical magnification of object lens for the light of wavelength X 1, then for the optical magnification of other light also near 0.Because the light that incides object lens approaches unlimited directional light, even so session when following the tracks of such object lens depart from for the vertical direction of optical axis, the deterioration of aberration is also very little.

In light pick-up device of the present invention, it is desirable to satisfy-1/50≤m2≤1/50, the relation of 1/10≤m3≤1/4.

According to the present invention,, therefore can carry out the record and the regeneration of the 2nd optical information recording media and the 3rd optical information recording media because the light of wavelength X 2 and λ 3 incides in the object lens with suitable angle.

In addition, in light pick-up device of the present invention, it is desirable at least one optical surface of above-mentioned the 2nd divergent angle-converting element, the 1st diffraction structure is set.

According to the present invention,, therefore be to be applicable to like this to make the different angle of divergence of optical magnification change the structure of element according to wavelength because diffraction structure can depend on wavelength diffraction is provided.

Better is that above-mentioned the 1st diffraction structure is made of zigzag diffraction endless belt.

According to the present invention, the 1st diffraction structure is the structure that improves the diffraction efficiency of specific diffraction number of times as credit light type diffraction structure, is very suitable as the structure that forms on the optical element of the needed light of light quantity of record by CD and regeneration.

In addition, if be formed on each jump between the above-mentioned diffraction endless belt in above-mentioned the 1st diffraction structure in the optical axis direction projection length be designated as d1, then better is satisfied

0.9×λ2/(n2-1)≤d1＜1.5×λ3/(n3-1)

Relation.

In the formula, the refractive index for the light of wavelength X 2 of the material that constitutes above-mentioned the 2nd divergent angle-converting element is designated as n2; The refractive index for the light of wavelength X 3 of the material that constitutes above-mentioned the 2nd divergent angle-converting element is designated as n3.

And then, better is carries out regeneration and/or record for the information of above-mentioned the 2nd optical information recording media by a diffraction light that is subjected to above-mentioned the 2nd light beam that diffraction produces from above-mentioned the 1st diffraction structure, carries out regeneration and/or record for the information of above-mentioned the 3rd optical information recording media by a diffraction light that is subjected to above-mentioned the 3rd light beam that diffraction produces from above-mentioned the 1st diffraction structure.

According to the present invention, can improve diffraction efficiency for the both sides of the light of wavelength X 2 and λ 3.

In addition, above-mentioned the 1st diffraction structure is to be that to be listed in the overlapping type diffraction structure that inside formed a plurality of endless belt of terrace structure also be desirable form to central row with the optical axis.

According to the present invention, in the light of wavelength X 2 and λ 3, can make an optical diffraction and remaining light passes through, diffraction can optionally be provided.

In addition, it is desirable to each jump in the above-mentioned terrace structure in the optical axis direction projection length d 1 satisfy following relation.

0.9×λ2/(n2-1)≤d1＜1.5×λ3/(n3-1)

In the formula, the refractive index for the light of wavelength X 2 of the material that constitutes above-mentioned the 2nd divergent angle-converting element is designated as n2, the material of above-mentioned the 2nd divergent angle-converting element of formation is designated as n3 for the refractive index of the light of wavelength X 3.

In addition, light pick-up device of the present invention it is desirable to when the use of above-mentioned light pick-up device, the aberration that is formed on the aberration of the 1st focal point on the information recording surface of above-mentioned the 1st optical information recording media by above-mentioned the 1st light beam and is formed on the 2nd focal point on the information recording surface of above-mentioned the 2nd optical information recording media by above-mentioned the 2nd light beam all be suppressed in information regeneration and/or write down in the necessary scope.

According to the present invention, high for the wavelength X 1 of defocus amount corrugated aberration rapid deterioration, the light of λ 2, even can realize the optical system that wavelength variation also can not defocus for lack NA because of wavelength.In common laser instrument, have the phenomenon be called mode hopping, from low-power when high power switches, oscillation wavelength moment changes, but gearing does not catch up with.Even also can correctly write down and regenerate under these circumstances, by revising aberration.

Better is, by the absolute value of the aberration of above-mentioned the 1st focal point is suppressed is smaller or equal to 0.15 μ m/nm, the absolute value of the aberration of above-mentioned the 2nd focal point is suppressed for smaller or equal to 0.2 μ m/nm, above-mentioned aberration is suppressed at recording of information and/or writes down in the necessary scope.

According to the present invention, the wavelength variation amount during for the mode hopping that produces in general laser instrument can normally write down and regenerate even defocus also.

In addition, in light pick-up device of the present invention, it is desirable in the optical surface of above-mentioned the 2nd divergent angle-converting element, the 2nd diffraction structure is set on the optical surface that above-mentioned the 1st diffraction structure is not set.

According to the present invention,, increase degree of freedom by being provided with than two diffraction structures more than 1.The light that the 2nd divergent angle-converting element plays for wavelength X 2 and λ 3 becomes predetermined optical magnification, provides colour correction effect totally two effects for the light of wavelength 2.For this reason, need two diffraction structures.

In addition, in such structure, better is, under the situation that above-mentioned the 1st diffraction structure is made of zigzag diffraction endless belt, be formed on each jump between the above-mentioned diffraction endless belt in above-mentioned the 1st diffraction structure in the optical axis direction projection length d 1 satisfy following relational expression, at above-mentioned the 1st diffraction structure is to be that the center has been arranged in inside and formed under the situation of folded form diffraction structure of a plurality of endless belt of a plurality of terrace structures with the optical axis, for each jump in the above-mentioned terrace structure in the optical axis direction projection length d 1 satisfy following relational expression.

0.9×λ2/(n2-1)≤d1＜1.5×λ3/(n3-1)

And, better is, under the situation that above-mentioned the 2nd diffraction structure is made of zigzag diffraction endless belt, be formed on each jump between the above-mentioned diffraction endless belt in above-mentioned the 2nd diffraction structure in the optical axis direction projection length d 2 satisfy at least one of following relational expression, at above-mentioned the 2nd diffraction structure is to be that the center has been arranged in inside and formed under the situation of folded form diffraction structure of a plurality of endless belt of a plurality of terrace structures with the optical axis, each jump in the above-mentioned terrace structure in the optical axis direction projection length d 2 satisfy at least one of following relational expression.

1.4×λ2/(n2-1)≤d2＜1.8×λ2/(n2-1)

0.9×λ2/(n2-1)≤d2＜1.1×λ2/(n2-1)

0.9×λ3/(n3-1)≤d2＜1.1×λ3/(n3-1)

In the formula, the refractive index for the light of wavelength X 2 of the material that constitutes above-mentioned the 2nd divergent angle-converting element is designated as n2, the material of above-mentioned the 2nd divergent angle-converting element of formation is designated as n3 for the refractive index of the light of wavelength X 3.

In addition, it is desirable to above-mentioned d2 especially satisfies

0.9×λ2/(n2-1)≤d2＜1.1×λ2/(n2-1)

Relation.

And then, it is desirable to above-mentioned the 2nd divergent angle-converting element when the wavelength conversion of incident beam arrives long wavelength's one side, come outgoing with wavelength variations to the also big emergence angle of emergence angle before long wavelength's one side than above-mentioned incident beam.

According to the present invention, owing to compare with wavelength X 2, λ 3 incides in the object lens with the big angle of divergence, therefore revises the spherical aberration of wavelength X 2, λ 3 both sides' light.

In light pick-up device of the present invention, above-mentioned the 1st diffraction structure is formed on the optical surface of light source one side of above-mentioned the 2nd divergent angle-converting element, be subjected to a diffraction light of above-mentioned the 2nd light beam of diffraction generation from above-mentioned the 1st diffraction element, produce n22 diffraction light of above-mentioned the 2nd light beam by being subjected to diffraction from above-mentioned the 2nd diffraction structure, use n22 diffraction light of above-mentioned the 2nd light beam to carry out regeneration and/or record for the information of above-mentioned the 2nd optical information recording media, be subjected to a diffraction light of above-mentioned the 3rd light beam of diffraction generation from above-mentioned the 1st diffraction structure, by from the diffraction of above-mentioned the 2nd diffraction structure and produce n23 diffraction light of above-mentioned the 3rd light beam, use n23 diffraction light of above-mentioned the 3rd light beam to carry out regeneration and/or record for the information of above-mentioned the 3rd optical recording media, (n22 n23) satisfies to it is desirable to the combination of said n 22 and said n 23

(n22, n23)=(2,1), in (0,1) and (1,0) any.

According to the present invention, the 2nd divergent angle-converting element becomes predetermined optical magnification for the light of wavelength X 2 and λ 3, provides the colour correction effect for the light of wavelength 2, can play this two kinds of effects.

In the present invention in the light pick-up device of Miao Shuing, it is desirable to satisfy (n22, n23)=(0,1), the absolute value of the aberration that above-mentioned object optical element self has with respect to from the light beam of above-mentioned the 1st light source outgoing for smaller or equal to 0.10 μ m/nm.

According to the present invention, because the light for wavelength X 1 carries out colour correction in object lens, therefore for the residual aberration of the light of wavelength X 2.On the other hand, because a diffraction structure is arranged in the 2nd divergent angle-converting element, therefore the light for wavelength X 2 and λ 3 becomes predetermined optical magnification, and for the residual aberration of the light of wavelength X 2.The aberration of this residual aberration and object lens is left out, at the light correction aberration of optical system integral body for wavelength X 2.

In the light pick-up device of Miao Shuing, better is to form the 3rd diffraction structure at least one optical surface of above-mentioned collimation lens (the 1st divergent angle-converting element) in the present invention.

According to the present invention, in object lens, taken place under the situation of aberration of wavelength X 1, the 3rd diffraction structure of the enough collimation lenses of energy is revised, even under the situation of the colour correction of carrying out himself with object lens, by the colour correction of the instrument self that collimates, also can carry out colour correction in optical system integral body.

The wavelength of better is above-mentioned 1st light beam of above-mentioned collimation lens in inciding above-mentioned collimation lens moves on under the situation of long wavelength's one side the outgoing diverging light from λ 1.

According to the present invention, residual aberration in the enough collimator correction object lens of energy.

In addition, in light pick-up device of the present invention, the value that it is desirable to the aberration that above-mentioned object optical element self has with respect to from the light beam of above-mentioned the 1st light source outgoing in the scope of-0.15 μ m/nm～-0.6 μ m/nm.

It is desirable at least one optical surface in the optical surface of above-mentioned object lens diffraction structure is set.

According to the present invention, in object lens, for the aberration of wavelength X 2, λ 3 both sides' residual object lens of light.On the other hand, because a diffraction structure is arranged on the 2nd divergent angle-converting element, therefore the light for wavelength X 2 and λ 3 becomes predetermined optical magnification, and for the residual aberration of the light of λ 2.The aberration of this residual aberration and object lens is left out, at the light correction aberration of optical system integral body for wavelength X 2.

And then, in light pick-up device of the present invention, it is desirable to be subjected to from above-mentioned object optical element the diffraction light of diffraction generation at above-mentioned the 3rd light beam, the diffraction efficiency E3 with diffraction light of maximum diffraction efficiency satisfies

30％≤E3≤60％

Relation.

According to the present invention, even for λ 1, λ 3 becomes under about 2 times situation, because different diffractions can be provided for both sides' light, therefore can utilize in exchange.

In light pick-up device of the present invention, it is desirable to make above-mentioned the 1st light beam to become directional light and incide in the above-mentioned object optical element.

According to the present invention, because the shortest NA maximum of wavelength, therefore for error, in the big high density compact disc of aberration generating capacity, by adopting the structure of incident directional light in object lens, be easy to carry out the adjustment of light pick-up device, even taking place, error also can suppress the aberration generating capacity.

In light pick-up device of the present invention, it is desirable to the light source cell that above-mentioned the 2nd light source and above-mentioned the 3rd light source are packaged together.

According to the present invention, can seek the compactness of light pick-up device.

In light pick-up device of the present invention, it is plastic it is desirable to above-mentioned object optical element.

According to the present invention, that light pick-up device becomes is in light weight, cost is low.In addition, reduce the burden of gearing, bring power saving thus.

In light pick-up device of the present invention, it is desirable between above-mentioned the 1st light source and above-mentioned collimation lens, to possess beam shaping.

According to the present invention, can there be the light that utilizes lavishly from laser emitting, bring the high life and the power saving of laser instrument thus.

In light pick-up device of the present invention, it is desirable to above-mentioned the 2nd divergent angle-converting element and make above-mentioned the 2nd light beam become parallel light emergence.

According to the present invention, because the short NA of wavelength is big, therefore for error, in the big high density compact disc of aberration generating capacity, by adopting the structure of incident directional light in object lens, the adjustment that is easy to pick up the light device also can suppress the aberration generating capacity even error takes place.

In light pick-up device of the present invention, it is plastic it is desirable to above-mentioned the 2nd divergent angle-converting element.

According to the present invention, that light pick-up device becomes is in light weight, cost is low.

In light pick-up device of the present invention, above-mentioned light pick-up device has makes above-mentioned the 1st light beam, the beam splitter of the light path unanimity of the 2nd light beam and the 3rd light beam, the optical surface of above-mentioned object optical element only is made of plane of refraction, above-mentioned the 1st divergent angle-converting element has when above-mentioned light pick-up device uses, when from the wavelength of the 1st light beam of above-mentioned the 1st light source outgoing when λ 1 has changed, the aberration of the 1st focal point that on above-mentioned the 1st optical information recording media, forms be suppressed at information regeneration and/or write down the 1st diffraction structure in the necessary scope, simultaneously, above-mentioned the 2nd divergent angle-converting element has when making the dispersion angle of above-mentioned the 2nd light beam and the 3rd light beam all little than incidence time, make that the dispersion angle of above-mentioned the 2nd light beam is littler than the dispersion angle of above-mentioned the 3rd light beam, and the 2nd diffraction structure of outgoing.

According to the present invention, object lens are owing to being refractor, therefore for the residual aberration of the light of wavelength X 1.Can revise its aberration effectively by enough the 1st diffraction structures that is formed on the 1st divergent angle-converting element.In addition, for the light of wavelength X 2 and λ 3, owing to can therefore can reach the exchange of wavelength X 2 and λ 3 according to light being incided in the object lens with the corresponding angle of the optical magnification of object lens.

In light pick-up device of the present invention, it is desirable to above-mentioned the 2nd divergent angle-converting element makes above-mentioned the 2nd light beam become parallel light emergence, make above-mentioned the 3rd light beam become the diverging light outgoing, and then it is one of desirable form that above-mentioned the 1st divergent angle-converting element makes above-mentioned the 1st light beam become the outgoing of convergence light.

According to the present invention,, therefore can reach exchange for three wavelength because object lens are refractors.

In addition, compare with the situation that makes the 1st light beam become parallel light emergence, the limited magnification of the 3rd light beam reduces.Thus, the intelligent image that produces in the time of can being reduced in the session tracking is poor.

In light pick-up device of the present invention, it also is desirable form that above-mentioned the 2nd divergent angle-converting element makes above-mentioned the 2nd light beam and the 3rd light beam all become the diverging light outgoing, and then it also is one of desirable form that above-mentioned the 1st divergent angle-converting element makes above-mentioned the 1st light beam become parallel light emergence.

According to the present invention,, can reach exchange for three wavelength because object lens are refractors.Because the shortest NA maximum of wavelength, therefore for error, in the big high density compact disc of aberration generating capacity, by adopting the structure for object lens incident directional light, the adjustment that is easy to pick up the light device also can suppress the aberration generating capacity even error takes place.

In addition, in light pick-up device of the present invention, above-mentioned the 2nd divergent angle-converting element makes above-mentioned the 2nd light beam become the outgoing of convergence light, makes above-mentioned the 3rd light beam become the diverging light outgoing, and then it also is one of desirable form that above-mentioned the 1st divergent angle-converting element makes above-mentioned the 1st light beam become parallel light emergence.

In light pick-up device of the present invention, above-mentioned the 1st protective substrate thickness t 1mm satisfies

0.5≤t1≤0.7

It also is one of desirable form.

According to the present invention because the difference of t1, t2, t3 is little, if therefore make the optical magnification of object lens become 0 for the light of wavelength X 1, then for other the optical magnification of light also near 0.Because the light that incides object lens approaches unlimited directional light,, also reduce the deterioration of aberration even such object lens are along the direction skew vertical with optical axis when therefore session is followed the tracks of.

In addition, in light pick-up device of the present invention, the thickness t 1mm of above-mentioned the 1st protective substrate satisfies

0.08≤t1≤0.12

It also is one of desirable form.

According to the present invention, the difference of t1, t2, t3 is big, and the difference of the optical magnification of object lens is also big, because carrier is thick, therefore for the light of the short wavelength X 3 of the distance of object lens and carrier, its distance can extend.

In light pick-up device of the present invention, it is desirable to above-mentioned light pick-up device and in the light path of above-mentioned the 1st light beam, possess optical beam expander.

According to the present invention, because the shortest NA maximum of wavelength, therefore for error, in the big high density compact disc of aberration generating capacity, the wavelength dispersion that also can revise effectively with the individual difference of temperature variation or laser instrument is the spherical aberration that reason produces.

In above-mentioned divergent angle-converting element, it is desirable to t1=t2 as the present invention's the 2nd structure.

According to the present invention, the light of wavelength X 1 and λ 2 only is the different spherical aberrations that produce of wavelength owing to revising, and therefore according to the diffraction structure of object lens, even carry out the exchange of these two wavelength, also can reduce the chromosphere surface aberration of diffraction.

In above-mentioned conversion divergent angle-converting element of the present invention, it is desirable to satisfy

-1/50≤m2≤1/50

1/10≤m3≤1/4

Relation.

According to the present invention,, therefore can carry out the record and the regeneration of the 2nd optical information recording media and the 3rd optical recording media because the light of wavelength X 2 and λ 3 incides in the object lens with suitable angle.

In above-mentioned divergent angle-converting element of the present invention, it is desirable at least one optical surface of above-mentioned divergent angle-converting element, the 1st diffraction structure is set.

According to the present invention,, therefore be to make structure suitable in the different divergent angle-converting element of optical magnification like this according to wavelength because diffraction structure can rely on wavelength diffraction is provided.

In above-mentioned divergent angle-converting element of the present invention, it is desirable to above-mentioned the 1st diffraction structure and constitute by zigzag diffraction endless belt.

According to the present invention, because the 1st diffraction structure is the structure that improves the diffraction efficiency of specific diffraction number of times the picture credit light type diffraction structure, therefore the structure on the optical element of the conduct needed light of light quantity that is formed on the record by CD and regenerates such suits.

In above-mentioned divergent angle-converting element of the present invention, better is the diffraction light of above-mentioned light pick-up device according to above-mentioned the 2nd light beam that is subjected to the diffraction generation from above-mentioned the 1st diffraction structure, carry out regeneration and/or record for the information of above-mentioned the 2nd optical information recording media, a diffraction light according to above-mentioned the 3rd light beam that is subjected to the diffraction generation from above-mentioned the 1st diffraction structure carries out regeneration and/or record for the information of above-mentioned the 3rd optical information recording media.

According to the present invention, can improve diffraction efficiency for the both sides of the light of wavelength X 2 and λ 3.

In above-mentioned divergent angle-converting element of the present invention, above-mentioned the 1st diffraction structure is to be that the overlapping type diffraction structure that a plurality of endless belt that formed terrace structure in inside have been arranged at the center also is one of desirable form with the optical axis.

According to the present invention, because in the light of wavelength X 2 and λ 3, can light of diffraction and make remaining light transmission, therefore can optionally provide diffraction.

In addition, in above-mentioned divergent angle-converting element of the present invention, better is is not provided with in the optical surface of above-mentioned divergent angle-converting element on the optical surface of above-mentioned the 1st diffraction structure the 2nd diffraction structure is set.

According to the present invention, increase degree of freedom by being provided with than two diffraction structures more than 1.The 2nd divergent angle-converting element becomes predetermined optical magnification for the light of wavelength X 2 and λ 3, provides the colour correction effect for the light of wavelength 2, plays this two kinds of effects.For this reason, two diffraction structures of the highest needs.

In above-mentioned divergent angle-converting element of the present invention, it is desirable to above-mentioned divergent angle-converting element when the wavelength variations of incident beam arrives long wavelength's one side, come outgoing to the also big emergence angle of emergence angle before long wavelength's one side with wavelength variations than above-mentioned incident beam.

According to the present invention, in object lens, compare with wavelength X 2, λ 3 revises the spherical aberration of wavelength X 2, λ 3 both sides' light with big angle of divergence incident.

In above-mentioned divergent angle-converting element of the present invention, above-mentioned the 1st diffraction structure is formed on the optical surface of light source one side of above-mentioned divergent angle-converting element, be subjected to a diffraction light of above-mentioned the 2nd light beam of diffraction generation from above-mentioned the 1st diffraction structure, be subjected to diffraction from above-mentioned the 2nd diffraction structure and produce n22 diffraction light of above-mentioned the 2nd light beam, use n22 diffraction light of above-mentioned the 2nd light beam to carry out regeneration and/or record for the information of above-mentioned the 2nd optical information recording media, be subjected to a diffraction light of above-mentioned the 3rd light beam of diffraction generation from above-mentioned the 1st diffraction structure, be subjected to diffraction from above-mentioned the 2nd diffraction structure and produce n23 diffraction light of above-mentioned the 3rd light beam, use n23 diffraction light of above-mentioned the 3rd light beam to carry out regeneration and/or record for the information of above-mentioned the 3rd optical information recording media, it is desirable to the combination (n22 of said n 22 and n23, n23) satisfy (n22, n23)=(2,1), (0,1) any and in (1,0).

According to the present invention, above-mentioned the 2nd divergent angle-converting element becomes predetermined optical magnification for the light of wavelength X 2 and λ 3, provides the colour correction effect for the light of wavelength X 2, can play this two kinds of effects.

In above-mentioned divergent angle-converting element of the present invention, it is desirable to make above-mentioned the 2nd light beam to become parallel light emergence.

According to the present invention, to compare with the situation that makes the 1st light beam become parallel light emergence, the limited magnification of the 3rd light beam reduces.Therefore, the intelligent image that produces in the time of can being reduced in the session tracking is poor.

In addition, above-mentioned divergent angle-converting element of the present invention is preferably plastic.

If according to the present invention, then light pick-up device become in light weight, cost is low.

Example

Below, with reference to accompanying drawing, explain and be used to implement the 1st example of the present invention.

Fig. 1 roughly represents can both carry out the structure of the 1st light pick-up device PU1 of recording of information/regeneration aptly for AOD (the 1st optical information recording media), DVD (the 2nd optical information recording media) and CD (the 3rd optical information recording media) any.The optical specification of AOD is wavelength X 1=407nm; the thickness t 1=0.6mm of protective seam PL1; numerical aperture NA1=0.65; the optical specification of DVD is wavelength X 2=655nm; the thickness t 2=0.6mm of protective seam PL2; numerical aperture NA2=0.65, the optical specification of CD is wavelength X 3=785nm, the thickness t 3=1.2mm of protective seam PL3, numerical aperture NA3=0.51.But the thickness of wavelength, protective seam and the combination of numerical aperture are not limited to above situation.In addition, as the 1st optical information recording media, also can use the thickness t 1 of protective seam PL1 to be the high density compact disc about 0.1mm.

Light pick-up device PU1 is by the blue violet semiconductor laser LD1 (the 1st light source) of the laser beam (the 1st light beam) of luminous when carrying out recording of information processing regeneration for AOD and outgoing 407nm; The photodetector PD1 that the 1st light beam is used; The red laser diode LD2 (the 2nd light source) of the laser beam (the 2nd light beam) of luminous when carrying out recording of information/regeneration for DVD and outgoing 655nm and the recording of information/regeneration of the light source cell LU23 infrared semiconductor laser LD3 (the 3rd light source) of the laser beam (the 3rd light beam) of luminous and outgoing 785nm is made of one when carrying out to(for) CD; The photodetector PD23 that the 2nd light beam and the 3rd light beam are shared; Only pass through the collimation lens L1 (the 1st divergent angle-converting element) of the 1st light beam; In the time of by the 2nd light beam and the 3rd light beam, on optical surface, formed the 2nd divergent angle-converting element L2 of the 1st diffraction structure; Has object lens (object optical element) OBJ that makes each laser beam function of optically focused on information recording surface RL1, RL2, RL3; The 1st beam splitter BS1; The 2nd beam splitter BS2; The 3rd beam splitter BS3; Diaphragm STO; Formations such as sensing lens SEN1 and SEN2.

In addition, explain narration in the back, also can in the 1st compensating element L1 and object lens OBJ, diffraction structure be set.

In light pick-up device PU1, when carrying out recording of information/regeneration for AOD, as describing its opticpath with solid line among Fig. 1, at first, make blue violet semiconductor laser LD1 luminous, from the divergent beams of blue violet semiconductor laser LD1 outgoing by the 1st beam splitter BS1, see through the 1st divergent angle-converting element L1, become after the parallel beam,, arrive object optical element OBJ by the 2nd beam splitter BS2.

And, by make be subjected to the 1st light beam that diffraction produces from the diffraction structure of object optical element OBJ the diffraction light of pre-determined number through the protective seam PL1 optically focused of AOD to information recording surface RL1, form luminous point (the 1st focal point).The aberration of the 1st focal point be suppressed in information regeneration and or write down in the necessary scope, specifically, the absolute value of the aberration of the 1st focal point is suppressed for smaller or equal to 0.15 μ m/nm.

And object optical element OBJ is focused on by the two shaft drive AC (not shown) that are configured in its periphery or session is followed the tracks of.The folded light beam of having been modulated by information pits at information recording surface RL1 is once more by object optical element OBJ, the 2nd beam splitter BS2, the 1st divergent angle-converting element L1, by the 1st beam splitter BS1 separately, SEN1 provides astigmatism by the sensing lens, converges on the light-sensitive surface of photodetector PD1.And the output signal of use photodetector PD1 can the information of reading and recording in AOD.

In addition, when carrying out recording of information/regeneration for DVD, as describing at first, to make red laser diode LD2 luminous its opticpath with the single-point line among Fig. 1.Pass through the 3rd beam splitter BS3 from the divergent beams of red laser diode LD2 outgoing, when when seeing through the 2nd divergent angle-converting element L2, being transformed to parallel beam, be subjected to diffraction according to the 1st diffraction structure, its diffraction light is reflected by the 2nd beam splitter BS2, arrives object optical element OBJ.

And, by make be subjected to the 2nd light beam that diffraction produces from the diffraction structure of object optical element OBJ the diffraction light of pre-determined number through the protective seam PL2 optically focused of DVD to information recording surface RL2, form luminous point (the 2nd focal point).The aberration of the 2nd focal point be suppressed in information regeneration and or write down in the necessary scope, specifically, the absolute value of the aberration of the 2nd focal point is suppressed for smaller or equal to 0.2 μ m/nm.

And object optical element OBJ is focused on by the two shaft drive AC that are configured in its periphery or session is followed the tracks of.The folded light beam of having been modulated by information pits at information recording surface RL2 by the 3rd beam splitter BS3 separately, converges on the light-sensitive surface of photodetector PD23 once more by object optical element OBJ, the 2nd beam splitter BS2, the 2nd divergent angle-converting element L2.And the output signal of use photodetector PD23 can the information of reading and recording in DVD.

In addition, when carrying out recording of information/regeneration for CD,, at first, make infrared semiconductor laser LD3 luminous as with dashed lines among Fig. 1 has been described its opticpath.Pass through the 3rd beam splitter BS3 from the divergent beams of infrared semiconductor laser LD3 outgoing, when seeing through the 2nd divergent angle-converting element L2, be transformed to parallel beam, simultaneously, be subjected to diffraction according to the 1st diffraction structure, its diffraction light is reflected by the 2nd beam splitter BS2, arrives object optical element OBJ.

And, by make the inferior diffraction light of n3 (n3 is a natural number) that is subjected to the 3rd light beam that diffraction produces from the diffraction structure of object optical element OBJ through the protective seam PL3 optically focused of CD to information recording surface RL3, form luminous point (the 3rd focal point).The aberration of the 3rd focal point is suppressed in the regeneration of information and or writes down in the necessary scope.

And object optical element OBJ is focused on by the two shaft drive AC that are configured in its periphery or session is followed the tracks of.The folded light beam of having been modulated by information pits at information recording surface RL3 by the 3rd beam splitter BS3 separately, converges on the light-sensitive surface of photodetector PD23 once more by object optical element OBJ, the 2nd beam splitter BS2, the 2nd divergent angle-converting element L2.And the output signal of use photodetector PD23 can the information of reading and recording in CD.

Object optical element OBJ is the piece plastic lens with the double-sized non-spherical that makes the function of the 1st～the 3rd beam condenser to the information recording surface RL1～RL3 of CD.In addition, also can constitute object optical element to a plurality of optical elements sets altogether.

On the plane of incidence of object optical element OBJ, form credit light type diffraction structure DOE as shown in Figure 2.Credit light type diffraction structure DOE is for for the light beam from the 1st light source outgoing, revises the aberration that object optical element OBJ self has and is provided with, and specifically, is designed so that the absolute value of aberration becomes smaller or equal to 0.15 μ m/nm.

The 1st divergent angle-converting element L1 has to make from the 1st light source LD1 becomes the alignment function of parallel light emergence as the 1st light beam of diverging light outgoing, simultaneously, credit light type diffraction structure DOE same as shown in Figure 2 is set on its exit facet.This credit light type diffraction structure DOE is for for the light beam from the 1st light source outgoing, revises the aberration that the 1st divergent angle-converting element L1 self has and designs, and specifically, is designed so that the absolute value of aberration becomes smaller or equal to 2.1 μ m/nm.

The 2nd divergent angle-converting element L2 forms credit light type diffraction structure DOE same as shown in Figure 2 as the 1st diffraction structure on its exit facet.And, the 2nd divergent angle-converting element L2 have by the wavelength selectivity that utilizes the 1st diffraction structure to be had make from the 2nd light source LD2 as the 2nd light beam of diverging light outgoing become parallel light emergence alignment function, make from the 3rd light source LD3 and change to the less angle of divergence and the function of outgoing as the angle of divergence of the 3rd light beam of diverging light outgoing, can make the 2nd divergent angle-converting element RL2 become different value mutually with m3 for the optical magnification m2 of the wavelength X 2 and the light beam of wavelength X 3.

In addition, satisfy T2+0.6=T3 apart from T3 (mm) apart from T2 (mm) and on from the luminous point of the 2nd light source LD2 to the optical axis of the information recording surface RL2 of DVD from the luminous point of the 3rd light source LD3 to the optical axis of the information recording surface RL3 of CD.This be because the thickness t 3 of the protective seam PL3 of CD (=1.2mm) than the thickness t 2 of the protective seam PL2 of DVD (=0.6mm) thick 0.6mm.

In addition, can make m2 and m3 in the scope that satisfies-1/50≤m2≤1/50,1/10≤m3≤1/4.

In addition, as the 1st diffraction structure or the object optical element OBJ of the 2nd divergent angle-converting element L2 and be formed on diffraction structure on the 1st divergent angle-converting element L1, for example, can be as shown in Figure 4 be the overlapping type diffraction structure HOE of the center structure of having arranged a plurality of endless belt R that formed terrace structure in inside with the optical axis.

If structure and the method for designing of general overlapping type diffraction structure HOE are described, then the depth d 0 on each rank of the terrace structure that forms in each endless belt R is set at the value that calculates according to d0=k * λ 1/ (n1-1) (μ m), and several N of cutting apart of each endless belt R are set at 5.Wherein, λ 1 is the wavelength from blue violet semiconductor laser emitting laser light beam (here, λ 1=0.408 μ m) with the micron unit representation, and n1 is the 1st divergent angle-converting element L1 for the refractive index of wavelength X 1 (here, n1=1.5242).

For this overlapping type diffraction structure HOE incident under the situation of laser beam of wavelength X 1, the optical path difference of k * λ 1 (μ m) takes place between the ladder of adjacency, in fact the laser beam of wavelength X 1 owing to do not provide phase differential, therefore diffraction and directly seeing through not.In addition, in the following description, the light beam that does not provide phase differential in fact according to overlapping type diffraction structure and directly see through is called diffraction light 0 time.

For example, when k=2, for this overlapping type diffraction structure HOE incident from the wavelength X 2 of red laser diode outgoing (here, 2=0.658 under the situation of laser beam μ m), between the ladder of adjacency, produce the optical path difference of d0 * (n2-1)-λ 2=0.13 μ m, in by the part of the 5 endless belt R of cutting apart, owing to produce the optical path difference of 0.13 * 5=0.65 μ m and a wavelength degree of wavelength X 2, so stagger a respectively wavelength and overlapping of the corrugated that has seen through the endless belt R of adjacency.That is, according to this overlapping type diffraction structure HOE, the light beam of wavelength X 2 becomes along the diffraction light of first power to diffraction.In addition, n2 is the 2nd divergent angle-converting element L2 for the refractive index of wavelength X 2 (here, n2=1.5064).The diffraction efficiency of a diffraction light of the laser beam of wavelength X 2 at this moment becomes 87.5%, is sufficient light quantity in the recording of information/regeneration for DVD.

In object optical element OBJ, formed under the situation of overlapping type diffraction structure HOE,, can revise the spherical aberration that the difference in thickness by the wavelength of AOD and DVD causes according to the effect of overlapping type diffraction structure HOE.Under the different situation of protective substrate thickness as BD, DVD, can revise the spherical aberration that the difference by wavelength and protective substrate thickness causes.

In addition, for the overlapping type diffraction structure HOE incident of making this structure from the wavelength X 3 of infrared semiconductor laser outgoing (here, under the situation of laser beam λ 3=0.785 μ m), owing to be λ 3 ≈ 2 * λ 1, therefore the optical path difference of 1 * λ 3 (μ m) takes place between the ladder of adjacency, the laser beam of the wavelength X 3 also laser beam with wavelength X 1 is identical, owing in fact do not provide phase differential, and therefore diffraction and directly see through (0 diffraction light) not.

In object optical element OBJ, formed under the situation of overlapping type diffraction structure HOE; in object optical element OBJ; different by making with the magnification of wavelength X 3 for wavelength X 1, can revise the spherical aberration that the difference by the thickness of the protective seam of AOD and CD causes.

In addition, in this example, owing in the 1st divergent angle-converting element L1, only pass through the 1st light beam, therefore do not need to utilize the wavelength selectivity of overlapping type diffraction structure HOE as described above, and for example, under situation about the 1st divergent angle-converting element L1 being configured between the 2nd beam splitter BS2 and the object optical element OBJ, owing to become in the 1st compensating element L1 by the 1st～the 3rd light beam, therefore in this case, can adopt and in the 1st compensating element L1, form overlapping type diffraction structure HOE, utilize the wavelength selectivity of overlapping type diffraction structure HOE, in the 1st compensating element, only provide diffraction, the structure of diffraction is not provided in the 2nd light beam and the 3rd light beam for the 1st light beam.

In addition, above explanation with suppose in overlapping type diffraction structure HOE incident the 1st～the 3rd light beam, the relevant situation of method for designing when making overlapping type diffraction structure HOE have wavelength selectivity for three wavelength of the 1st～the 3rd light beam, according to this method, can make the 1st diffraction structure have wavelength selectivity for two wavelength of the 2nd light beam and the 3rd light beam.

As mentioned above, according to described divergent angle-converting element L2 of this example and light pick-up device PU1, have the 2nd divergent angle-converting element L2 of wavelength selectivity by configuration in the common light path of the 2nd light beam and the 3rd light beam, can be in DVD and CD shared optical system from the light source to object lens.

In addition, by using the light source cell LU23 that the 2nd light source LD2 and the 3rd light source LD3 are made of one, the structure of incident the 2nd light beam and the 3rd light beam in the 2nd divergent angle-converting element L2, thus can in DVD and CD, obtain sufficient light quantity and aberration inhibit feature.

In addition, can in the optical surface of the 2nd diverging light inverting element L2, not be provided with on the optical surface of the 1st diffraction structure yet the 2nd diffraction structure is set.

In this case, if a diffraction light that is subjected to the light beam of the wavelength X 2 that diffraction produces from the 1st diffraction structure uses the inferior diffraction light of n22 (n22 is a natural number) that is subjected to the light beam of the wavelength X 2 that diffraction produces from the 2nd diffraction structure, carry out regeneration and/or record for the information of DVD, a diffraction light that is subjected to the light beam of the wavelength X 3 that diffraction produces from the 1st diffraction structure uses the inferior diffraction light of n23 (n23 is a natural number) that is subjected to the light beam of the wavelength X 3 that diffraction produces from the 2nd diffraction structure, carry out regeneration and/or record for the information of CD, preferably satisfy the combination (n22 of n22 and n23, n23)=(2,1), (0,1) or (1,0).

It is in addition, preferably satisfied that (n22, n23)=(0,1), the absolute value of the aberration that object optical element self has becomes smaller or equal to 0.10 μ m/nm for the light beam from the 1st light source outgoing.

In addition, at least one optical surface of the 1st divergent angle-converting element L1, diffraction structure is set, moves at the wavelength of incident beam under the situation of long wavelength's one side and make the diverging light outgoing.In this case, the value of the aberration that object optical element self has is preferably for the light beam from the 1st light source outgoing, in the scope of-0.5 μ m/nm～-0.6 μ m/nm.

Secondly, with reference to description of drawings and enforcement the 2nd form of the present invention.

The basic structure of the 2nd form since with homomorphosis, therefore use Fig. 1 to describe.

Light pick-up device PU1 is by the blue violet semiconductor laser LD1 (the 1st light source) of the laser beam (the 1st light beam) of luminous when carrying out recording of information processing regeneration for AOD and outgoing 407nm; The photodetector PD1 that the 1st light beam is used; The red laser diode LD2 (the 2nd light source) of the laser beam (the 2nd light beam) of luminous when carrying out recording of information/regeneration for DVD and outgoing 655nm and the recording of information/regeneration of the light source cell LU23 infrared semiconductor laser LD3 (the 3rd light source) of the laser beam (the 3rd light beam) of luminous and outgoing 785nm is made of one when carrying out to(for) CD; The photodetector PD23 that the 2nd light beam and the 3rd light beam are shared; Only pass through the 1st divergent angle-converting element L1 of the 1st light beam; By the 2nd light beam and the 3rd light beam the 2nd divergent angle-converting element L2; Object optical element OBJ with the function that makes each laser beam optically focused on information recording surface RL1, RL2, RL3; The 1st beam splitter BS1; The 2nd beam splitter BS2; The 3rd beam splitter BS3; Diaphragm STO; Formations such as sensing lens SEN1 and SEN2.

In addition, detailed explanation is narrated in the back, at the 1st diffraction structure of the aberration that is formed with the 1st focal point on the information recording surface RL1 of AOD that the wavelength variation that is used to revise with the 1st light beam is a cause on the optical surface of the 1st divergent angle-converting element L1, on the optical surface of the 2nd divergent angle-converting element L2, be formed with the 2nd diffraction structure of the dispersion angle that makes the 2nd light beam and the 3rd light beam all makes the 2nd light beam in little than incidence time dispersion angle and outgoing littler than the dispersion angle of the 3rd light beam.In addition, on the optical surface of object optical element OBJ, do not form diffraction structure, constitute optical surface with plane of refraction.

In light pick-up device PU1, when carrying out recording of information/regeneration for AOD, as describing its opticpath with solid line among Fig. 1, at first, make blue violet semiconductor laser LD1 luminous, pass through the 1st beam splitter BS1 from the divergent beams of blue violet semiconductor laser LD1 outgoing, arrive the 1st divergent angle-converting element L1.

And when seeing through the 1st beam splitter BS1, the diffraction light change that is subjected to the pre-determined number of the 1st light beam that diffraction produces from the 1st diffraction structure is changed to parallel beam, by the 2nd beam splitter BS2, arrives object optical element OBJ.

And, provide refraction action by the plane of refraction of object optical element OBJ, by make the 1st light beam through the protective seam PL1 optically focused of AOD to information recording surface RL1, form luminous point (the 1st focal point).

And object optical element OBJ is focused on by the two shaft drive AC (not shown) that are configured in its periphery or session is followed the tracks of.The folded light beam of having been modulated by information pits at information recording surface RL1 is once more by object optical element OBJ, the 2nd beam splitter BS2, the 1st divergent angle-converting element L1, by the 1st beam splitter BS1 separately, SEN1 provides astigmatism by the sensing lens, converges on the light-sensitive surface of photodetector PD1.And the output signal of use photodetector PD1 can the information of reading and recording in AOD.

Here; designing the 1st diffraction structure makes when carrying out recording of information/regeneration for AOD; for example; even in the wavelength variations of following blue violet semiconductor laser LD1; the thickness error of protective seam PL1; jumping Jiao between the information recording surface of dual layer discs; under the influence of the variations in refractive index of the object optical element OBJ of the heating of variation of ambient temperature or two shaft drive AC2 etc. etc.; the spherical aberration of the 1st focal point on the information recording surface RL1 is along revising superfluous direction or revise not enough direction when having changed, and also can be suppressed at the regeneration of information to the aberration of the 1st focal point on the information recording surface RL1 and or writes down in the necessary scope.Specifically, designing the 1st diffraction structure makes the absolute value of aberration of the 1st focal point become smaller or equal to 0.15 μ m/nm.

In addition, when carrying out recording of information/regeneration for DVD, as describing at first, to make red laser diode LD2 luminous its opticpath with the single-point line among Fig. 1.Pass through the 3rd beam splitter BS3 from the divergent beams of red laser diode LD2 outgoing, arrive the 2nd divergent angle-converting element L2.

And when seeing through the 2nd divergent angle-converting element L2, the diffraction light change that is subjected to the pre-determined number of the 2nd light beam that diffraction produces from the 2nd diffraction structure is changed to parallel beam, by the 2nd beam splitter BS2 reflection, arrives object optical element OBJ.

And, provide refraction action by the plane of refraction of object optical element OBJ, by make the 2nd light beam through the protective seam PL2 optically focused of DVD to information recording surface RL2, form luminous point (the 2nd focal point).

And object optical element OBJ is focused on by the two shaft drive AC that are configured in its periphery or session is followed the tracks of.The folded light beam of having been modulated by information pits at information recording surface RL2 by the 3rd beam splitter BS3 separately, converges on the light-sensitive surface of photodetector PD23 once more by object optical element OBJ, the 2nd beam splitter BS2, the 2nd divergent angle-converting element L2.And the output signal of use photodetector PD23 can the information of reading and recording in DVD.

Usually, object optical element OBJ has been an optimization for AOD, therefore for object optical element OBJ incident under the situation of the 2nd light beam, the 2nd luminous point on the information recording surface RL2 of DVD changes along revising superfluous direction at the lower peripheral surface aberration that influences of the wavelength dispersion of object optical element OBJ.Therefore, in this example, when carrying out recording of information/regeneration for DVD, design the 2nd diffraction structure and make that revising this spherical aberration changes.Specifically, designing the 2nd diffraction structure makes the absolute value of aberration of the 2nd focal point become smaller or equal to 0.25 μ m/nm.

In addition, when carrying out recording of information/regeneration for CD,, at first, make infrared semiconductor laser LD3 luminous as with dashed lines among Fig. 1 has been described its opticpath.Pass through the 3rd beam splitter BS3 from the divergent beams of infrared semiconductor laser LD3 outgoing, arrive the 2nd divergent angle-converting element L2.

And when seeing through the 2nd divergent angle-converting element L2, the diffraction light that is subjected to the pre-determined number of the 3rd light beam that diffraction produces from the 2nd diffraction structure is transformed to the dispersion angle littler than the dispersion angle of incidence time, from the 2nd divergent angle-converting element L2 outgoing.Wherein, littler from the dispersion angle of the 2nd light beam of the 2nd divergent angle-converting element L2 outgoing than dispersion angle from the 3rd light beam of the 2nd divergent angle-converting element L2 outgoing.

Reflect by the 2nd beam splitter BS2 as the 3rd light beam of diverging light outgoing from the 2nd divergent angle-converting element L2, arrive object optical element OBJ.

And, provide refraction action by the plane of refraction of object optical element OBJ, by make the 3rd light beam through the protective seam PL3 optically focused of CD to information recording surface RL3, form luminous point (the 3rd focal point).The aberration of the 3rd focal point is suppressed in the regeneration of information and or writes down in the necessary scope.

And object optical element OBJ is focused on by the two shaft drive AC that are configured in its periphery or session is followed the tracks of.The folded light beam of having been modulated by information pits at information recording surface RL3 by the 3rd beam splitter BS3 separately, converges on the light-sensitive surface of photodetector PD23 once more by object optical element OBJ, the 2nd beam splitter BS2, the 2nd divergent angle-converting element L2.And the output signal of use photodetector PD23 can the information of reading and recording in CD.

Usually; object optical element OBJ has been an optimization for AOD; therefore for object optical element OBJ incident during the 3rd light beam; the 3rd focal point on the information recording surface RL3 of CD is under the influence of the difference in thickness of the protective seam PL3 of the protective seam PL1 of the influence of the wavelength dispersion of object optical element OBJ, AOD and CD, and spherical aberration changes along revising superfluous direction.Therefore, in this example, design the 2nd diffraction structure and make when carrying out recording of information/regeneration for CD, revise this spherical aberration and change.

As the 1st diffraction structure and the 2nd diffraction structure, for example can enumerate credit light type diffraction structure DOE as shown in Figure 3, perhaps as shown in Figure 4 be the overlapping type diffraction structure HOE of the center structure of having arranged a plurality of endless belt R that formed terrace structure in inside with the optical axis.

About overlapping type diffraction structure HOE manufacture and design and method for designing identical with the 1st above-mentioned example.

As mentioned above, in the light pick-up device PU shown in this example, by using the 1st diffraction structure only to provide diffraction for the 1st light beam, use the 2nd diffraction structure to provide diffraction for the 2nd light beam and the 3rd light beam, even the structure of diffraction structure is not set in object optical element OBJ, the exchange light pick-up device that also can obtain guaranteeing sufficient light quantity He have the high density compact disc/DVD/CD of aberration correction performance.

In addition, by using the light source cell LU23 that the 2nd light source LD2 and the 3rd light source LD3 are packaged together, can be in the optical element of the optical system that constitutes light pick-up device PU shared the 2nd light beam and the 3rd light beam, can realize the miniaturization of light pick-up device PU or reduce number of components.

In addition, in this example, the 2nd divergent angle-converting element L2 makes the light beam of wavelength X 2 become parallel light emergence, make the light beam of wavelength X 3 become the diverging light outgoing, but be not limited to this situation, also can be that the 2nd divergent angle-converting element L2 makes the light beam of wavelength X 2 and λ 3 become the structure of diverging light outgoing, perhaps make the light beam of wavelength X 2 become the outgoing of convergence light, make the light beam of wavelength X 3 become the structure of diverging light outgoing.

In addition, can also be that the 1st divergent angle-converting element L1 makes the structure of the light beam of wavelength X 1 as the outgoing of convergence light.

Embodiment

[embodiment 1]

Secondly, the 1st embodiment of light pick-up device, the 1st divergent angle-converting element and the 2nd divergent angle-converting element represented in above-mentioned example is described.

The lens data of each light-emitting component of expression in table 1, the table 2.

[table 1]

[table 2]

Aspherical surface data

The 1st compensating element

The 3rd

Asphericity coefficient

κ-6.6436×E+1

The 4th (HD-DVD:1 the photochemical wavelength 1mm of credit)

Asphericity coefficient κ-8.3465 * E-1

The optical path difference function

C2-6.2961×E-0

C4-1.5298×E-2

Divergent angle-converting element

The 3rd (the DVD:2 time CD:1 time photochemical wavelength 1mm of credit)

Asphericity coefficient

κ-1.0000×E+3

The optical path difference function

C2-2.4248×E+0

C4+6.2330×E-4

The 4th (the DVD:1 time CD:1 time photochemical wavelength 1mm of credit)

Asphericity coefficient:

κ-4.7604×E-1

The optical path difference function

C2+2.0944×E+1

C4+1.2308×E-1

Object lens

The 6th (AOD:3 time DVD:2 time CD:2 time (HD-DVD:1 the photochemical wavelength 1mm of credit)

Asphericity coefficient

κ-4.4715×E-1

A2-7.2396×E-4

A4-1.3187×E-3

A6+5.4370×E-4

A8-1.0983×E-4

A10+8.5286×E-6

A12-1.3509×E-6

The optical path difference function

C2-8.1308×E-0

C4-4.6175×E-1

C6-2.8616×E-1

C8+6.6346×E-2

C10-7.9277×E-3

The 7th

Asphericity coefficient

κ-4.1355×E+2

A2-9.4311×E-3

A4+1.1572×E-2

A6-5.3553×E-3

A8+1.2651×E-3

A10-1.5851×E-4

A12+8.2843×E-6

As shown in table 1, focal distance f 1=3.1mm when the object lens of present embodiment are set at wavelength X 1=407nm, picture number formulary value aperture NA1=0.65, focal distance f 2=3.19mm when being set at wavelength X 2=655nm, picture number formulary value aperture NA2=0.65, focal distance f 3=3.16mm when being set at wavelength X 3=785nm is as number formulary value aperture NA3=0.51.

In addition, in the present embodiment, in the plane of incidence (the 6th face) of the plane of incidence (the 3rd face) of the exit facet (the 4th face) of the 1st divergent angle-converting element, the 2nd divergent angle-converting element and exit facet (the 4th face), object optical element (object lens), form credit light type diffraction structure.

In addition, the magnification m1, the m2 that become for the 1st light beam and the 2nd light beam almost are 0, making the 1st light beam and the 2nd light beam become directional light and incide in the object lens, is negative for the magnification m3 of the 3rd light beam, makes the 3rd light beam become diverging light and incides structure in the object lens.

On the plane of incidence (the 6th face) and exit facet (the 7th face) of the plane of incidence (the 3rd face) of the plane of incidence (the 3rd face) of the 1st divergent angle-converting element and exit facet (the 4th face), the 2nd divergent angle-converting element and exit facet (the 4th face), object optical element (object lens), formed respectively with substitution in the formula (several 1) below table 1 and table 2 expression coefficient the mathematical formulae regulation, around optical axis L axisymmetric aspheric surface.

[several 1]

The aspherical shape formula

$X\left(h\right)=\frac{(h^2/R)}{1+\sqrt{1-(1+\mathrm{\κ}){(h/R)}^2}}+\underset{i=0}{\overset{9}{\mathrm{\Σ}}}+A_{2i}{h}^{2i}$

Here, X (h) is the axle (with the direct of travel of light for just) of optical axis direction, and κ is the circular cone coefficient, and A2i is the aspheric surface coefficient.

In addition, the interval of the diffraction endless belt mathematical formulae regulation of coefficient of table 2 expression that has been used in substitution in several 2 the optical path difference function.

[several 2]

The optical path difference function

$\mathrm{\Φ}\left(h\right)=\left(\underset{i=0}{\overset{5}{\mathrm{\Σ}}}{B}_{2i}{h}^{2i}\right)\×n\×\mathrm{\λ}/\mathrm{\λB}$

Here, B2i is the coefficient of optical path difference function, and λ is to use wavelength, and λ B is the photochemical wavelength of the credit of diffraction (λ B=1mm).

[embodiment 2]

Secondly, the 2nd embodiment of light pick-up device, the 1st divergent angle-converting element and the 2nd divergent angle-converting element represented in above-mentioned example is described.

Present embodiment is relevant with light pick-up device, this light pick-up device is as above-mentioned the 1st example, all be almost 0 by making for the aberration of the object optical element self of the 1st light beam and the aberration of the 1st divergent angle-converting element self, thereby the aberration of the 1st focal point when light pick-up device is used be suppressed at information regeneration and or write down in the necessary scope, in addition, cancel out each other by making, thereby the aberration of the 2nd focal point when light pick-up device used is suppressed at the regeneration of information and or writes down in the necessary scope for the positive aberration of the object optical element self of the 2nd light beam and the negative aberration of the 2nd divergent angle-converting element self.

The lens data of each optical element of expression in table 3, the table 4.

[table 3]

[table 4]

Aspherical surface data

The 1st compensating element

The 3rd

Asphericity coefficient

κ-2.9816×E+0

The 4th (HD-DVD:1 the photochemical wavelength 1mm of credit)

Asphericity coefficient

κ-6.6298×E-1

A2+6.8060×E-4

A4+4.2157×E-7

The optical path difference function

C2+1.6853×E+1

C4+9.7909×E-1

Divergent angle-converting element

The 3rd

Asphericity coefficient

κ-6.6225×E-0

The 4th (the DVD:1 time CD:1 time photochemical wavelength 1mm of credit)

Asphericity coefficient

κ-8.8682×E-1

The optical path difference function

C2+3.4941×E+1

C4+2.0110×E-2

Object lens

The 6th (the AOD:3 time DVD:2 time CD:2 time photochemical wavelength 1mm of credit)

Asphericity coefficient

κ-4.3741×E-1

A2+1.1713×E-4

A4-1.2104×E-3

A6+5.3927×E-4

A8-1.1589×E-4

A10+1.1395×E-5

A12-1.3946×E-6

The optical path difference function

C2-1.7589×E+1

C4-6.7834×E-1

C6-2.1641×E-1

C8+3.2057×E-2

C10-3.4960×E-3

The 7th

Asphericity coefficient

κ-1.1243×E+3

A2-7.9648×E-3

A4+1.1269×E-2

A6-5.3948×E-3

A8+1.2875×E-3

A10-1.6243×E-4

A12+8.5641×E-6

As shown in table 3, focal distance f 1=3.1mm when the object lens of present embodiment are set at wavelength X 1=407nm, picture number formulary value aperture NA1=0.65, focal distance f 2=3.16mm when being set at wavelength X 2=655nm, picture number formulary value aperture NA2=0.65, focal distance f 3=3.09mm when being set at wavelength X 3=785nm is as number formulary value aperture NA3=0.51.

In addition, in the present embodiment, in the plane of incidence (the 6th face) of the exit facet (the 4th face) of the exit facet (the 4th face) of the 1st divergent angle-converting element, the 2nd divergent angle-converting element, object optical element (object lens), form credit light type diffraction structure.

In addition, the magnification m1, the m2 that become for the 1st light beam and the 2nd light beam almost are that 0, the 1 light beam and the 2nd light beam incide in the object lens as directional light, are negative for the magnification m3 of the 3rd light beam, and the 3rd light beam incides structure in the object lens as diverging light.

On the plane of incidence (the 6th face) and exit facet (the 7th face) of the plane of incidence (the 3rd face) of the plane of incidence (the 3rd face) of the 1st divergent angle-converting element and exit facet (the 4th face), the 2nd divergent angle-converting element and exit facet (the 4th face), object optical element (object lens), form respectively the table 3 that has been used in substitution in above-mentioned several 1 and table 4 expression coefficient the mathematical formulae regulation, around optical axis L axisymmetric aspheric surface.

In addition, the interval of the diffraction endless belt mathematical formulae regulation of coefficient of table 4 expression that has been used in substitution in above-mentioned several 2 the optical path difference function.

[embodiment 3]

Secondly, the 3rd embodiment of light pick-up device, the 1st divergent angle-converting element and the 2nd divergent angle-converting element represented in above-mentioned example is described.

Present embodiment is relevant with light pick-up device, this light pick-up device is as above-mentioned the 2nd example, all be almost 0 by making for the aberration of the object optical element self of the 2nd light beam and the aberration of the 2nd divergent angle-converting element self, thereby the aberration of the 2nd focal point when light pick-up device is used be suppressed at information regeneration and or write down in the necessary scope, in addition, cancel out each other by making, thereby the aberration of the 1st focal point when light pick-up device used is suppressed at the regeneration of information and or writes down in the necessary scope for the negative aberration of the object optical element self of the 1st light beam and the positive aberration of the 1st divergent angle-converting element self.

The lens data of each optical element of expression in table 5, the table 6.

[table 5]

[table 6]

Aspherical surface data

The 1st compensating element

The 3rd

Asphericity coefficient

κ-1.2865×E-1

The 4th (HD-DVD:1 the photochemical wavelength 1mm of credit).

Asphericity coefficient

κ-5.8016×E-0

A2-1.2220×-4

A4-8.2772×E-7

The optical path difference function

C2-3.4973×E+1

C4-3.1167×E-1

Divergent angle-converting element

The 3rd

Asphericity coefficient

κ+5.0000×E-0

The 4th (the DVD:2 time CD:1 time photochemical wavelength 1mm of credit)

Asphericity coefficient

κ-3.0879×E-1

The optical path difference function

C2-6.6329×E-0

C4-9.6488×E-4

Object lens

The 6th (the AOD:3 time DVD:2 time CD:2 time photochemical wavelength 1mm of credit)

Asphericity coefficient

κ-4.6387×E-1

A2-1.8195×E-4

A4-1.8297×E-3

A6+7.6730×E-4

A8-1.4668×E-4

A10+4.2269×E-6

A12-3.3788×E-7

The optical path difference function

C2 0

C4-4.3190×E-1

C6-2.3777×E-1

C8+7.3114×E-2

C10-1.0422×E-2

The 7th asphericity coefficient

κ-2.8743×E+2

A2-8.7882×E-3

A4+1.1311×E-2

A6-5.3137×E-3

A8+1.2888×E-3

A10-1.6378×E-4

A12+8.6619×E-6

As shown in table 5, focal distance f 1=3.1mm when the object lens of present embodiment are set at wavelength X 1=407nm, picture number formulary value aperture NA1=0.65, focal distance f 2=3.21mm when being set at wavelength X 2=655nm, picture number formulary value aperture NA2=0.65, focal distance f 3=3.23mm when being set at wavelength X 3=785nm is as number formulary value aperture NA3=0.51.

In addition, in the present embodiment, in the plane of incidence (the 6th face) of the exit facet (the 4th face) of the exit facet (the 4th face) of the 1st divergent angle-converting element, the 2nd divergent angle-converting element, object optical element (object lens), form credit light type diffraction structure.

In addition, the magnification m1, the m2 that become for the 1st light beam and the 2nd light beam almost are that 0, the 1 light beam and the 2nd light beam incide in the object lens as directional light, are negative for the magnification m3 of the 3rd light beam, and the 3rd light beam incides structure in the object lens as diverging light.

On the plane of incidence (the 6th face) and exit facet (the 7th face) of the plane of incidence (the 3rd face) of the plane of incidence (the 3rd face) of the 1st divergent angle-converting element and exit facet (the 4th face), the 2nd divergent angle-converting element and exit facet (the 4th face), object optical element (object lens), form the axisymmetric aspheric surface around optical axis L of mathematical formulae regulation of the coefficient of the table 5 that has been used in substitution in above-mentioned several 1 and table 6 expression respectively.

In addition, the interval of the diffraction endless belt mathematical formulae regulation of coefficient of table 6 expression that has been used in substitution in above-mentioned several 2 the optical path difference function.

In the table 7, among the expression embodiment 1～3, the aberration (being designated as AOD) when object lens and the 1st divergent angle-converting element are combined, the aberration (being designated as DVD) when object lens and the 2nd divergent angle-converting element are combined.

[table 7]

Aberration [μ m/nm] when object lens and the 1st compensating element or angle of divergence compensating element are combined

	AOD	DVD
			Embodiment 1	0.04	-0.02
Embodiment 2	0.04	-0.01
			Embodiment 3	-0.01	-0.19

As known from Table 7, in each embodiment,, aberration is suppressed in the scope that does not have obstacle in the practicality for AOD and DVD.

Utilizability on the industry

According to the present invention, can access the interchangeability with AOD, DVD and CD, not only guarantee light quantity but also revised light pick-up device and the divergent angle-converting element of aberration.

Claims (62)

1. light pick-up device, this light pick-up device has:

The 1st light beam of outgoing wavelength X 1 is used for carrying out the regeneration of information and/or the 1st light source of record for the 1st optical information recording media of the 1st protective substrate that has thickness t 1mm on information recording surface, wherein, and 380nm≤λ 1≤450nm;

The 2nd light beam of outgoing wavelength X 2 is used for carrying out the regeneration of information and/or the 2nd light source of record for the 2nd optical information recording media of the 2nd protective substrate that has thickness t 2mm on information recording surface, wherein, and 600nm≤λ 2≤700nm, t1≤t2;

The 3rd light beam of outgoing wavelength X 3 is used for carrying out the regeneration of information and/or the 3rd light source of record for the 3rd optical information recording media of the 3rd protective substrate that has thickness t 3mm on information recording surface, wherein, and 750nm≤λ 3≤800nm, t2≤t3;

The 1st divergent angle-converting element that above-mentioned the 1st light beam is passed through;

The 2nd divergent angle-converting element that above-mentioned the 2nd light beam and the 3rd light beam are passed through; And

By the object optical element of above-mentioned the 1st light beam, the 2nd light beam and the 3rd light beam,

It is characterized in that,

The optical magnification m2 for above-mentioned the 2nd light beam of above-mentioned the 2nd divergent angle-converting element is different mutually with the optical magnification m3 for above-mentioned the 3rd light beam of above-mentioned the 2nd divergent angle-converting element.

2. light pick-up device according to claim 1 is characterized in that,

Above-mentioned the 1st divergent angle-converting element is a collimation lens.

3. light pick-up device according to claim 2 is characterized in that,

Satisfying and on from the luminous point of above-mentioned the 2nd light source to the optical axis of the information recording surface of above-mentioned the 2nd optical information recording media from the luminous point of above-mentioned the 3rd light source to the optical axis of the information recording surface of above-mentioned the 3rd optical information recording media apart from T2mm apart from T3mm

T2+0.6＝T3

Relation.

4. light pick-up device according to claim 1 is characterized in that,

t1＝t2。

5. light pick-up device according to claim 1 is characterized in that,

Satisfy

-1/50≤m2≤1/50

1/10≤m3≤1/4

Relation.

6. light pick-up device according to claim 1 is characterized in that,

On at least one optical surface of above-mentioned the 2nd divergent angle-converting element, the 1st diffraction structure is set.

7. light pick-up device according to claim 6 is characterized in that,

Above-mentioned the 1st diffraction structure is made of zigzag a plurality of diffraction endless belt.

8. light pick-up device according to claim 7 is characterized in that,

Be formed on each jump between the above-mentioned diffraction endless belt in above-mentioned the 1st diffraction structure in the optical axis direction projection length d 1 satisfy following relation

0.9×λ2/(n2-1)≤d1＜1.5×λ3/(n3-1)，

In the formula, the refractive index for the light of wavelength X 2 of the material that constitutes above-mentioned the 2nd divergent angle-converting element is designated as n2; The refractive index for the light of wavelength X 3 of the material that constitutes above-mentioned the 2nd divergent angle-converting element is designated as n3.

9. light pick-up device according to claim 7 is characterized in that,

A diffraction light of above-mentioned the 2nd light beam that produces by being subjected to diffraction from above-mentioned the 1st diffraction structure carries out regeneration and/or the record for the information of above-mentioned the 2nd optical information recording media, and a diffraction light of above-mentioned the 3rd light beam that produces by being subjected to diffraction from above-mentioned the 1st diffraction structure carries out regeneration and/or the record for the information of above-mentioned the 3rd optical information recording media.

10. light pick-up device according to claim 6 is characterized in that,

Above-mentioned the 1st diffraction structure is to be the overlapping type diffraction structure that a plurality of endless belt that formed a plurality of terrace structures in inside have been arranged at the center with the optical axis.

11. light pick-up device according to claim 10 is characterized in that,

Each jump in the above-mentioned terrace structure in the optical axis direction projection length d 1 satisfy following relation

0.9×λ2/(n2-1)≤d1＜1.5×λ3/(n3-1)，

In the formula, the refractive index for the light of wavelength X 2 of the material that constitutes above-mentioned the 2nd divergent angle-converting element is designated as n2; The refractive index for the light of wavelength X 3 of the material that constitutes above-mentioned the 2nd divergent angle-converting element is designated as n3.

12. light pick-up device according to claim 6 is characterized in that,

When stating light pick-up device in the use, the absolute value that is formed on the aberration of the 1st focal point on the information recording surface of above-mentioned the 1st optical information recording media by above-mentioned the 1st light beam is suppressed to smaller or equal to 0.15 μ m/nm, and the absolute value that is formed on the aberration of the 2nd focal point on the information recording surface of above-mentioned the 2nd optical information recording media by above-mentioned the 2nd light beam is suppressed to smaller or equal to 0.2 μ m/nm.

13. light pick-up device according to claim 6 is characterized in that,

On the optical surface that above-mentioned the 1st diffraction structure is not set in the optical surface of above-mentioned the 2nd divergent angle-converting element the 2nd diffraction structure is set.

14. light pick-up device according to claim 13 is characterized in that,

When above-mentioned the 2nd divergent angle-converting element arrives long wavelength's one side in the wavelength variations of incident beam, come outgoing to the also big emergence angle of emergence angle before long wavelength's one side with wavelength variations than above-mentioned incident beam.

15. light pick-up device according to claim 13 is characterized in that,

Above-mentioned the 1st diffraction structure is made of zigzag diffraction endless belt, be formed on each jump between the above-mentioned diffraction endless belt in above-mentioned the 1st diffraction structure in the optical axis direction projection length d 1 satisfy following relational expression

0.9×λ2/(n2-1)≤d1＜1.5×λ3/(n3-1)，

Above-mentioned the 2nd diffraction structure is made of zigzag diffraction endless belt, be formed on each jump between the above-mentioned diffraction endless belt in above-mentioned the 2nd diffraction structure in the optical axis direction projection length d 2 satisfy in the following relational expression at least one:

1.4×λ2/(n2-1)≤d2＜1.8×λ2/(n2-1)

0.9×λ2/(n2-1)≤d2＜1.1×λ2/(n2-1)

0.9×λ3/(n3-1)≤d2＜1.1×λ3/(n3-1)

In the formula, the refractive index for the light of wavelength X 2 of the material that constitutes above-mentioned the 2nd divergent angle-converting element is designated as n2; The refractive index for the light of wavelength X 3 of the material that constitutes above-mentioned the 2nd divergent angle-converting element is designated as n3.

16. light pick-up device according to claim 15 is characterized in that,

Be formed on each jump between the above-mentioned diffraction endless belt in above-mentioned the 2nd diffraction structure in the optical axis direction projection length d 2 satisfy following relational expression

0.9×λ2/(n2-1)≤d2＜1.1×λ2/(n2-1)。

17. light pick-up device according to claim 13 is characterized in that,

Above-mentioned the 1st diffraction structure is to be the overlapping type diffraction structure that a plurality of endless belt that formed a plurality of terrace structures in inside have been arranged at the center with the optical axis, each jump in the above-mentioned terrace structure in the optical axis direction projection length d 1 satisfy following relational expression

0.9×λ2/(n2-1)≤d1＜1.5×λ3/(n3-1)，

Above-mentioned the 2nd diffraction structure is to be the overlapping type diffraction structure that a plurality of endless belt that formed a plurality of terrace structures in inside have been arranged at the center with the optical axis, each jump in the above-mentioned terrace structure in the optical axis direction projection length d 2 satisfy in the following relational expression at least one:

1.4×λ2/(n2-1)≤d2＜1.8×λ2/(n2-1)

0.9×λ2/(n2-1)≤d2＜1.1×λ2/(n2-1)

0.9×λ3/(n3-1)≤d2＜1.1×λ3/(n3-1)

In the formula, the refractive index for the light of wavelength X 2 of the material that constitutes above-mentioned the 2nd divergent angle-converting element is designated as n2; The refractive index for the light of wavelength X 3 of the material that constitutes above-mentioned the 2nd divergent angle-converting element is designated as n3.

18. light pick-up device according to claim 17 is characterized in that,

Each jump in the above-mentioned terrace structure in the optical axis direction projection length d 2 satisfy following relational expression

0.9×λ2/(n2-1)≤d2＜1.1×λ2/(n2-1)。

19. light pick-up device according to claim 14 is characterized in that,

Above-mentioned the 1st diffraction structure is formed on the optical surface of light source one side of above-mentioned the 2nd divergent angle-converting element,

Be subjected to diffraction and a diffraction light of above-mentioned the 2nd light beam that produces from above-mentioned the 1st diffraction element, be subjected to diffraction from above-mentioned the 2nd diffraction structure and produce n22 diffraction light of above-mentioned the 2nd light beam, use 22 diffraction lights of said n of above-mentioned the 2nd light beam to carry out regeneration and/or record for the information of above-mentioned the 2nd optical information recording media

Be subjected to diffraction and a diffraction light of above-mentioned the 3rd light beam that produces from above-mentioned the 1st diffraction structure, be subjected to diffraction from above-mentioned the 2nd diffraction structure and produce n23 diffraction light of above-mentioned the 3rd light beam, use n23 diffraction light of above-mentioned the 3rd light beam to carry out regeneration and/or record, wherein for the information of above-mentioned the 3rd optical information recording media

(n22 n23) satisfies in the combination of said n 22 and said n 23

(n22, n23)=(2,1), in (0,1) and (1,0) any.

20. light pick-up device according to claim 19 is characterized in that,

Satisfy (n22, n23)=(0,1),

The absolute value of the aberration that above-mentioned object optical element self has is smaller or equal to 0.10 μ m/nm with respect to the light beam from above-mentioned the 1st light source outgoing.

21. light pick-up device according to claim 12 is characterized in that,

On at least one optical surface of above-mentioned collimation lens, form the 3rd diffraction structure.

22. light pick-up device according to claim 21 is characterized in that,

The wavelength of above-mentioned 1st light beam of above-mentioned collimation lens in inciding above-mentioned collimation lens moves on to from λ 1 under the situation of long wavelength's one side, the outgoing diverging light.

23. light pick-up device according to claim 22 is characterized in that,

The value of the aberration that above-mentioned object optical element self has with respect to from the light beam of above-mentioned the 1st light source outgoing in the scope of-0.15 μ m/nm～-0.6 μ m/nm.

24. light pick-up device according to claim 5 is characterized in that,

On at least one optical surface in the optical surface of above-mentioned object optical element diffraction structure is set.

25. light pick-up device according to claim 24 is characterized in that,

Be subjected to diffraction from above-mentioned object optical element and the diffraction light that produces, the diffraction efficiency E3 with diffraction light of maximum diffraction efficiency satisfies at above-mentioned the 3rd light beam

30％≤E3≤60％

Relation.

26. light pick-up device according to claim 2 is characterized in that,

Above-mentioned the 1st light beam incides in the above-mentioned object optical element as directional light.

27. light pick-up device according to claim 3 is characterized in that,

Above-mentioned the 2nd light source and above-mentioned the 3rd light source are the light source cells that has encapsulated.

28. light pick-up device according to claim 1 is characterized in that,

Above-mentioned object optical element is plastic.

29. light pick-up device according to claim 2 is characterized in that,

Between above-mentioned the 1st light source and above-mentioned collimation lens, possesses beam shaping.

30. light pick-up device according to claim 1 is characterized in that,

Above-mentioned the 2nd divergent angle-converting element is as above-mentioned the 2nd light beam of parallel light emergence.

31. light pick-up device according to claim 1 is characterized in that,

Above-mentioned the 2nd divergent angle-converting element is plastic.

32. light pick-up device according to claim 1 is characterized in that,

Above-mentioned light pick-up device has the beam splitter of the light path unanimity that makes above-mentioned the 1st light beam, the 2nd light beam and the 3rd light beam,

The optical surface of above-mentioned object optical element only is made of plane of refraction,

Above-mentioned the 1st divergent angle-converting element has the 1st diffraction structure, when the 1st diffraction structure is stated light pick-up device in the use, when from the wavelength of the 1st light beam of above-mentioned the 1st light source outgoing when λ 1 has changed, the aberration of the 1st focal point that on above-mentioned the 1st optical information recording media, forms be suppressed at information regeneration and/or write down in the necessary scope

Above-mentioned the 2nd divergent angle-converting element has the 2nd diffraction structure, and the 2nd diffraction structure makes the dispersion angle of above-mentioned the 2nd light beam and the 3rd light beam make the dispersion angle of above-mentioned the 2nd light beam than the little and outgoing of dispersion angle of above-mentioned the 3rd light beam in the time of all little than incidence time.

33. light pick-up device according to claim 32 is characterized in that,

Above-mentioned the 2nd light source and above-mentioned the 3rd light source are the light source cells that has encapsulated.

34. light pick-up device according to claim 32 is characterized in that,

By the absolute value of the aberration of the 1st focal point that is formed on above-mentioned the 1st optical information recording media by above-mentioned the 1st light beam being suppressed for smaller or equal to 0.15 μ m/nm, thereby above-mentioned aberration is suppressed at for the regeneration of the information of above-mentioned the 1st optical information recording media and/or writes down in the necessary scope.

35. light pick-up device according to claim 32 is characterized in that,

By the absolute value of the aberration of the 2nd focal point that is formed on above-mentioned the 2nd optical information recording media by above-mentioned the 2nd light beam being suppressed for smaller or equal to 0.2 μ m/nm, thereby above-mentioned aberration is suppressed at for the regeneration of the information of above-mentioned the 2nd optical information recording media and/or writes down in the necessary scope.

36. light pick-up device according to claim 32 is characterized in that,

Above-mentioned the 2nd divergent angle-converting element above-mentioned the 2nd light beam as parallel light emergence, above-mentioned the 3rd light beam as the diverging light outgoing.

37. light pick-up device according to claim 36 is characterized in that,

Above-mentioned the 1st divergent angle-converting element above-mentioned the 1st light beam as directional light or convergence light outgoing.

38. light pick-up device according to claim 32 is characterized in that,

Above-mentioned the 2nd divergent angle-converting element above-mentioned the 2nd light beam and the 3rd light beam all as the diverging light outgoing.

39. according to the described light pick-up device of claim 38, it is characterized in that,

Above-mentioned the 1st divergent angle-converting element above-mentioned the 1st light beam as parallel light emergence.

40. light pick-up device according to claim 32 is characterized in that,

Above-mentioned the 2nd divergent angle-converting element above-mentioned the 2nd light beam as convergence light outgoing, above-mentioned the 3rd light beam as the diverging light outgoing.

41. according to the described light pick-up device of claim 40, it is characterized in that,

Above-mentioned the 1st divergent angle-converting element above-mentioned the 1st light beam as parallel light emergence.

42. light pick-up device according to claim 32 is characterized in that,

The thickness t 1mm of above-mentioned the 1st protective substrate satisfies

0.5≤t1≤0.7

Relation.

43. light pick-up device according to claim 32 is characterized in that,

The thickness t 1mm of above-mentioned the 1st protective substrate satisfies

0.08≤t1≤0.12

Relation.

44. according to the described light pick-up device of claim 43, it is characterized in that,

Above-mentioned light pick-up device possesses optical beam expander in the light path of above-mentioned the 1st light beam.

45. divergent angle-converting element; this divergent angle-converting element uses in light pick-up device; this light pick-up device is by from the 1st light beam of the wavelength X 1 of the 1st light source outgoing and carry out the regeneration and/or the record of information for the 1st optical information recording media of the 1st protective substrate that has thickness t 1mm at information recording surface; by from the 2nd light beam of the wavelength X 2 of the 2nd light source outgoing and carry out the regeneration and/or the record of information for the 2nd optical information recording media of the 2nd protective substrate that has thickness t 2mm at information recording surface; by from the 3rd light beam of the wavelength X 3 of the 3rd light source outgoing and carry out the regeneration and/or the record of information for the 3rd optical information recording media of the 3rd protective substrate that has thickness t 3mm at information recording surface; wherein; 380nm≤λ 1≤450nm; 600nm≤λ 2≤700nm; t1≤t2; 750nm≤λ 3≤800nm; t2≤t3; it is characterized in that

When above-mentioned the 2nd light beam and above-mentioned the 3rd light beam have passed through above-mentioned divergent angle-converting element, above-mentioned divergent angle-converting element is different mutually for the optical magnification m3 of above-mentioned the 3rd light beam with above-mentioned divergent angle-converting element for the optical magnification m2 of above-mentioned the 2nd light beam

On from the luminous point of above-mentioned the 2nd light source to the optical axis of the information recording surface of above-mentioned the 2nd optical information recording media apart from T2mm with from the luminous point of above-mentioned the 3rd light source to the optical axis of the information recording surface of above-mentioned the 3rd optical information recording media on satisfy apart from T3mm

T2+0.6＝T3

Relation.

46. according to the described divergent angle-converting element of claim 45, it is characterized in that,

t1＝t2。

47. according to the described divergent angle-converting element of claim 45, it is characterized in that,

Satisfy

-1/50≤m2≤1/50

1/10≤m3≤1/4

Relation.

48. according to the described divergent angle-converting element of claim 45, it is characterized in that,

On at least one optical surface of above-mentioned divergent angle-converting element, the 1st diffraction structure is set.

49. according to the described divergent angle-converting element of claim 48, it is characterized in that,

Above-mentioned the 1st diffraction structure is made of zigzag diffraction endless belt.

50. according to the described divergent angle-converting element of claim 49, it is characterized in that,

Be formed on each jump between the above-mentioned diffraction endless belt in above-mentioned the 1st diffraction structure in the optical axis direction projection length d 1 satisfy following relational expression

0.9×λ2/(n2-1)≤d1＜1.5×λ3/(n3-1)，

In the formula, the refractive index for the light of wavelength X 2 of the material that constitutes above-mentioned divergent angle-converting element is designated as n2; The refractive index for the light of wavelength X 3 of the material that constitutes above-mentioned divergent angle-converting element is designated as n3.

51. according to the described divergent angle-converting element of claim 49, it is characterized in that,

Above-mentioned light pick-up device utilization is subjected to diffraction and a diffraction light of above-mentioned the 2nd light beam that produces from above-mentioned the 1st diffraction structure, carry out regeneration and/or record for the information of above-mentioned the 2nd optical information recording media, utilization is subjected to diffraction and a diffraction light of above-mentioned the 3rd light beam that produces carries out regeneration and/or record for the information of above-mentioned the 3rd optical information recording media from above-mentioned the 1st diffraction structure.

52. according to the described divergent angle-converting element of claim 48, it is characterized in that,

Above-mentioned the 1st diffraction structure is to be the overlapping type diffraction structure that a plurality of endless belt that formed terrace structure in inside have been arranged at the center with the optical axis.

53. according to the described divergent angle-converting element of claim 52, it is characterized in that,

Each jump in the above-mentioned terrace structure in the optical axis direction projection length d 1 satisfy following relational expression

0.9×λ2/(n2-1)≤d1＜1.5×λ3/(n3-1)，

In the formula, the refractive index for the light of wavelength X 2 of the material that constitutes above-mentioned divergent angle-converting element is designated as n2; The refractive index for the light of wavelength X 3 of the material that constitutes above-mentioned divergent angle-converting element is designated as n3.

54. according to the described divergent angle-converting element of claim 48, it is characterized in that,

On the optical surface that above-mentioned the 1st diffraction structure is not set in the optical surface of above-mentioned divergent angle-converting element the 2nd diffraction structure is set.

55. according to the described divergent angle-converting element of claim 54, it is characterized in that,

Above-mentioned the 1st diffraction structure is made of zigzag a plurality of diffraction endless belt, be formed on each jump between the above-mentioned diffraction endless belt in above-mentioned the 1st diffraction structure in the optical axis direction projection length d 1 satisfy following relational expression

0.9×λ2/(n2-1)≤d1＜1.5×λ3/(n3-1)，

Above-mentioned the 2nd diffraction structure is made of zigzag a plurality of diffraction endless belt, be formed on each jump between the above-mentioned diffraction endless belt in above-mentioned the 2nd diffraction structure in the optical axis direction projection length d 2 satisfy in the following relational expression at least one:

1.4×λ2/(n2-1)≤d2＜1.8×λ2/(n2-1)

0.9×λ2/(n2-1)≤d2＜1.1×λ2/(n2-1)

0.9×λ3/(n3-1)≤d2＜1.1×λ3/(n3-1)

In the formula, the refractive index for the light of wavelength X 2 of the material that constitutes above-mentioned divergent angle-converting element is designated as n2; The refractive index for the light of wavelength X 3 of the material that constitutes above-mentioned divergent angle-converting element is designated as n3.

56. according to the described divergent angle-converting element of claim 55, it is characterized in that,

Be formed on each jump between the above-mentioned diffraction endless belt in above-mentioned the 2nd diffraction structure in the optical axis direction projection length d 2 satisfy following relational expression

0.9×λ2/(n2-1)≤d2＜1.1×λ2/(n2-1)。

57. according to the described divergent angle-converting element of claim 54, it is characterized in that,

Above-mentioned the 1st diffraction structure is to be the overlapping type diffraction structure that a plurality of endless belt that formed a plurality of terrace structures in inside have been arranged at the center with the optical axis, each jump in the above-mentioned terrace structure in the optical axis direction projection length d 1 satisfy following relational expression

0.9×λ2/(n2-1)≤d1＜1.5×λ3/(n3-1)，

Above-mentioned the 2nd diffraction structure is to be the overlapping type diffraction structure that a plurality of endless belt that formed a plurality of terrace structures in inside have been arranged at the center with the optical axis, each jump in the above-mentioned terrace structure in the optical axis direction projection length d 2 satisfy in the following relational expression at least one:

1.4×λ2/(n2-1)≤d2＜1.8×λ2/(n2-1)

0.9×λ2/(n2-1)≤d2＜1.1×λ2/(n2-1)

0.9×λ3/(n3-1)≤d2＜1.1×λ3/(n3-1)

In the formula, the refractive index for the light of wavelength X 2 of the material that constitutes above-mentioned divergent angle-converting element is designated as n2; The refractive index for the light of wavelength X 3 of the material that constitutes above-mentioned divergent angle-converting element is designated as n3.

58. according to the described divergent angle-converting element of claim 57, it is characterized in that,

Each jump in the above-mentioned terrace structure in the optical axis direction projection length d 2 satisfy following relational expression

0.9×λ2/(n2-1)≤d2＜1.1×λ2/(n2-1)。

59. according to the described divergent angle-converting element of claim 54, it is characterized in that,

When above-mentioned divergent angle-converting element arrives long wavelength's one side in the wavelength variations of incident beam, come outgoing to the also big emergence angle of emergence angle before long wavelength's one side with wavelength variations than above-mentioned incident beam.

60. according to the described divergent angle-converting element of claim 59, it is characterized in that,

Above-mentioned the 1st diffraction structure is formed on the optical surface of light source one side of above-mentioned divergent angle-converting element,

Be subjected to diffraction and a diffraction light of above-mentioned the 2nd light beam that produces from above-mentioned the 1st diffraction structure, be subjected to diffraction from above-mentioned the 2nd diffraction structure and produce n22 diffraction light of above-mentioned the 2nd light beam, use n22 diffraction light of above-mentioned the 2nd light beam to carry out regeneration and/or record for the information of above-mentioned the 2nd optical information recording media

Be subjected to diffraction and a diffraction light of above-mentioned the 3rd light beam that produces from above-mentioned the 1st diffraction structure, be subjected to diffraction from above-mentioned the 2nd diffraction structure and produce n23 diffraction light of above-mentioned the 3rd light beam, use n23 diffraction light of above-mentioned the 3rd light beam to carry out regeneration and/or record, wherein for the information of above-mentioned the 3rd optical information recording media

(n22 n23) satisfies in the combination of said n 22 and n23

(n22, n23)=(2,1), in (0,1) and (1,0) any.

61. according to the described divergent angle-converting element of claim 45, it is characterized in that,

Above-mentioned the 2nd light beam as parallel light emergence.

62. according to the described divergent angle-converting element of claim 45, it is characterized in that,

This divergent angle-converting element is plastic.

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