JPH01251439A - Light source unit - Google Patents

Abstract

PURPOSE:To obtain a light source unit for an optical unit easily manufactured, miniaturized, and made into light weight by rotating a polarizing plane on one side of source light with different wavelength from light emitting bodies whose light emission openings are arranged so as to intersect orthogonally with each other by 90 deg., and converting the beam shape of both light by a light transmissive optical member. CONSTITUTION:On a mount 3 provided obliquely on a substrate 4, elliptical LEDs 6 and 7 whose light emission openings are set so as to intersect orthogonally with each other are embedded, and elliptical pattern laser beams whose polarizing planes are intersected orthogonally to each other and with different wavelength are outputted from the LEDs 6 and 7. And the polarizing plane of the laser beam on one side is rotated by 90 deg. by a lambda/2-wave plate 8, and the laser beams L1 and L2 whose polarizing planes are arranged are collimated by the light transmissive member 1 of glass material provided on an elliptical aperture plane, and also, elliptical polarized light is corrected to circularly polarized light, then, they become the laser beams for information read, focusing, and tracking. Therefore, it is possible to generate the light source unit having two LED chips as a single optical member easily, and to obtain the light source unit for optical head simplified and made into light weight.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a light source device, and particularly relates to a light source device for an optical head used in an optical recording/reproducing device.

[Background Art] In recent years, optical disk devices have been viewed as promising as file devices that convert vast amounts of information into electronic files. In an optical disk device, a light beam is irradiated onto a medium on which information is recorded, and the recorded information is read out by the reflected or transmitted light beam.

In addition, in a different type of optical disk device from the optical disk device described above, recorded information is read out by a light beam irradiated onto the recording surface of the optical disk, and information is read out using the light beam. Inclusion and deletion are performed.

The various optical disk devices mentioned above use semicircular lasers as light sources for reading information from optical disks, writing information to optical disks, and erasing information signals written on optical disks. Diode (LD chip) or C
1^ I'm excited. The LD chip has a roughly J-shaped body shape with a side length of several hundred μm, and its light emitting opening is 1 μm in the contraction direction.
m, and is formed as small as a few μm in the lateral direction. Since the area of the exit aperture is small, the light beam that is even emitted from the exit exit is diverged by diffraction. This divergence angle is
The beam cross section is different in the longitudinal direction (long axis direction) from 30° to 60° and the horizontal direction (short axis direction) from 10° to 30°, and has an elliptical shape. Furthermore, the elliptical light beam emitted from the LD chip has a characteristic of being linearly polarized in the short axis direction of the elliptical surface. As mentioned above, the light beam emitted from the LD chip is a diverging light beam having a specific angle and has an elliptical cross section. When used as the recording optical beam 11, it cannot be used directly.

Therefore, the optical disk device is equipped with a collimator lens 13 that corrects the elliptical diverging light emitted from the LD hydrogen molecules into elliptical parallel light, as shown in FIG. An ellipse correction prism is provided to correct the shape of the light beam.

Conventionally, in a phase change/structure change type erasable optical disk device, in addition to writing and erasing information, there is an LD hydrogen element for writing and reading that emits different wavelengths, and an LD hydrogen element for erasing. Two LD hydrogen atoms are required. The light beam emitted from the LD hydrogen element for writing and reading is corrected into a light beam with a circular cross section by the above-mentioned collimator lens and ellipse correction prism, and is converted into a light beam of a specific wavelength, for example, this writing and reading light. The beam is incident on a dichroic mirror that transmits the beam.

An erasing light beam is also incident on Manako's dichroic mirror and is reflected by it. Therefore, each beam of light is combined into a coaxial beam by a dichroic mirror, and further converted into circularly polarized light by a λ/4 plate and irradiated onto the recording surface of the optical disc. A circular spot and an oblong spot are formed coaxially on the recording surface. The light beam irradiated onto the recording surface is reflected or transmitted by the recording surface of the optical disc and returned to the λ/4 plate, or when the returned light beam passes through the λ/4 plate, the incident light beam Of the light beams rotated 90 degrees with respect to the polarization plane of the tree, the erasing light beam of the returned light beams is cut by the joint surface when returned to the dichroic mirror, and is used for writing and reading by other programs. The optical beam is transmitted through the dichroic mirror, reflected by a beam splitter placed on its optical path, and detected by a photodetector. The detected light beam is used as an information reading signal, a forcing control signal, and a tracking control signal [Problem to be solved by the invention] In conventional erasable optical information recording and reproducing devices, different wavelengths Two LD elements that emit light beams are used as light sources, and the light beams are coaxially combined and utilized in writing, recalling, and erasing information. Therefore, a dichroic mirror and a λ/4 plate are required, which increases the size of the entire optical system.
In order to correct the elliptical light generated by the LD hydrogen molecules, a collimator lens and an ellipse correction prism that are separately configured are used. Therefore, the device becomes larger and more complicated.

An object of the present invention is to provide a light source device for an optical head that is easy to manufacture, compact, and lightweight.

[Means for Solving the Problems] According to the present invention, the light exit ports having long sleeves are arranged in a mutually orthogonal relationship, and first and second elliptical beams whose polarization planes are orthogonal to each other are emitted from the exit ports. first and second light sources that emit; an optical means that is arranged on the optical path of either the first or second elliptical beam and rotates the plane of polarization of the incident elliptical beam by 90 degrees; A light source device is provided, comprising a light-transmissive optical member disposed on the optical path of the second elliptical beam and converting the beam shape.

[:E (1) IJ] FIG. 1 shows a cross-sectional view of a light source device for an optical head according to an embodiment of the present invention. The light source device 10 schematically includes a laser diode 6.
7, a light transmitting member 1, a λ/2 plate 8, and a pan cage 2
It consists of The package 2 is formed into a substantially cylindrical shape, and one end thereof is closed by a substrate 4. The other end has the shape of a cylinder cut diagonally, and has an opening with an elliptical cross section.

A light-transmitting optical member 1 made of a material such as glass is attached to the opening of the package 2. On the other hand, a mount 3 is mounted on a substrate 4 provided on the package 2, the mount 3 having a surface inclined at a predetermined angle with respect to the surface of the substrate. For example, a laser diode chip (LD chip) 6.7 is attached to the mount 3 so as to emit a laser beam in the same direction. LD chip 6.7 is
As will be described in detail later, they are arranged at predetermined intervals and are arranged in such a manner that the linearly extending exit ports of the laser beams intersect with each other. Further, a λ/2 plate 8 is attached to one side of the LD chip 6.7, for example, on the optical path of the light beam emitted from the LD chip processor, and on the surface on which the stand Fi3 is attached.

Laser diode chip 6 provided in the light source device 10.
7 are arranged as shown in FIGS. 5 and 6.

5 and 6 show a light emitting device 20 obtained by removing the light transmitting optical member 1 from the light source device 10 shown in FIG. The LD chip arranged in the light emitting device 20 is composed of a horizontal laser diode chip 6 arranged horizontally on the LD mount +-27 and a vertically arranged laser diode chip 7 arranged vertically. , are arranged with a distance of 300 to 500 μm fi from each other. Furthermore, the LD chips 6.7 are arranged so as to emit mutually parallel light beams, but the emitting ports are arranged so that their long axes do not form 90 degrees with each other. Therefore, the laser beams L1 and L2 emitted from each LD chip 6.7 are emitted as elliptical beams having optical axes of W, and the directions of the long axes of the elliptical beams intersect with each other at 90 degrees. irradiated. Furthermore, the light beams L1 and L2 are linearly propagated in the direction of the short axis of the elliptical surface 2), and their polarization planes are also propagated orthogonal to each other. Further, a λ/2 plate 8 is arranged on the optical path of either the light beam L1 or L2 emitted from the LD chip 6.7 arranged in the light emitting device 20.

This λ/2 plate 8 is provided to align the polarization planes of the light beams emitted from the LD chip in the same direction. That is, the polarization planes of the light beams emitted from the LD chip are orthogonal to each other, and the polarization planes are aligned by passing through one of the optical beams or the λ/2 plate 8.

The light emitting device 20 described above has a light beam L emitted from it.
By providing the collimator lens 23 and the ellipse correction prism 22 on the optical paths of L and L2, the shape of the light source device is converted in the same way as the light source device shown in FIG. This beam conversion assumption will be explained using FIGS. 7 and 8.

7 and 8 are side views showing the optical path and beam shape when the light beams L1 and L2 emitted from the light emitting devices shown in FIGS. 5 and 6 pass through the collimator lens and the ellipse correction bulism. and a plan view. One LD chip 6 emits a diverging elliptical light beam L\L1 having the long axis of the ellipse in a direction parallel to the paper surface, and the other LD chip 6 emits a diverging elliptical light beam L\L1. ,D
The chimps 7 each emit a diverging/ratio elliptical light beam L2 having an elliptical long sleeve in a direction perpendicular to the plane of the paper.

Assuming that the ellipticity ratio of each of the elliptical light beams L1 and L2 is 1:3, in order to correct the ellipticity and make a light beam with a circular cross section, a prism 22 with an ellipticity correction factor of 3 is used.
is required. However, as mentioned above, the optical axes of the elliptical light beams L 1 and L 2 are different from each other, and the long axis of the ellipse is perpendicular to 90°, so the ratio is 1:3.
A laser beam having an elliptic shape with an ellipticity ratio of A prism 22 having a ratio of 3 is arranged. At this time, 2'L is emitted from the LD-)l pro of the light emitting device 20.
The light beam L2 is corrected into parallel light by the collimator lens 23, elliptically corrected by the prism 22, and corrected into a substantially circular light beam of 1.1. The light beam L1 emitted from the LD chip 7 is corrected into parallel light by the collimator lens 23, and is further divided into an ellipse by the prism 22.
The ellipticity ratio is reduced from 1 to 1:9. 1:
The light beam L2 having an ellipse ratio of 1 is focused by an objective lens (not shown) and is used as a recording or reproducing beam to form a sharp circular beam spot on the recording surface of an optical disk, for example. . On the other hand, the light beam L1 having an ellipticity ratio of 1:9 is focused by an objective lens (not shown) to form a wide elongated beam spot on the recording surface. It is used as a beam for erasing information.

Since each LD chip 6.7 is arranged with an interval of 300 to 500 μm, optical axis deviation occurs. Therefore, when the optical beams L1 and L2 with shifted optical axes are focused by the same objective lens, beam spots are formed at separate positions on the recording surface of the optical disc. Therefore, at the same time, Ll emitted from the vertical LD chip is used as an erasing light beam.

By using L2 emitted from the vertical LD chip as a recording and reproducing beam light, erasing and recording can be performed at the same time, and the erasing state can be inspected using the recording beam.

As mentioned above, by arranging two LD chips adjacent to each other and with their exit ports rotated by 90 degrees, a circular spot and an elongated elliptical spot can be simultaneously formed with minimal optical axis adjustment. Therefore, an optical pickup section for a two-beam type phase change optical disk that is easy to manufacture is provided. In this embodiment, Ll is used as the erasing beam and L2 is used as the recording/reproducing beam, but conversely, L2 may be used as the recording/reproducing beam and Ll as the erasing beam. The collimator lens and prism shown in FIG. 8 can be replaced with the light-transmitting optical member shown in FIG.

FIG. 9 and FIG. 1O show the function of the light-transmitting optical member l. In FIG. 9, for simplicity of explanation, a single LD chip 9 (one of the LD chips 6.7 shown at 1112) is placed within the package 12. The light beam L emitted from the LD chip 9 is emitted as an elliptical beam L having a specific divergence angle. FIG. 10 shows an optical path diagram of this light beam L. An elliptical light beam L having a specific divergence angle is incident on the aspherical part 17 of the light-transmitting optical member 1 made of glass or the like, with the long axis of the ellipse in a direction parallel to the plane of the paper, and the aberration is It is corrected to an elliptical parallel light without any

Furthermore, when the elliptical parallel light is emitted from the plane part 16 having a predetermined angle with respect to its optical axis, it is corrected into a light beam having a circular cross-section with an elliptical shape. The light-transmitting optical member 1 has a refractive index set and a surface shape molded so as to have both the function of correcting divergent light to parallel light and the function of correcting elliptical light to circular light.

In this way, the light-transmitting optical member 1 has both the function of a collimator lens that corrects the diverging light emitted from the LD chip into parallel light, and the function of an ellipse correction prism that corrects elliptical light into circular light.

Furthermore, when the LD chip 9 and the light-transmitting optical member 1 are arranged in a package 12 that is substantially similar to the present invention, the light beam L emitted from the flat surface portion 16 on the light-transmitting optical member 1 is
The package 12 is arranged so that its optical axis and the long axis of the package 12 are parallel to each other.

In the embodiment shown in FIG. 1, the above-mentioned light-transmissive optical member 1 and the light beam exit aperture are arranged at 90° to each other, and the polarization planes of the respective light beams emitted are 90° to each other. Two LD chips 6.7 are arranged so as to be rotated by .degree., and a λ/
Since all of the two plates 8 are incorporated into the package 2 as a single light source device 10, there is an advantage that the number of optical parts is reduced, and the process for installing an optical disk device etc. is simplified. be done.

FIG. 2 shows an embodiment of the invention in which the light source element 10 of the invention is applied to a reflective optical disk device.

In FIG. 2, the light beams L1 and L2 emitted from the light source device 10 enter the polarizing beam splitter 30 while being linearly polarized in the same direction, for example, in the direction perpendicular to the plane of the paper in this figure. , is reflected toward the optical disk 32 at the joint surface. reflected laser light L1,
L2 is converted into circularly polarized light when it passes through λ/4 plate 3 sheet metal 1 placed on its optical path, and circularly polarized light beams L1, L
2 is condensed by the objective lens 33 and condensed onto the recording surface 40 of the ζ optical disk 32.The condensed light beam tXL
1 and L2 on the recording surface 40 are shown in FIG.

One circular beam spot S shown in FIG. 3 is used for recording or reproducing information, and the other oblong beam spot S2 is preferably used for erasing one piece of information. The light beam irradiated onto the upper surface 40 is reflected and condensed by the objective lens 31, and passes through the λ/4 plate 3 and the metal plate 1 again, resulting in linearly polarized light whose polarization plane differs by 90 degrees from the incident light. Therefore, the light beam incident on the polarizing beam splitter 30 is transmitted through the junction surface and is incident on the beam splitter 33. The incident optical heat J\ is split at the joint surface of the beam splinter 33, and
One is focused by the condensing lens 37 and detected by the photodetector 35, and the other is condensed by the condensing lens 38 and detected by the photodetector 35.
Detected at 5. Each detected signal is used as a tracking control signal and a focal control signal. Although this embodiment is used for a reflective optical disc, it may also be used for a transmissive optical disc.

[Effects of the Invention] As explained above, in the present invention, since a light source device having two LD chimps is manufactured as a single optical member, wavelengths of 5-; There is no need to combine the light beams emitted from two 1-D chips having tr, and there is also no need for beam shaping. The light beam is manufactured to be long or parallel to the light source device, making it easy to install the device.

As a result of the above, the number of optical components required in the optical head is reduced, thereby achieving miniaturization.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a light source device that is an embodiment of the present invention, FIG. 2 is a front view showing an optical head incorporated in the light source device of the present invention, and FIG. 3 is a view showing the light emitted from the light source device of the present invention. FIG. 4 shows the state of the beam spot on the recording of the light beam.
The figure is an explanatory diagram of a conventional ellipse correction prism, and the fifth (2I) and the sixth figure are between the arrangement of the LD chip and the λ/2 plate in Figure 1 (
7171 and 8, the cross-sectional view and plan view showing the system, show the light beam emitted from the light emitting device of 5T'A and 6 when corrected by the collimator lens and the ellipse correction prism. The optical path diagram, Fig. 9 and Fig. 10i'21 is the first
FIG. 2 is an explanatory diagram of the light-transmissive optical member 1 shown in the figure. 1... Light-transmissive optical member, 2... Package, 3.
... Mount, 4... Board, 6.7.9... Light source (
LD number), 8...λ/2 plate, ]0... Light source device, l-2L 1, L2... Laser light applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] (1) first and second light sources whose light exit ports having long axes are arranged in a mutually orthogonal relationship, and which emit first and second elliptical beams whose polarization planes are orthogonal to each other from the exit ports; an optical means disposed on the optical path of either one of the first and second elliptical beams to rotate the plane of polarization of the incident elliptical beam by 90 degrees; and an optical means disposed on the optical path of the first and second elliptical beams. , and a light-transmitting optical member that converts the beam shape.