CN1385844A - Optical head - Google Patents
Optical head Download PDFInfo
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- CN1385844A CN1385844A CN 02118978 CN02118978A CN1385844A CN 1385844 A CN1385844 A CN 1385844A CN 02118978 CN02118978 CN 02118978 CN 02118978 A CN02118978 A CN 02118978A CN 1385844 A CN1385844 A CN 1385844A
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- laser
- laser diode
- recording media
- optical path
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Abstract
The invention provides an optical head device capable of preventing fluctuation in the output of a laser diode by a return light by suppressing high frequency superimposition on power supply when laser beams of different wave lengths are converged on an optical recording medium by using a common optical lens to reproduce information or the like. In the first and second laser diodes 11 and 12 of an optical head device 1, optical path lengths L1 and L2 from light emitting points 11a and 12a to the recording surface 7a of an optical recording medium are set to lengths which are multiplication of values (1/2+m1, 1/2+m2) obtained by adding 1/2 to optional integers to resonator optical path lengths n1d1 and n2d2 constituting the first and second diodes 11 and 12. Thus, since the first and second optical path lengths L1 and L2 are not integral multiples of the resonator optical lengths, fluctuation in the output of the laser diode by return light noise is prevented by suppressing high frequency superimposition on power supply.
Description
Technical field
The present invention relates to be used in the optical-head apparatus in the record reproducing of optical recording media of CD (compressed disc) or DVD (Digital video disc) etc.More specifically, relate to following such optical-head apparatus, promptly utilizing shared object lens to make the different laser convergence of wavelength to optical recording media and when the playback of the information of carrying out, record, can prevent the change of the laser diode output that causes because of back light.
Background technology
As optical-head apparatus, the so-called dual wavelength optical-head apparatus of the laser diode in the laser diode in the 650nm of the known DVD of possessing playback usefulness band territory and the 780nm band territory that the CD-R playback of recorded is used.For example in the fair 1-56455 communique of spy, disclose the optical-head apparatus that this form is arranged.
As this communique discloses, in the dual wavelength optical-head apparatus, for miniaturization and the densification that obtains device, the optical system of shared each laser and common optical elements.For example, possess the 1st and the 2nd laser diode of the different laser of emission, converge to optical recording media by the beam splitter guiding common optical path of synthetic light path and by the public object lens that are configured in the light path from these laser diode emitted laser.
Here, the laser diode that is adopted in the optical-head apparatus is the dual heterogeneous structure of sandwich-like for the both sides of for example using gallium aluminum arsenide (GaAlAs) to hold the crystallization of gallium arsenide (GaAs) under the arm.Middle gallium arsenide layer is the laser medium that produces light by gallium aluminum arsenide power supply laterally, simultaneously, it also as crystallization is split into the right angle with optical axis so that both ends of the surface become the resonator of catoptron.Utilize this resonator, amplify the light produced and from the luminous point emission of laser diode.
Set the configuration relation of the 1st laser diode in the dual wavelength optical-head apparatus and the 2nd laser diode according to the multiplying power of optical system, the operating distance of public object lens (focal length).Usually, dispose the 1st laser diode and the 2nd laser diode so that the optical path length of the record surface from the luminous point to the optical recording media equates.
Yet when situation that the optical path length from two laser diodes to optical recording media equates, the optical path length from a laser diode to optical recording media is the integral multiple of optical path length of the resonator of this laser diode sometimes.At this moment, owing between laser diode and optical recording media, constitute resonator, in by the back light of optical recording media reflection and directive laser diode, produce standing wave (noise).Because noise turns back to laser diode, laser diode can produce the change of output sometimes.
For fear of such unfavorable condition, in the past, overlapped high-frequency electric current on the drive current of laser diode made the back light noise can not produce harmful effect to the laser diode resonator.Yet, when the stack degree is big,, and be easy to generate EMI (electric wave obstruction) noise though the back light noise diminishes, as its countermeasure metallic shield box or noise filter need be set.
Therefore, the invention provides a kind of optical-head apparatus, adopting public object lens to make the different laser convergence of wavelength to optical recording media and when carrying out information playback etc., can not carry out because of the high frequency stack feed that produces, perhaps can suppress to minimum degree the generation of EMI, by only carrying out to less degree the high frequency stack, can prevent the output change of the laser diode that back light causes.
Summary of the invention
In order to address the above problem, optical-head apparatus of the present invention has: the 1st laser diode of launching the 1st laser; Launch the 2nd laser diode of 2nd laser different with the 1st optical maser wavelength; Make from the 1st laser of the 1st and the 2nd laser diode emission and the optical system of the 2nd laser guide optical recording media, it is characterized in that, and when the refractive index of establishing the 1st resonator that constitutes described the 1st laser diode is n1, length is d1, when arbitrary integer is m1, the luminous point of described the 1st laser diode is L1=(1/2+m1) n1d1 to the 1st optical path length L1 of the record surface of described optical recording media, when the refractive index of establishing the 2nd resonator that constitutes described the 2nd laser diode is n2, length is d2, when arbitrary integer was m2, the luminous point of described the 2nd laser diode was L2=(1/2+m2) n2d2 to the 2nd optical path length L2 of the record surface of described optical recording media.
In optical-head apparatus of the present invention, set the 1st and the 2nd laser diode, make the optical path length of record surface not be the integral multiple of the optical path length of the resonator that constitutes the 1st and the 2nd laser diode from each luminous point to described optical recording media, thus, can prevent the output change of the laser diode that the back light noise causes.
Here, described optical system then can be simplified optical system as if the public object lens that possess both direct light recording mediums of described the 1st laser and described the 2nd laser.Similarly, described optical system preferably possesses the public photo detector of reception by the described the 1st and the 2nd laser of described optical recording media reflected back.
The accompanying drawing summary
Fig. 1 is the organigram of the optical system of expression optical-head apparatus of the present invention.
Embodiment
Below, describe with reference to the example of accompanying drawing for optical-head apparatus of the present invention.
(general structure)
Fig. 1 represents the organigram of optical system of the optical-head apparatus of this example.This routine optical-head apparatus 1 carries out information playback etc. for substrate thickness or the different polytype optical recording media 7 of recording density of CD, CD-R, DVD etc., and it possesses emission wavelength is that the 1st laser diode 11 of the 1st laser H1 in 780nm band territory is the 2nd laser diode 12 and the public optical system Ho of the 2nd laser H2 in 650nm band territory with emission wavelength.
Between the 1st laser diode 11 and public optical system Ho, configuration will be from the magnification transformable lens 2 that carry out magnification transformable of the 1st laser of the 1st laser diode emission.Between the 2nd laser diode 12 and public optical system Ho, the catoptron 3 that changes the direction of the 2nd laser towards public optical system Ho is set again.
In public optical system Ho configuration make to see through by magnification transformable lens 2 carry out the 1st laser H1 behind the magnification transformable and reflected back by catoptron 3 changed the 2nd laser H2 of direction beam splitter 4, make the laser H1 that comes by beam splitter 4 guiding, collimation lens 5 that H2 becomes directional light, will converge to the object lens 6 of the record surface 7a of optical recording media 7 from collimation lens 5 emitted laser H1, H2.
Again, public photo detector (not shown) is set also in public optical system Ho, this public photo detector is used to receive by the record surface 7a of optical recording media 7 reflection afterwards by the 1st laser H1 of beam splitter 4 and the back light of the 2nd laser H2.
In the optical-head apparatus 1 of such structure, when CD-R carries out playback information etc., be the 1st laser H1 of 780nm from the 1st laser diode 11 emission wavelengths as optical recording media 7.The 1st laser H1 is by the public optical system Ho of beam splitter 4 guiding, on the record surface of CD-R, be converged to hot spot by object lens 6, back light by the 1st laser H1 after the reflection of the record surface of CD-R converges to public photo detector, utilizes the information playback record that is carried out CD-R by the detected signal of public photo detector.
To this, when DVD carries out information playback etc., be the 2nd laser H2 of 650nm from the 2nd laser diode 12 emission wavelengths as optical recording media 7.The 2nd laser H2 also is directed to public optical system Ho by beam splitter 4, and by being converged to hot spot by object lens 6 at the record surface of DVD, the back light of the 2nd laser H2 that is come by the record surface reflection of DVD converges to public photo detector.The information playback of DVD etc. is carried out in utilization by the detected signal of public photo detector.
(allocation position of laser diode)
Here, set optical path length L1 and optical path length L2 respectively separately from the luminous point 12a of the 2nd laser diode to the record surface 7a of optical recording media 7 from the luminous point 11a of the 1st laser diode 11 to the record surface 7a of optical recording media 7.In this example, the 1st optical path length L1 is shorter than the 2nd optical path length L2.Again, explanation described as follows, optical path length L1, L2 represent the air characteristic chamber length of optics, in Fig. 1, expression can be ignored the thickness of optics.
Again, between the 1st laser diode 11 and beam splitter 4, magnification transformable lens 2 are set,, utilize public object lens 6 that the 1st laser H1 and the 2nd laser H2 are converged to optical recording media 7 by the multiplying power of conversion the 1st laser H1.Only described the reasons are as follows of side configuration magnification transformable lens 2.Because recording the 1st laser H1 of CD-R can make more optical convergence to optical recording media 7 by carrying out magnification transformable by magnification transformable lens 2 in order to carry out the information record.Again, when the 2nd laser H2 of usefulness that DVD is reset is transformed into the multiplying power identical with the 1st laser H1, light quantity decay around object lens 6 apertures, actual NA reduces and the reproduction quality deterioration, so preferably do not make it see through magnification transformable lens 2 and converge directly on the optical recording media 7.
In this example, as following, set the 1st optical path length L1.When the refractive index of the resonator that make to constitute the 1st laser diode 11 be n1, when length is d1, the resonator optical path length of this laser diode is expressed as n1d1.When optical path length L1 was the integral multiple of resonator optical path length, because the optical noise that returns, the output of laser can produce change.Therefore, when establishing arbitrary integer and be m1, setting optical path length L1 as following.
L1＝(1/2+m1)n1d1
Similarly, when the 2nd optical path length L2 multiply by the integral multiple of the 2nd resonator optical path length n2d2 of length d 2 for the refractive index n 2 of the resonator that constitutes the 2nd laser diode 12, because the output of back light noise laser produces change.Therefore, when establishing arbitrary integer and be m2, setting optical path length L2 as following.
L2＝(1/2+m2)n2d2
So, in optical-head apparatus 1, set the 1st and the 2nd laser diode 11,12, so that optical path length L1, the L2 of the record surface 7a from each luminous point 11a, 12a to optical recording media be not for constituting the integral multiple of the resonator optical path length of the 1st and the 2nd laser diode respectively.Therefore, can prevent the output change of the laser diode that the back light noise causes.
Thus, there is no need feed for laser diode and carry out the high frequency stack and make that the back light noise is strong resonant condition overcoming the influence to amplification in the resonator, so do not need to implement an EMI countermeasure accordingly for high frequency stack institute.
Again, by at the configuration of the light path from the 1st laser diode 11 or the 2nd laser diode 12 to public object lens 6 magnification transformable lens 2, can adopt public object lens 6 to make the 1st and the 2nd laser H1, H2 converge on the record surface of optical recording media 7 with optimum condition.
Again, the optical-head apparatus of the foregoing description is made of 2 laser diodes and a public photo detector of configuration respectively, and for the optical-head apparatus that is installed in the twin-laser of 2 laser diodes of configuration in the box, dispose the optical-head apparatus of 2 corresponding separately 2 photo detectors of laser diode, the optical-head apparatus of the laser diode of configuration more than 3 and the optical-head apparatus that possesses the corresponding separately a plurality of object lens of a plurality of laser diodes and/or a plurality of photo detectors, dispose each laser diode, so that being resonator optical path length and arbitrary integer, the optical path length from the luminous point to the optical recording media adds product after 1/2, so, can prevent the output change of the laser diode that back light causes.
As mentioned above, in optical-head apparatus of the present invention, set the 1st and the 2nd laser diode, so that the optical path length till from luminous point separately to the record surface of described optical recording media is not the integral multiple of the resonator optical path length that constitutes the 1st and the 2nd laser diode.Thus, can prevent the output change of the laser diode that the back light noise causes.
Claims (3)
1. an optical-head apparatus has: the 1st laser diode of launching the 1st laser; Launch the 2nd laser diode of 2nd laser different with the 1st optical maser wavelength; And will it is characterized in that from the 1st laser of the 1st and the 2nd laser diode emission and the optical system of the 2nd laser guide optical recording media,
If n1 is that length, m1 are arbitrary integer for refractive index, the d1 of the 1st resonator that constitutes described the 1st laser diode, then the 1st optical path length L1 from the luminous point of described the 1st laser diode to the record surface of described optical recording media is
L1＝(1/2+m1)n1d1，
If n2 is that length, m2 are arbitrary integer for refractive index, the d2 of the 2nd resonator that constitutes described the 2nd laser diode, then the 2nd optical path length L2 from the luminous point of described the 2nd laser diode to the record surface of described optical recording media is L2=(1/2+m2) n2d2.
2. optical-head apparatus as claimed in claim 1 is characterized in that,
Described optical system possesses the public object lens with described the 1st laser and both direct light recording mediums of described the 2nd laser.
3. optical-head apparatus as claimed in claim 1 is characterized in that,
Described optical system possesses the public photo detector of the described the 1st and the 2nd laser that reception reflected by described optical recording media.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001140125 | 2001-05-10 | ||
| JP2001140125A JP2002334470A (en) | 2001-05-10 | 2001-05-10 | Optical head device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1385844A true CN1385844A (en) | 2002-12-18 |
| CN1224020C CN1224020C (en) | 2005-10-19 |
Family
ID=18986783
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 02118978 Expired - Fee Related CN1224020C (en) | 2001-05-10 | 2002-05-10 | Optical head |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP2002334470A (en) |
| CN (1) | CN1224020C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111936799A (en) * | 2018-04-04 | 2020-11-13 | 株式会社Kelk | Fluid heating device |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007080925A1 (en) * | 2006-01-12 | 2007-07-19 | Matsushita Electric Industrial Co., Ltd. | Optical pickup device and information processor provided with such optical pickup device |
| JP6167405B2 (en) * | 2012-04-02 | 2017-07-26 | パナソニックＩｐマネジメント株式会社 | Optical pickup and optical disc apparatus |
-
2001
- 2001-05-10 JP JP2001140125A patent/JP2002334470A/en active Pending
-
2002
- 2002-05-10 CN CN 02118978 patent/CN1224020C/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111936799A (en) * | 2018-04-04 | 2020-11-13 | 株式会社Kelk | Fluid heating device |
| US11985736B2 (en) | 2018-04-04 | 2024-05-14 | Kelk Ltd. | Fluid heating device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1224020C (en) | 2005-10-19 |
| JP2002334470A (en) | 2002-11-22 |
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| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C56 | Change in the name or address of the patentee |
Owner name: NIDEC SANKYO CORP. Free format text: FORMER NAME OR ADDRESS: SANKYO SEIKI MFG. SEISAKUSHO K.K. |
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| CP01 | Change in the name or title of a patent holder |
Address after: Nagano Patentee after: Sankyo Seiki Seisakusho KK Address before: Nagano Patentee before: Sankyo Seiki Manufacturing Co., Ltd. |
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| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20051019 |