JPS63166031A - Optical pickup - Google Patents

Abstract

PURPOSE:To miniaturize an optical pickup and to lighten in weight by arranging a detecting part on a form arranging prism so that reflected light from an optical disk can be separated and detected by a form arranging plane. CONSTITUTION:A laser beam emitted from a semiconductor laser 1 is changed to a parallel ray by a collimator lens 2, and is form-arranged by the form arranging prism 9, and is stopped by an objective lens 5, and projected on the optical disk. The reflected light from the optical disk is changed to the parallel ray by the objective lens 5, and is reflected and separated at the form arranging plane of the form arranging prism 9, then, it is detected by a detector 8. The apex angle of the form arranging prism 9 is decided by the form arranging ratio of the laser beam, but by selecting a P polarizing transmission ratio Tp, an S polarizing transmission ratio Ts, a P polarizing reflectance Rp, and an S polarizing reflectance Rs at appropriate levels, it is possible to attach the function of a beam splitter which divides light on the form arranging prism. In such a way, a half mirror is not required, and it is possible to miniaturize in weight and to lighten in weight the optical pickup.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disk device capable of recording, reproducing, and erasing information using light, or a combination thereof, and particularly relates to an optical disk device that uses light to record, reproduce, and erase information, or a combination thereof. The present invention relates to an optical pickup having parts.

[Prior Art] An optical pickup is a device that reads information from or records information on an optical disc. Its basic configuration is a light source unit that irradiates light onto the optical disc, and a convergence unit that converges the light from the light source. It consists of a lens system section for irradiating light onto the optical disk, and a detection section that separates and detects reflected light from the optical disk.

Conventionally, lasers have been used as light sources, and recently, semiconductor lasers have been used because they are small, lightweight, and inexpensive.

Laser light emitted from a semiconductor laser is elliptical diffused light. An objective lens is used to focus the laser beam onto an optical disk, but the recording and reproducing ability will be higher if the spot created by focusing the light is made as small as possible.

For this purpose, the shape of the laser beam incident on the objective lens must be circular. In fact, in a magneto-optical disk device, as shown in FIG. 1, laser light emitted from a semiconductor laser is collimated by a collimator lens 2 and shaped into a circular shape by a shaping prism 3. The shaped laser beam passes through a half mirror 4, is focused by an objective lens 5, and is irradiated onto a magneto-optical disk 6. In addition, the light reflected by the magneto-optical disk is made into parallel light by the objective lens 5, and the light is converted into parallel light by the objective lens 5.
It is reflected and separated at 4, passes through an analyzer 7, and is detected by a detector 8.

[Problems to be Solved by the Invention] However, in such a conventional optical pickup, a large number of optical components are used, making the optical pickup large and heavy. Furthermore, since the laser beam passes through many optical components, there is a problem in that the light utilization efficiency is reduced due to absorption, reflection, etc.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems, and by adding a half-mirror function to the shaping prism, the number of parts used in the optical pickup can be reduced.
The objectives are to achieve faster access by making optical pickups smaller and lighter, to improve reading efficiency by increasing light usage efficiency, and to improve the performance of optical disk devices.

[Means for Solving the Problems] For this reason, the present invention includes a shaping prism that is disposed in the optical path from the semiconductor laser to the optical disk and has a shaping surface for shaping the Radhe light, so that the reflected light from the optical disk is By using an optical pickup characterized in that a detection section is arranged with respect to the shaping prism so that the prism is separated by the shaping surface and detected, it is possible to improve the performance of the optical disk device.

[Function] According to the configuration of the present invention, since the shaping surface of the shaping prism can shape the laser beam from the semiconductor laser and separate the reflected light from the optical disk, the number of optical components used is reduced, and the structure is small and lightweight. It becomes an optical pickup.

[Example] The details will be explained below with reference to FIG. 2 showing an example of the present invention. In the description, the same numbers will be given to the same parts as the conventional one.

In the figure, a laser beam emitted from a semiconductor laser 1 is collimated by a collimator lens 2, shaped by a shaping prism 9, focused by an objective lens 5, and irradiated onto an optical disk. The reflected light from the optical disk is made into parallel light by an objective lens 5, reflected and separated by a shaping surface of a shaping prism 9, and detected by a detector 8. The apex angle of the shaping prism 9 is determined by the shaping ratio of the laser beam, and the P polarization transmittance Tp, the S polarization transmittance TS, and
By appropriately selecting the polarization reflectance Rp, # and the SS light reflectance R8, the shaping prism can be given the function of a beam splitter that splits light.

Further, in the configuration shown in FIG. 2, by setting the transmittance and reflectance of the shaping prism to values close to TS-100% and Rp=100%, application to magneto-optical disks is also possible.

FIG. 3 shows the second embodiment, which is an example of application to a magneto-optical disk. The difference from the first embodiment is that the reflected light from the optical disk separated by the shaping prism 9 is transmitted through the analyzer 7 and detected by the detector 8. At this time, the transmittance and reflectance of the shaping prism 9 may be arbitrary values.

FIG. 4 shows the third embodiment, which is an example of application to a magneto-optical disk. This embodiment is an example applied to a differential type optical pickup. The reflected light from the magneto-optical disk separated by the shaping prism 9 is divided into two components, P-polarized light and S-polarized light, by a polarizing beam splitter 10 and detected by two detectors 11 and 12. Furthermore, in this embodiment, it is also possible to insert a λ/2 plate into the optical path between the shaping prism 9 and the polarizing beam splitter 10 to adjust the polarization direction of the reflected light.

FIG. 5 shows a modification of the shaping prism 9 used in the present invention. The shaping prism has two different refractive indexes of Is quality 14
and 15 to form a groove, and the boundary surface 13 between the two media serves as a shaping surface. It is also possible to replace the shaping prism made of this 2TS quality with the shaping prism of the above embodiment.

[Effects of the Invention] As described above, in the present invention, since the shaping prism has the function of a half mirror, the half mirror is not required, making it possible to make the optical pickup smaller and lighter, which improves high-speed access and light utilization efficiency. Improving reading ability,
This has the excellent effect of improving the performance of optical disk devices.

[Brief explanation of the drawing]

FIG. 1 is a conventional configuration diagram of an optical pickup for a magneto-optical disk, FIG. 2 is a configuration diagram of an optical pickup according to the present invention, and FIGS. 3 and 4 are diagrams showing other embodiments.
FIG. 3 is a diagram showing an optical pickup using a single detection method, and FIG. 4 is a diagram showing an optical pickup using a differential detection method. Moreover, FIG. 5 is a diagram showing a modification of the shaping prism used in the present invention. 1... Semiconductor laser, 2... Collimator lens, 3
゜9...Orthopedic prism, 4...Half mirror-15.
...Objective lens, 6...Disk, 7...Analyzer, 8.11 and 12...Detector, 10...
Polarizing beam splitter, 13...boundary surface.

Claims (1)

[Claims] 1. A semiconductor laser that irradiates an optical disk with laser light;
an optical pickup having a detection section for detecting reflected light from the disk, the optical pickup including a shaping prism having a shaping surface for shaping the laser beam, disposed in the optical path from the semiconductor laser to the optical disk; An optical pickup characterized in that a detection section is arranged with respect to the shaping prism so that reflected light from the shaping prism is separated by the shaping surface and detected. 2. The optical pickup according to claim 1, wherein the optical disk is a magneto-optical disk. 3. The optical pickup according to claim 1, wherein the shaping surface of the shaping prism is formed at an interface between two media having different refractive indexes.