JPS6113211A - Semiconductor laser beam synthesizing method - Google Patents

Abstract

PURPOSE:To obtain an optical beam having an approximately perfect circle- shaped section without using an optical system by synthesizing plural semiconductor laser beams so that axes of ellipticities of respective beam sections cross one another on a common spot at intervals of an approximately equal angle. CONSTITUTION:Optical beams emitted from, for example, four semiconductor lasers 11, 12, 13, and 14 are collimated to parallel beams 41, 42, 43, and 44 by collimator lenses 21, 22, 23, and 24 and are reflected on reflecting mirrors 31, 32, 33, and 34 and are made incident on a common galvanometer mirror 5. The galvanometer mirror 5 is turned back and forth in the direction of an arrow A to deflect parallel beams 41, 42, 43, and 44. Deflected parallel beams are converged on one spot S by a common converging lens 6. Respective axes P1, P2, P3, and P4 of ellipticities of sections of parallel beams 41, 42, 43, and 44 cross one another at intervals of an equal angle, and the section of the synthesized optical beam is an approximately perfect circle.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a semiconductor laser beam synthesis method for synthesizing laser beams emitted from a plurality of semiconductor lasers so that they overlap at a common spot. The present invention relates to a semiconductor laser beam combining method in which a shaped combined beam can be obtained.

(Technical Background and Prior Art of the Invention) Conventionally, light beam scanning devices that scan a light beam by deflecting it with an optical deflector have been widely put into practical use, for example, in various scanning recording devices, scanning reading devices, etc. . A semiconductor laser has conventionally been used as one of the means for generating a light beam in such an optical beam scanning device. This semiconductor laser is small compared to gas lasers, etc.
It has many advantages, such as being inexpensive, consuming little power, and allowing direct modulation by changing the drive current.

However, on the other hand, when this semiconductor laser is continuously oscillated, the current output is only 20 to 30 mW.
It is small in size and is therefore used in scanning recording devices that record on low-sensitivity recording materials (such as DRAW materials such as metal films and amorphous films), which require high-energy scanning light. It is extremely difficult.

In addition, certain fluorophores are exposed to radiation (X-rays, α-rays, β-rays,
When irradiated with γ-rays, ultraviolet rays, etc., a part of this radiation energy is accumulated in the phosphor, and when this phosphor is irradiated with excitation light such as visible light, the phosphor increases depending on the accumulated energy. is known to exhibit stimulated luminescence, and by using such a stimulable fluorophore, radiation image information of a subject such as a human body can be transferred to a stimulable fluorophore having a layer made of a stimulable fluorophore. record on a stimulable phosphor sheet, scan this stimulable phosphor sheet with excitation light such as a laser beam to generate stimulated luminescence light, read out the obtained stimulated luminescence light photoelectrically to obtain an image signal, The applicant has already proposed a radiation image information recording and reproducing system that outputs the radiation image of the subject as a visible image to a recording material such as a photographic light-sensitive material, CRT, etc. based on this image signal (Japanese Patent Laid-Open No. 55-12429 No. 55-1163
No. 40, No. 55-163472, No. 56-11395
No. 56-104645, etc.). In this system, the use of a light beam scanning device using a semiconductor laser has been considered in order to read the image information by scanning the stimulable phosphor sheet on which radiation image information has been stored and recorded. In order to stimulate the phosphor to emit light, it is necessary to irradiate the phosphor with excitation light of sufficiently high energy. It is extremely difficult to use it for reading image information.

Therefore, when using a semiconductor laser in an optical beam scanning device, in order to obtain a sufficiently high-energy scanning beam from a semiconductor laser with a low optical output as described above, multiple semiconductor lasers are used, and the laser emitted from these semiconductor lasers is It is conceivable to combine the beams so that they overlap at the scanning point.

On the other hand, in the above-mentioned light beam scanning device, it is desirable that the cross-sectional shape of the scanning beam be a perfect circle in order to substantially match the resolution in the main scanning direction and the sub-scanning direction. However, as is well known, a laser beam emitted from a semiconductor laser has different divergence angles in a direction parallel to and perpendicular to the pn junction surface of the semiconductor laser, and has an elliptical cross-sectional shape. Conventionally, when a light beam with a circular cross-section is required as described above, when using a semiconductor laser, the laser beam emitted from the semiconductor laser is It was shaped into a perfect circle.

However, when multiple semiconductor lasers are used to obtain a high-energy scanning beam as described above, it is necessary to use optical systems such as the prisms for the number of semiconductor lasers, which increases the size of the scanning device. This also increases the cost of the scanning device.

(Objective of the Invention) Therefore, the present invention aims to provide a method for synthesizing a plurality of semiconductor laser beams, which can obtain a light beam having a substantially circular cross section without using an optical system such as the above-mentioned prism. This is the purpose.

(Structure of the Invention) As described above, the semiconductor laser beam combining method of the present invention, when superimposing each laser beam having a circular cross section emitted from a plurality of semiconductor lasers at a common spot,
The present invention is characterized in that the laser beams are combined such that the inertial circular axes of the respective beam cross sections intersect with each other at approximately equal angular intervals on the common spot.

(Embodiments) Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 shows an apparatus for implementing the first embodiment method of the present invention. - As an example four semiconductor lasers 11.1
2.13.14 are arranged with their beam emission axes parallel to each other, and these semiconductor lasers 11.12.13.14
Collimator lenses 21, 22, 23 for each of
．． 24 and reflective mirrors 31, 32, 33, and 34 are provided. The light beam emitted from each semiconductor laser 11.12.13.14 is transmitted through the collimator lens 21.22.
．． Parallel beam 41.42.43.4 by 23.24
4, and this parallel beam 41.42.43.44 is reflected by the reflecting mirror 31.32.33.34 and enters the common galvanometer mirror 5.

The galvanometer mirror 5 reciprocates in the six directions of arrows in the figure and deflects the parallel beams 41, 42, 43, and 44.

The deflected parallel beams 41, 42, 43, 44 are focused into one spot S by a common focusing lens 6 and are each focused in this spot S. Therefore, if the surface to be scanned 7 is placed at a position where the spot S is irradiated, the surface to be scanned 7 will be exposed to high energy as the light beams emitted by the respective semiconductor lasers 11, 12, 13, and 14 are combined. arrow B by the scanning beam
scanned in the direction. Note that the surface to be scanned 7 is usually a flat surface, and therefore an fθ lens is used as the focusing lens 6.

Figure 2 shows four parallel beams 41 at the spot S.
．． 42, 43, and 44 are synthesized. As shown in FIG. 2, parallel beams 41.
42, 43, 44 each have a circular cross section, but each parallel beam 41, 42, 43, 44 has a circular axis P1, P2, P3, P4 at equal angular intervals (i.e., in this case are synthesized so that they intersect at 45° intervals). Therefore, the cross-sectional shape of the combined light beam is approximately circular, although there are some irregularities at the periphery.

In the above embodiment, the galvanometer mirror 5
The parallel beams 41, 42, 43, 44 emitted from the They may be arranged in a direction other than the above.

FIG. 3 shows an apparatus for implementing the second embodiment method of the present invention. In this device, three semiconductor lasers 11
．． 12, 13 and reflecting mirrors 31, 32, 33 are arranged so that their respective beam axes are concentrated at one spot S. In addition, each semiconductor laser 11. ,12.
Convergent beams 51, 52, 53 that focus the emitted light beams on the spot S for each of 13.
A focusing lens 61, 62, 63 is provided.

The focused beams 51, 52, 53 are deflected by the galvanometer mirror 5, and the spot S scans in a circular arc R. Therefore, in this case as well, the surface to be scanned 7 arranged along the arc R is
2.13 is a combination of high-energy light beams emitted by
- will be scanned by the scanning beam.

In this case as well, as shown in FIG.
By combining P2 and P3 so that they intersect with each other at approximately equiangular intervals (60° intervals in this case), the cross-sectional shape of the combined light beam can be made approximately circular.

The embodiment in which a light beam obtained by combining a plurality of semiconductor laser beams is scanned has been described above, but the present invention also provides a method for making the cross-sectional shape of the combined beam approximately circular even when the combined beam is not specifically scanned. applicable. Further, the number of semiconductor laser beams to be combined is not limited to four or three, and the larger the number of beams to be combined, the closer the cross-sectional shape of the combined beam becomes to a perfect circle.

(Effects of the Invention) As explained in detail above, according to the semiconductor laser beam combining method of the present invention, semiconductor laser beams with low optical output can be combined to obtain a high-energy optical beam, and optical Since the light beam can be made to have a substantially circular cross section without using a system, it becomes possible to downsize the device using the composite beam and to form it at low cost.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an apparatus for implementing a semiconductor laser beam combining method according to a first practical IM aspect of the present invention; FIG. 2 is an explanatory diagram showing a cross-sectional shape of a light beam combined by the above method; The figure is a schematic perspective view showing an apparatus for carrying out the semiconductor laser beam combining method according to the second embodiment of the present invention, and FIG. be. 6...Focusing lens

Claims (1)

[Claims] In a semiconductor laser beam combining method in which laser beams each having a circular cross section emitted from a plurality of semiconductor lasers are superimposed at a common spot, the laser beams are combined such that the circular axis of each beam cross section is on the common spot. A semiconductor laser beam combining method characterized by combining semiconductor laser beams so that they intersect with each other at approximately equal angular intervals.