CN1116712A - Beam shaping prism for optical disc recorder - Google Patents
Beam shaping prism for optical disc recorder Download PDFInfo
- Publication number
- CN1116712A CN1116712A CN95106631A CN95106631A CN1116712A CN 1116712 A CN1116712 A CN 1116712A CN 95106631 A CN95106631 A CN 95106631A CN 95106631 A CN95106631 A CN 95106631A CN 1116712 A CN1116712 A CN 1116712A
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- Prior art keywords
- light
- prism
- incident
- exit facet
- incidence
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1359—Single prisms
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1365—Separate or integrated refractive elements, e.g. wave plates
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- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Head (AREA)
Abstract
A beam shaping prism is provided, which is used for an optical disk recorder. The beam shaping prism is designed like that, the prism is provided with an incident face which is used for receiving oblique incidence beam and reflecting the incidence beam in order to expand the beam in shape, a perfect reflection face which is used for perfectly reflecting the incidence beam, and an outgoing face which is used for refracting the perfect reflection beam to be beam which is perpendicular to the incident beam. The outgoing face is provided with an included angle with 45 degrees relative to the direction of the incidence beam. According to the structure, beam detecting components can be arranged horizontally compared with the other optical components, consequently making the optical system with simple structure. Due to a fractional polarization separated coating is coated on the outgoing face of the prism, an individual fractional polarizing beam splitter is unnecessary.
Description
The present invention relates to the beam shaping prism of the shaven head of optical recorder, particularly a kind of prism, it is designed to have a plane of incidence and an exit facet, at plane of incidence place, incident beam is formed, so that its expanded in diameter, the outgoing beam at exit facet place is perpendicular to incident beam, with exit facet angle at 45.
In general, the semiconductor laser as the light source of optical recorder vertically has different beam emissions angles with horizontal direction.Typical emission angle ratio is 2: 1 to 3: 1.Because this different beam emissions angle ratio vertically has different intensity distributions with horizontal direction after light beam is subjected to once collimating.What in other words, the collimation back was penetrated is elliptical beam.This elliptical beam is used to reduce the signal to noise ratio (S/N ratio) of whole optical system.For this reason, the optical system of common optical recorder is used a prism or cylindrical lens, will be configured as a circle from semiconductor laser instrument emitted light beams.Be explained in detail with reference to figure 1.
Fig. 1 shows a common optic pick-up system.One light beam penetrates with different levels and Vertical Launch angle from a laser diode 1, as shown in Figure 1.Light beam from laser diode 1 passes a collimator lens 2 again, becomes a parallel beam.Since because of different levels and vertical emergence angle caused vertically and the distribution of the different light intensity in the horizontal direction, this parallel beam ovalize.Then, this bundle incides on the shaping prism 3 from the light that collimator lens 2 penetrates.Because the light beam oblique incidence is to shaping prism 3, so light intensity evenly distributes, and is for example rounded.After passing shaping prism 3, light beam can be along an optical axis emission of a perpendicular or parallel optical axis in other optical element.Incide on a part of polarized light separator 4 from the light beam of shaping prism 3 outgoing.After passing this partial polarization light separator 4, light beam is by a catoptron 5 reflections.Reflected light incides on the CD 7 through object lens 6 again, thereby data are write on the CD 7, perhaps, and when light during polarization, is fed on dish 7 recorded data corresponding direction.Detected lens 8 by 4 reflections of partial polarization light separator to pass one again from the light beam of CD 7 feedbacks.Enter a polarized light separator 9 from the light beam that detects lens 8 outgoing, result, the light beam that this polarized light separator becomes to have the different polarization direction with this beam separation.The light beam that is separated by polarized light separator 9 is focused on respectively on the optical detector 10.
But, have said apparatus optical system since the optical axis of laser diode 1 and collimator lens 2 both out of plumb also be not parallel to the optical axis of other optical element, but with its inclination, the difficulty that this has just caused the supporting mechanism of the element of making this optical system and assembling and has adjusted optical element.And the element of this optical system occupies very big space, and the weight of whole optic pick-up system is increased.
For overcoming the shortcoming of this tilting gearing, the someone has advised a kind of beam-shaping structure that comprises two prisms or cylindrical lens.This structure is shown in Fig. 2 A and Fig. 2 B.
Fig. 2 A shows a beam-shaping system, and it has used the pair of upright prism.One oval-shaped beam penetrates from a laser diode 1, enters a collimator lens 2, and it is transformed into a parallel beam with light beam.This parallel beam passes pair of upright prism 11 again, because its refraction action, light beam is shaped as circle.In this structure and since from the optical axis deviation of optical system outgoing beam the optical axis of laser diode 1, though the two is parallel to each other, also brought difficulty to assembly working.And upright prism need accurately be positioned at required angle.This makes mechanism's profile complexity of support of optical system element.
On the other hand, Fig. 2 B shows a beam-shaping optical system, and it has adopted a pair of cylindrical lens.A branch of oval-shaped beam that sends from laser diode 1 enters a collimator lens 2, and it is transformed into a parallel beam with this light beam.Parallel beam enters a pair of cylindrical lens 12 again, and each cylindrical lens only has radian in the horizontal direction.Cylindrical lens 12 is used for flatly expanding beam diameter, thereby is circular with beam-shaping.Though the optical axis of the optical axis alignment incident light of emergent light in this optical system, this needs the cylindrical lens height accurately just can reach this aligning.And this structure has a shortcoming, be level or be arranged vertically owing to be used for the optical element of beam-shaping, thereby total is huge.
In sum, adopt the optical axis of the ordinary construction of an independent prism to tilt mutually, and adopt the optical axis of common structure of two prisms parallel, but be offset mutually.On the other hand, adopt the common structure of two cylindrical lens, though optical axis aligns fully, structure is huge, and element is difficult to be made.
Therefore, an object of the present invention is to provide a kind of beam shaping prism that is used for an optical disc recorder, a plane of incidence and an exit facet have been designed to, be shaped so that the beam diameter expansion at plane of incidence place incident light, at exit facet place emergent light perpendicular to incident light, and be 45 with exit facet, thereby, the light beam of CD reflection all reflexes on the vertical direction on the exit facet, therefore make the outgoing parallel light in incident light, thereby the member supports mechanism that makes the optic pick-up system of optical disc recorder is easy to make, and the structure of optic pick-up system is reduced.
According to the present invention, this purpose can reach like this, one beam shaping prism promptly is provided, be used for the optic pick-up system internal shaping incident beam at an optical disc recorder, this prism has a polyhedral structure, comprising: building mortion, be used for changing with vertical direction in the horizontal direction the intensity distributions heterogeneous of incident beam, make light distribution even, and produce an outgoing beam perpendicular to incident light axis, so this optic pick-up system is that vertical/horizontal is arranged.
According to the present invention, building mortion comprises: thus one be used for receiving irradiating light beam obliquely and reflect this incident beam to this beam-forming so that the plane of incidence of its expansion; One is used for the fully reflecting surface and of incident beam total reflection is used to reflect above-mentioned total reflection light beam, makes from the light beam of its ejaculation exit facet perpendicular to incident beam, and the direction of this exit facet and incident beam is inclined to 45.
By the description of embodiments of the invention being done below in conjunction with accompanying drawing, purpose of the present invention and others are conspicuous.
Fig. 1 is the synoptic diagram of the optic pick-up system of the common optical disc recorder of an expression;
Fig. 2 A is the synoptic diagram of the beam-shaping optical system of the common employing pair of upright prism of an expression;
Fig. 2 B is the synoptic diagram of the beam-shaping optical system of the common a pair of circle lens of employing of an expression;
Fig. 3 is the design diagram of an explanation according to the beam shaping prism of optical disc recorder of the present invention;
Fig. 4 is that the synoptic diagram of limit according to the optical system of the optical disc recorder of beam shaping prism of the present invention adopted in an expression one;
Fig. 3 is a synoptic diagram, and the design according to the beam shaping prism of optical disc recorder of the present invention has been described.
As shown in Figure 3, beam shaping prism of the present invention has a plane of incidence a, is used to reflect the light beam of oblique incidence thereon, to this beam-shaping so that its expansion.This beam shaping prism also has a fully reflecting surface b, is used for a total reflection incident light and an exit facet c, is used to reflect this total reflection light, makes light beam from its outgoing perpendicular to former incident beam.Exit facet c tilts 45 ° with respect to former incident direction of light.
The exit facet c of this beam shaping prism is coated with partial poolarized light and separates coating, makes it play the effect of a partial polarization light separator.
Beam shaping prism work with said structure is as follows.
The a branch of smooth oblique incidence of penetrating from laser diode is to the plane of incidence a of prism.This incident beam throwing is at the fully reflecting surface b of prism then.Incident beam is shaped to expansion when passing prism to fully reflecting surface b from plane of incidence a.The light beam that forms arrives fully reflecting surface b like this, is totally reflected to exit facet c by fully reflecting surface b again.This incident beam is shaped to shrink when fully reflecting surface b passes prism to exit facet c.Though light beam is shaped at exit facet c place and shrinks, compare with former incident light, total has still expanded.Because the structure of exit facet c makes itself and former incident direction of light angle at 45, it is used to make the light beam that feeds back from CD to reflect inciding the perpendicular direction of the direction of exit facet c with this light beam.As a result, the optical axis of the outgoing beam before the photodetector is parallel to from the optical axis of the light beam of laser diode ejaculation.Separate coating owing to scribble the partial polarization light beam on the exit facet c, this prism can be used as the partial polarization light separator.
In Fig. 3, angle between label α 1 expression plane of incidence a and the exit facet c, α 2 is the angle between plane of incidence a and the fully reflecting surface b, α 3 expresses the angle of irradiating light beam with respect to plane of incidence a, α 4 expresses the angle between irradiating light beam and the exit facet c, θ 1 is the beam incident angle at plane of incidence a place, and θ 2 is the refraction of optical beam angle at plane of incidence a place.θ 3 is for being all-trans the angle of total reflection of light beam at fully reflecting surface b place, θ 4 is the incident angle of light beam at exit facet c place, θ 5 is the refraction angle of light beam at exit facet c place, δ 1 is one by the incident light of plane of incidence a refraction and the angle between the emergent light, δ 2 is an angle that limits between by the light beam of fully reflecting surface b total reflection and emergent light, and δ 3 is the incident light at fully reflecting surface b place and the angle between the fully reflecting surface b.
Angle α 4 between emergent light and exit facet c is decided to be 45 °, because the setting of exit facet c makes itself and former incident direction of light form 45.Similar with it, the refraction angle θ 5 at exit facet c place is decided to be 45 °.
In beam shaping prism of the present invention, the enlargement ratio M1 of refractive index N, plane of incidence a, the enlargement ratio M2 of exit facet c and total enlargement ratio M have particular kind of relationship to each other.The back will illustrate this.
The incident angle θ 4 at exit facet c place and enlargement ratio M2 can derive as follows by the snell law about refraction:
SINθ5＝NSINθ4
Equation (1) and (2) of M2 COS θ 4=COS θ 5 below top equation can be derived
Simultaneously, the enlargement ratio M1 of plane of incidence a has following relation with the enlargement ratio M2 of total enlargement ratio M and exit facet c:
M1＝M/M2 (3)
Utilize snell law also can derive as follows with refraction angle θ 2 the incident angle θ 1 at plane of incidence a place:
SINθ2＝NSINθ2
M1COSθ1＝COSθ2
Equation below top equation can be derived (4) and (5):
θ1＝COS
-1{(N
2－1)/N
2M1
2－1}
1/2 (4)
θ1＝SIN
-1(SINθ1/N)＝COS
-1(M1COSθ1) (5)
About the angle α 2 between plane of incidence a and the fully reflecting surface b
δ1＝90－(θ1－θ2)，
δ2＝θ5－θ＝45－θ4，
(6)
θ3＝(180－δ1－δ)/2，
δ3＝90－θ3
α2＝180－(90－θ2)－δ3＝90＋θ2－δ3 (7)
About α 1, α 3 and α 4
Lifting an example explanation below, is that 2 glass is made a beam shaping prism with a refractive index, presses above-mentioned relation, and always enlargement ratio is 2.
In this example, utilize equation (1) to (5) can derive the incident angle θ 1 at plane of incidence a place, the incident angle θ 4 at exit facet c place, the refraction angle θ 2 at plane of incidence a place, the refraction angle θ 5 at exit facet c place, the enlargement ratio M2 at the enlargement ratio M1 at plane of incidence a place and exit facet c place, as follows:
M1＝M/M2＝2.4944θ1＝COS
-1{(N
2－1)/(N
2M1
2－1)}
1/2＝71.9355，θ1＝SIN
-1(SINθ1/N)＝COS
-1(M1COSθ1)＝39.3314°
Can derive angle α 1 to α 4 required when making and assembling this light beam and forming prism with (7) and (8) formula, as follows:
δ1＝90－(θ1－θ2)＝57.3959°，
δ2＝θ5－θ4＝45－θ4＝16.8745°，
θ3＝(180－δ1－δ2)/2＝52.8648°
δ3＝90－θ3＝37.1352°
Therefore,
α2＝1890－(90－θ2)－δ3＝90＋θ2－δ3＝92.1962°
For angle α 1, α 2 and α 4
α4＝450°
α3＝θ1＝71.9355°
α1＝180－α3－α4＝135－θ1＝63.0645°
With top factor, can make a required beam-shaping prism.
Fig. 4 shows the optical system of the optical recorder that adopts beam shaping prism of the present invention briefly.Among Fig. 4 used element corresponding among Fig. 1 use with Fig. 1 in identical label.
In this optical system, a light beam penetrates from a laser diode 1 with different levels and Vertical Launch angle.Light beam from laser diode 1 passes a collimator lens 2 again, and this collimator lens 2 becomes this light beam into parallel beam, and this parallel beam is oval, because different levels makes it with horizontal direction different light distribution be arranged vertical with the Vertical Launch angle.The light beam that penetrates from collimator lens 2 incides on the beam shaping prism with structure of the present invention.This beam shaping prism marks with label 20.Because the light beam oblique incidence is to the plane of incidence a of beam shaping prism 20, it is to the fully reflecting surface b of beam shaping prism 20 refraction.When incident beam is shaped to expansion when plane of incidence a passes prism 20 to fully reflecting surface b.The light beam that forms arrives fully reflecting surface b like this, is totally reflected to exit facet c by fully reflecting surface b.When this light beam when the exit facet c of prism 20 penetrates, c is refracted again at exit facet.The light distribution of outgoing beam as a result is changed.In other words, outgoing beam with exit facet c angle at 45, therefore has a uniform circular intensity perpendicular to former incident direction of light.Reflected by a catoptron 5 again from the outgoing beam of prism 20 outgoing, light beam is spread direction and is turned over 90 °.Beam reflected incides on the CD 7 through object lens 6 again, thereby its data are write on the CD 7, perhaps produces polarization on corresponding to a direction that is recorded in the data on the CD 7 and is fed.The light beam that returns from CD 7 mirror 5 that is reflected again reflexes to the exit facet c of prism 20.Because being coated with the partial polarization light beam, the exit facet c of prism 20 separates coating, its vertical reflection light beam.Pass detection lens from prism 20 beam reflected and arrive a polarized light separator 9, the light beam that this polarized light separator 9 becomes to have the different polarization direction again to this beam separation.Be focused on respectively on the photodetector 10 again from polarized light separator 9 isolated light beams.
By above-mentioned apparent, the invention provides beam-shaping lens that are used for optic pick-up system, its structure can become its optical axis is parallel to or perpendicular to the light beam of formed thereby with the arrangements of elements of optic pick-up system, thereby the mechanism that makes supporting optical component is easy to make, and obtains the optic pick-up system of closely knit layout.
According to the present invention, the exit facet of prism is at 45 with the direction inclination of the light beam that penetrates from it, therefore, incides the direction of exit facet perpendicular to light beam from the exit facet beam reflected.With this structure, the element that detects light beam can be horizontally disposed with respect to other optical element, thereby obtain a simple optical system device.Separate coating because the exit facet of prism is coated with the partial polarization light beam, do not need any independent polarization beam splitter.
Though it is for illustrating, disclose preferential example of the present invention, the people who is familiar with this area knows, can make various improvement under the prerequisite that does not break away from the disclosed scope and spirit of the present invention of claim, additional and alternative.
Claims (3)
1. beam shaping prism that is used at optic pick-up system internal shaping one incident beam of an optical disc recorder, this prism has a polyhedral structure, comprise: building mortion, being used in the horizontal and vertical directions, the incident light of non-homogeneous intensity distributions changes over uniform intensity distributions, and produce an outgoing beam perpendicular to the optical axis of incident beam, thereby make this optic pick-up system that the layout of one vertical/horizontal be arranged.
2. a beam shaping prism as claimed in claim 1 is characterized in that, this building mortion comprises:
One light beam that receives oblique incidence is also with this incident beam reflection, thus the plane of incidence that this beam shape is expanded;
One is used for the fully reflecting surface with this incident beam total reflection;
Be used for this total reflection light beam is reflected into an exit facet perpendicular to the light beam of this incident beam with one, the direction of exit facet and incident beam is 45.
3. a beam shaping prism as claimed in claim 2 is characterized in that, this exit facet is coated with one deck partial poolarized light and separates coating, thereby can be used as the part light polarizer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR14686/94 | 1994-06-24 | ||
| KR1019940014686A KR0125962B1 (en) | 1994-06-24 | 1994-06-24 | Beam prism for optical disc recording device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1116712A true CN1116712A (en) | 1996-02-14 |
Family
ID=19386292
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN95106631A Pending CN1116712A (en) | 1994-06-24 | 1995-06-23 | Beam shaping prism for optical disc recorder |
Country Status (2)
| Country | Link |
|---|---|
| KR (1) | KR0125962B1 (en) |
| CN (1) | CN1116712A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108700752A (en) * | 2016-03-08 | 2018-10-23 | 卡尔蔡司Smt有限责任公司 | Realize the beam splitter of the glancing incidence of light |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100485746B1 (en) * | 1998-03-20 | 2005-08-10 | 삼성전자주식회사 | Liquid crystal display apparatus having protection function caustic surface |
| KR100559960B1 (en) * | 1999-01-14 | 2006-03-13 | 삼성전자주식회사 | Picture display module for data processing apparatus |
| KR100765538B1 (en) * | 2000-12-29 | 2007-10-10 | 엘지.필립스 엘시디 주식회사 | Backlight Unit using the Reflector Housing Lamp |
| KR100446726B1 (en) * | 2001-11-27 | 2004-09-01 | 엘지전자 주식회사 | Apparatus for near field optical recorder |
| KR20220150610A (en) * | 2021-05-04 | 2022-11-11 | 삼성전자주식회사 | Display apparatus |
-
1994
- 1994-06-24 KR KR1019940014686A patent/KR0125962B1/en not_active IP Right Cessation
-
1995
- 1995-06-23 CN CN95106631A patent/CN1116712A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108700752A (en) * | 2016-03-08 | 2018-10-23 | 卡尔蔡司Smt有限责任公司 | Realize the beam splitter of the glancing incidence of light |
Also Published As
| Publication number | Publication date |
|---|---|
| KR960002204A (en) | 1996-01-26 |
| KR0125962B1 (en) | 1997-12-26 |
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