JPS6350921A - Optical head optical axis adjustment device - Google Patents

Abstract

PURPOSE:To attain the coincidence between an optical axis and a laser in a direction of intensity, and to reduce the loss of the laser, by providing a mechanism capable of moving a prism which shapes the wave front of a light beam in a direction of X, in the direction of X, and of rotating it within X-Z plane. CONSTITUTION:When aberration of theta deg. is generated in the direction of the maximum intensity of a semiconductor laser 1, the beam of a semiconductor is made incident on the center part of a polarizing prism by moving a shaping prism system 3 by psi deg. in a rotating direction. At such a time, the light beam emitted from the shaping prism system 3 is jogged only by an amount of (i) from the center part of the shaping prism system 3 to the X direction, and the coincidence between the optical axis and the laser in the direction of the maximum intensity can be obtained, thereby, it is possible to prolong the service life of the semiconductor laser.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention focuses and irradiates a light flux emitted by an optical head of an optical video disc, compact disc, recording/reproducing optical disc, etc. onto the disc, and uses the reflected or transmitted light to The present invention relates to an optical axis adjustment device for an optical head that records or reproduces signals.

Page 2 Prior Art An example of a conventional optical axis adjustment device will be described below with reference to the drawings.

FIG. 5 shows an example of an optical system of an optical head.

In FIG. 5, the laser beam emitted from the semiconductor laser element 1 passes through the collimating lens 2, the shaping prism system 3, the polarizing beam splitter 4, the % wavelength plate 5, and the objective lens 6, and the light reflected onto the disk is reflected by the single lens 8. After passing through and entering the detector 9, it is converted into an electrical signal.

In FIGS. 9 and 10, the optical axis of the optical head configured as described above is aligned using the prism 4 and Install shaping prism system 3.

Next, the semiconductor laser 1 is slightly moved in the X and Y directions so as to match the optical axis, and the light beam emitted from the semiconductor laser is converted into a He
-No The light beam was aligned with the optical axis.

Problems to be Solved by the Invention In the ideal beam direction as shown in Fig. 7, the beam is emitted from the center of the beam splitter 4 as shown in the figure on page 23 without any problem, but as shown in Fig. 8. The beam direction of the laser has an angular variation of 2° to 3°, and when the optical axis is aligned using a semiconductor laser with this angular deviation, the center of the intensity distribution of the beam emitted from the semiconductor laser is away from the optical axis. As a result, the optical axis and the center of the light distribution shift, resulting in loss of laser power.

Therefore, there are problems in that a larger output is required, which may shorten the life of the semiconductor laser.

In view of the above-mentioned problems, the present invention provides an effective optical axis adjustment device for reducing loss even in a semiconductor laser having an angular deviation of the emitted beam.

Means for Solving the Problems In order to solve the above-mentioned problems, the optical axis adjusting device for an optical head according to the present invention adjusts the light beam emitted from the optical system by moving a shaping prism system that shapes a radiation light source. It has a configuration that matches the axis and the distribution of light.

Effects of the present invention With the above-described configuration, even in an optical system where the optical axis and the center of the light distribution are misaligned, the optical axis and the center of the light distribution can be aligned by slight movement of the shaping prism, which reduces the loss of the semiconductor laser. The lifetime of the laser can also be extended.

Embodiment Hereinafter, an optical head optical axis adjusting device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a basic configuration diagram of an optical head optical axis adjustment device in an embodiment of the present invention.

In Figure 1, 1 is a semiconductor laser as a light emitting source, 2 is a collimating lens that converts the laser beam into approximately parallel light, and 3 is a collimating lens that changes the laser beam pattern from an ellipse (see Figure 6) to an approximately circular shape to eliminate astigmatism. This is a shaping prism that corrects The operation of the optical head optical axis adjustment device configured as described above will be explained with reference to FIGS. 1, 2, 3, and 4.

FIG. 2 represents a plan view of an embodiment according to the invention. Normally, when there is no deviation in the direction of the maximum intensity of the semiconductor laser 1, the beam passes through the collimating lens 2 and then the five-page prism system 3 and enters the center of the polarizing beam splitter. In Fig. 3, if the maximum intensity direction of the semiconductor laser 1 is shifted by 00, the collimating lens 2
The beam is incident on the shaping prism at an angle shifted by 00, and is also incident on the shaping prism with a shift. The beam exiting the shaping prism enters the polarizing beam splitter in a shifted state. In this case, the optical axis and the center of the intensity of the light beam do not coincide.

In FIG. 4, in the optical axis adjustment device of the present invention, the beam of the semiconductor laser with the θ0 angle deviation is adjusted to 90 degrees by the shaping prism system.
The beam is moved in the rotational direction and made incident on the center of the polarizing prism. At that time, the light beam emitted from the shaping prism system is shifted by i in the X direction from the center of the shaping prism system, so the shaping prism system can be slightly moved by 1 in the X direction to align the optical axis and the maximum intensity direction of the laser. The life of the semiconductor laser can be extended because the efficiency of the laser does not deteriorate and a larger output is not required.

Effects of the Invention As described above, the present invention provides a mechanism that allows the prism that shapes the wavefront of the light beam into 6 pages in the X direction to be movable in the X direction and rotatable in the Even in an optical system where the intensity direction of the laser beam is shifted, the optical axis and the laser intensity direction can be made to match, reducing laser loss and increasing the lifespan of the semiconductor laser since a larger output is not required.

[Brief Description of the Drawings] Fig. 1 is an exploded perspective view showing the basic configuration of the optical head optical axis adjusting device in an embodiment of the present invention, and Fig. 2 shows the optical axis when there is no direction shift in the laser beam. Fig. 3 is a plan view of the optical system showing the optical axis when a 00 degree deviation occurs in the laser beam direction, and Fig. 4 shows the optical system in which the laser beam direction is deviated. A fifth plan view of the optical system showing the optical axis when the optical axis adjustment device of the present invention is implemented.
The figure is a cross-sectional view showing an example of the optical system of a conventional optical head.
Figure 6 is a schematic diagram showing the general beam shape of a semiconductor laser, Figure 7 is a schematic diagram showing on page 7 that the intensity distribution of the output beam of the semiconductor laser matches the optical axis direction, and Figure 8 is a schematic diagram showing that the intensity distribution of the output beam of the semiconductor laser matches the optical axis direction. A schematic diagram showing that the intensity distribution of the output beam of a semiconductor laser is deviated from the optical axis direction,
FIG. 9 is a perspective view showing optical axis adjustment using a He--Ne laser, and FIG. 1Q is a perspective view showing optical axis adjustment by finely moving a conventional semiconductor laser. 1... Semiconductor laser, 2... Collimating lens, 3... Shaping prism system, 4...
...Polarizing beam splitter - 15...% wavelength plate, 6...Objective lens, 7...Optical disk, 8...Single lens, 9... ...Detector, 1o...He-Ne laser reference light source,
11... Intensity distribution direction of semiconductor laser beam,
12... Optical bench case, 13... Optical axis of optical system. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Diagram Nine-dimensional case

Claims (1)

[Claims] A radiation light source with astigmatism, a collimating system that converts this radiation light source into approximately parallel light, a prism system that shapes the wavefront of the light beam emitted from this collimating system, and a prism system that aligns the optical axis direction with the Z axis. an optical head comprising a mechanism capable of shaping the wavefront of the light beam emitted from the collimating system in the X direction in an orthogonal coordinate system, and a mechanism capable of making the prism movable in the X direction and rotatable in the XZ plane; Adjustment device.