JPS62264453A - Optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain the conversion of a circle beam to a parallel circular beam, by positioning the first almost cylindrical lens, and the second almost cylindrical lens on the optical axis of divergent light, and positioning respective focus on the emitting point of a semiconductor laser. CONSTITUTION:First of all, the divergent light whose cross-sectional shape is formed in a circle from a semiconductor laser 1 is made incident on a beam arranging element 8. The almost cylindrical light refracting plane A of the beam arranging element has a focus distance of fA, and a light beam shown in view Q is converted to a parallel light beam by coinciding a focus position with the emitting point of the semiconductor laser 1. An almost cylindrical light refracting plane B to which the light beam is made incident has a focus distance of fB, and the light beam shown in view P is converted to the parallel light beam by coinciding the focus position with the emitting point of the semiconductor laser 1. The circular beam having a requested diameter can be obtained by using the beam arranging element on which the fA and the fB are set at specific values, corresponding to beam diameter ratios on the parallel side and the vertical side of the divergent light.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is an optical system that can be used in all systems including equipment for recording or reproducing information, such as external memory for computers, audio recording/playback systems, video recording/playback systems, etc. The present invention relates to a recording/reproducing device.

Conventional Technology The modern era is called the information age, and the technology development of high-density, large-capacity memory, which forms the core of this age, is actively being carried out.

In addition to the above-mentioned high density and large capacity, the capabilities required of memory include high reliability and high speed access, and optical disk memory is attracting the most attention as a device that satisfies all of these requirements. An optical disk memory is a device that optically records information on a recording medium, and recently, a lot of research has been conducted on magneto-optical disks that can also erase recorded information.

Semiconductor lasers are mainly used as light sources for optical disk memories.

FIG. 3 shows the entire far-field image of the semiconductor laser and the divergent light from the semiconductor laser. In FIG. 3, 1 is a semiconductor laser.

The semiconductor laser 1 emits light differently in a direction parallel to and perpendicular to the laser chip bonding surface.

That is, the far-field image of the light emitted from the semiconductor laser 1 is elliptical. If the light from this semiconductor laser 1 is focused using a normal optical system, the shape of the light spot will also become an ellipse. In order to avoid this, in the playback-only optical system for optical digital audio discs, a collimating lens with a small numerical aperture (HA) is used, that is, only the central part of the elliptical beam of the semiconductor laser 1 is used, and the other parts are By throwing away a circular light spot is obtained on the disk. However, in a recording/reproducing optical system using a semiconductor laser, the above-mentioned method is disadvantageous because the optical power utilization efficiency becomes low. Therefore, in the past, methods such as those described below have been used.

Hereinafter, a conventional optical recording/reproducing apparatus as described above will be explained with reference to the drawings.

FIG. 4 shows an example of a conventional optical recording/reproducing device. In FIG. 4, 1 is a semiconductor laser, 2 is a collimating lens, 3 is a concave cylindrical lens, and 4 is a convex cylindrical lens.

Figure 4a is a view in the direction of the P arrow in Figure 3, that is, the side parallel to the semiconductor laser chip bonding direction, and b is the perpendicular side, which is a view in the direction of the Q arrow in Figure 3, that is, rotated 90 degrees around the optical axis from Figure 4a. It is a figure showing a state.

The operation of an example of the conventional optical recording/reproducing apparatus configured as described above will be explained below.

The light from the semiconductor laser 1 is made into parallel light by the collimating lens 2, but the cross-sectional shape of the beam here is an ellipse. By passing through the concave cylindrical lens 3 and the convex cylindrical lens 4, only the parallel side of the fourth national radio is expanded and becomes a circular beam.

FIG. 5a shows a second example of a conventional optical recording/reproducing device, and FIGS. 5 and 5c show cross sections taken along line X-X and Y-Y in FIG. 5a, respectively. In FIG. 6, 1 is a semiconductor laser, 2 is a collimating lens, and 5 is a prism. The operation of the second example of the conventional optical recording/reproducing apparatus configured as described above will be explained below.

Similar to FIG. 4, the cross-sectional shape of the parallel light produced by the collimating lens 2 is an ellipse. (X-X line cross section) The prism 5 on which this parallel light enters has a triangular prism shape, and is expanded by refracting and transmitting only the side parallel to the semiconductor laser chip bonding direction from the collimating lens 2, and converting it into a circular beam. ing.

(Y-Y line cross section) Problems to be Solved by the Invention However, in the conventional configuration shown in FIG. Three optical elements are required, and the position adjustment of each is complicated. Furthermore, in the conventional configuration shown in FIG. 5, the collimating lens 2. Since a parallel circular beam can be obtained with the two optical elements of the prism 5, the configuration and adjustment are simple, but since the optical axis is tilted with the prism 6 as the boundary, the shape of the optical system housing becomes complicated. It had the problem of increasing its size.

In view of the above-mentioned problems, the present invention provides an optical recording and reproducing device that can obtain a parallel circular beam whose optical axis does not tilt with respect to the diverging optical axis of a semiconductor laser through simple configuration and adjustment. .

Means for Solving the Problems In order to achieve this object, the optical recording/reproducing apparatus of the present invention includes a semiconductor laser and a diverging beam located on the optical axis of the semiconductor laser in the direction of joining the semiconductor laser chips. At least one optical element having substantially cylindrical light refractive surfaces on the vertical side and the parallel side is provided, and the different focal points of the respective light refractive surfaces are positioned at the light emitting point of the semiconductor laser. ing.

According to the present invention, with this configuration, the diverging light from the semiconductor laser is converted into parallel light only on the side perpendicular to the semiconductor laser chip bonding direction by the first substantially cylindrical light refracting surface, and the diverging light from the semiconductor laser is converted into parallel light by the second substantially cylindrical light refracting surface. Only the side parallel to the joining direction is converted into parallel light.

Therefore, with a simple configuration and adjustment that does not require a collimating lens, it is possible to convert an elliptical beam, which is the emission characteristic of a semiconductor laser, into a parallel circular beam without the optical axis tilting to the diverging optical axis of the semiconductor laser. .

EXAMPLE An example of the present invention will be described below with reference to the drawings. FIG. 1 shows an optical recording/reproducing apparatus according to an embodiment of the present invention. Figure 1a is a view in the direction of arrow P in Figure 3, that is, the side parallel to the semiconductor laser chip bonding direction,
The figure shows the vertical side and is a view taken in the direction of the Q arrow in FIG. 3, that is, a view obtained by rotating 90° from FIG. 1a around the optical axis. In FIG. 1, 1 is a semiconductor laser, 6 is a substantially cylindrical lens, and 7 is a substantially cylindrical lens B.

Regarding the optical recording and reproducing device configured as above,
The operation will be explained below.

First, diverging light having an elliptical cross-sectional shape (see FIG. 3) from the semiconductor laser 1 enters the substantially cylindrical lens A6.

The substantially cylindrical lens A6 has a convex refracting surface in a direction perpendicular to the semiconductor laser chip bonding direction of the diverging light of the semiconductor laser, has a focal length f, and has a focal position that is aligned with the emission light of the semiconductor laser. If the laser beam is aligned with the beam point, the incident divergent light acts only on the side perpendicular to the bonding direction of the semiconductor laser chip, as shown in FIG. 1, and the side perpendicular to the bonding direction is converted into a parallel light beam. Due to this action, the diameter of the light beam in the Q arrow view increases,
becomes.

This light beam enters the substantially cylindrical lens BT, which has a convex refraction [1] on the side parallel to the semiconductor laser chip bonding direction of the diverging light of the semiconductor laser, and has a focal length f. If the focal point is aligned with the light emitting point of the semiconductor laser, as shown in Figure 1a, it will act on the light beam only on the side parallel to the bonding direction of the semiconductor laser chip, and will not act parallel to the side parallel to the bonding direction. Convert into a beam of light. This action increases the diameter of the light beam in the P arrow view.

becomes. In the far-field pattern shown in FIG. 3, if f and fB in FIG. Do) and M
B Desired diameter. Can you get parallel circular beams?

Note that fA and f have different values.

As described above, according to this embodiment, by providing two substantially cylindrical lenses that are located on the optical axis of the diverging light of the semiconductor laser and have the same focal position, a simple method that does not require a collimating lens is achieved. With this configuration, it is possible to obtain a parallel circular beam with a desired diameter and whose optical axis is not tilted with respect to the diverging optical axis of the semiconductor laser.

Regarding the adjustment, parallel light can be achieved in the Q arrow view by adjusting only the approximately cylindrical lens B, and P can be achieved by adjusting only the approximately cylindrical lens B.
Since it is sufficient to achieve parallel light in the arrow view, this can be achieved relatively easily.

Embodiments of the pond of the present invention will be described below with reference to the drawings. FIG. 2 shows an optical recording/reproducing apparatus according to another embodiment of the present invention.

FIGS. 2a and 2b are a view along the P arrow and a view along the Q arrow of FIG. 3, similar to FIG. 1.

In FIG. 2, 1 is a semiconductor laser, and 8 is a beam shaping element having two different approximately cylindrical light refracting surfaces.

Regarding the optical recording and reproducing device configured as above,
The operation will be explained below.

First, the diverging light having an elliptical cross-sectional shape from the semiconductor laser 1 (see FIG. 3) enters the beam shaping element 8. The beam shaping element has a substantially cylindrical light refractive surface and has a focal length of fA. By aligning the focal point position with the light emitting point of the semiconductor laser 1, the light beam in the Q arrow view is converted into a parallel light beam.

The approximately cylindrical light refractive surface B on which this light beam enters has a focal length of f.

If the focal position is made to coincide with the light emitting point of the semiconductor laser 1, the light beam in the P arrow view is deflected into a parallel light beam. In the far-field image shown in Fig. 3, depending on the beam diameter ratio between the parallel side and the perpendicular side of the diverging light, f and f in Fig. 2
By using a beam shaping element with B-m set to a specific value, it is possible to obtain a parallel circular beam of the desired diameter.

As described above, according to this embodiment, one optical fiber is located on the optical axis of the diverging light of the semiconductor laser and has two different substantially cylindrical light refractive surfaces with different focal points located at the light emitting point of the semiconductor laser. By providing a beam shaping element of A circular beam with parallel diameters can be obtained. Furthermore, since it is a single element, adjustment is easy and stability after adjustment is excellent. As described above, the overall shape of the optical system can be made smaller and simpler.

Effects of the Invention The present invention provides a first substantially cylindrical lens having a convex refractive surface on the side perpendicular to the junction surface of the semiconductor laser tip and a second lens having a convex refraction surface on the side parallel to the junction surface of the semiconductor laser and the divergent light of the semiconductor laser. The two substantially cylindrical lenses have different focal positions, and each focal point is located at the light emitting point of the semiconductor laser, resulting in a simple configuration that does not require a collimating lens. Thus, it is possible to obtain a parallel circular beam with a desired diameter and whose optical axis is not tilted with respect to the diverging optical axis of the semiconductor laser. Therefore, compared to conventional optical systems, it can be made smaller and simpler. However, since the two substantially cylindrical lenses are made into one beam shaping element having two different substantially cylindrical light refractive surfaces whose different focal points are located at the light emitting point of the semiconductor laser, adjustment is easy. This makes it possible to realize an excellent optical recording/reproducing device that can obtain the effect of increasing subsequent stability.

[Brief explanation of drawings]

1A and 1B are block diagrams showing an optical recording and reproducing apparatus in an embodiment of the present invention, FIGS. 2A and 2B are block diagrams showing an optical recording and reproducing apparatus in an embodiment of the present invention, and FIGS. Figure 3 is a perspective view showing a semiconductor laser and a far-field image of divergent light from the semiconductor laser, Figures 4a and b are block diagrams showing a conventional optical recording/reproducing device, and Figure 5a is a conventional optical recording. A configuration diagram showing a second example of the reproduction device, FIG. 6 is a sectional view taken along the line X-X of the same,
FIG. 5C is a sectional view taken along the line X--X. 1... Semiconductor laser, 2... Collimating lens, 6... Prism, 6... Approximately the same cylindrical lens, 7... Approximately cylindrical shaped lens B, 8.
...beam shaping element. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 1 - Straight shoulders 1

Claims (2)

[Claims] (1) a semiconductor laser, a first substantially cylindrical lens having a convex refractive surface in a direction perpendicular to the semiconductor laser chip bonding direction of the semiconductor laser, and a first substantially cylindrical lens convex in a direction parallel to the semiconductor laser chip bonding direction; a second substantially cylindrical lens having a refractive surface, the first substantially cylindrical lens and the second substantially cylindrical lens are located on the optical axis of the diverging light, and each focal point is located on the optical axis of the diverging light. An optical recording/reproducing device characterized in that it is located at the light emitting point of a laser. (2) The optical recording according to claim 1, wherein the first substantially cylindrical lens and the second substantially cylindrical lens are formed on both end surfaces of one beam shaping element. playback device.