JPS6258214A - Optical beam scanner - Google Patents

Abstract

PURPOSE:To properly perform corrections for surface tilting and wobbling, by making plural optical beams incident on a cylindrical lens by arranging them in such a way that the major axis of the cross section of each beam can almost coincide with the direction of the generating line of the cylindrical lens and two or more optical beams can be arranged so that the minor axes of the cross sections of these optical beams can almost be aligned in one line. CONSTITUTION:Optical beams 41-44 passed through collimater lenses 21-24 are made incident on the 1st cylindrical lens 5 under a condition where they are arranged in such a way that the major axis of the cross section of each beam can almost coincide with the direction of the generating line X-X of the lens 5 and, at the same time, the minor axis of the cross section can almost be aligned in one line. Therefore, the beam flux composed of these optical beams 41-44 does not pass through the peripheral part of the lens 5 which is far from the center and is able to form an ideal line image without receiving any influences of the aberration of the lens 5. On the other side, the line image has a length which is the same as the width of the beams made incident on the 1st cylindrical lens 5 in the direction of the generating line of the lens 5 since the optical beams 41-44 are arranged in the direction of the generating line. Therefore, a relatively small-sized one can be used as the rotating polygon mirror 6 of this device.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a light beam scanning device that scans a light beam using a mechanical optical deflector that reflects and deflects the light beam using a reflective surface. This is to punish the optical beam scanning fiw that allows a high-energy scanning beam to be obtained while using.

(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, and the like. One of the means for generating a light beam in such a light beam scanning device
As one example, semiconductor lasers have been conventionally used. This semiconductor laser has many advantages, such as being smaller, cheaper, and consumes less power than gas lasers, and can be directly modulated 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.
A light beam scanning device that is small and therefore requires high-energy scanning light, such as the recording 44F1 (with low impression)
It is extremely difficult to use it in a scanning recording device that records on a metal film, an amorphous film, etc. Also, some types of phosphors are exposed to radiation (X-rays, α-rays, β-rays, γ-rays,
When irradiated with 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 is exhausted according to the accumulated energy. It is known that such a stimulable phosphor does not emit light, and by using such a stimulable phosphor, radiation image information of a human body, etc. Recording is performed on a stimulable phosphor sheet, and the stimulable phosphor sheet is scanned with excitation light such as a laser beam to generate stimulated luminescent light, and the resulting stimulated luminescent light is read photoelectrically to form an image. The applicant has already proposed a radiation image information recording and reproducing system that obtains a signal and outputs it as a visible image to a recording material such as a photosensitive material, a CRT, etc. based on this image signal (Japanese Patent Laid-Open No. 55
-12429, 55-116340, 55-1
No. 63472, No. 56-11395, No. 56-104
645 etc.).

In this system, it has been considered to use a light beam scanning device using a semiconductor laser to scan a stimulable phosphor sheet on which radiation image information is stored and read the image information. However, in order to stimulate a stimulable phosphor to emit light, it is necessary to irradiate the phosphor with excitation light of sufficiently high energy. It is also difficult to use it for reading image information in an image information recording and reproducing system.

In view of the above circumstances, the present applicant has developed a plurality of semiconductor lasers, a collimator lens that converts the light beams emitted from these semiconductor lasers into parallel beams, and a common focusing optical system that focuses the plurality of light beams onto a common spot. system and -F
We proposed a light beam scanning device consisting of a common light deflector that deflects a plurality of light beams (Japanese Patent Application No. 76889/1989).
@). According to such a light beam scanning device, a scanning beam with sufficiently high energy can be obtained even if a semiconductor laser with low optical output is used as the light beam generating means.

As the above-mentioned optical deflector, a mechanical optical deflector that reflects and deflects a light beam in the anti-tJJ direction, such as a galvanometer mirror or a polygon mirror (rotating polygon mirror), is often used. When using this type of mechanical optical deflector,
Scanning deviations may occur due to surface inclination or wobbling of the mirror surface, but generally such scanning deviations are caused by surface inclinations with cylindrical lenses, as shown in the above-mentioned Japanese Patent Application No. 59-76889. This can be solved using a correction optical system.

However, as the number of light beams passing through the cylindrical lens increases, some of the light beams will pass through the periphery of the cylindrical lens. In this way, the light beam passing through the periphery of the cylindrical lens becomes susceptible to the aberrations of the cylindrical lens,
It becomes difficult to form an ideal line image on the mirror, that is, a line image that is not curved and is sufficiently thin. In order to eliminate this problem, if the optical beams are arranged so that all the light beams are incident on the central part on the generatrix of the cylindrical lens, the line image tends to be long in this case, and a mirror with a large mukai area is A problem arises in that a large optical deflector is required.

(Object of the Invention) Therefore, the present invention is capable of correctly performing the above-mentioned surface tilt correction and wobbling correction by forming an ideal line image of a light beam on the mirror of a mechanical optical deflector. An object of the present invention is to provide a laser beam combining type optical beam scanning device that can use a type optical deflector.

(Structure of the Invention) In the optical beam scanning device of the present invention, the laser beam emitted from the semiconductor laser has different divergence angles in a direction parallel to and a direction perpendicular to the pn junction surface of the semiconductor laser, and its cross-sectional shape is This was done by focusing on the circular shape, and the above-mentioned J, Una plural semiconductor lasers,
] In a light beam scanning device consisting of a remeter 1 nons, a common focusing optical system, a common mechanical optical deflector, and a surface tilt correction optical system having a cylindrical 1 nons, a plurality of light beams are The long axis of the cross section substantially coincides with the generatrix direction of the cylindrical lens, and two or more light beams of the plurality of light beams are arranged so that the short axis of the cross section is substantially aligned with the - line, thereby forming the cylindrical lens. It is characterized in that it is made incident on U.

(Embodiment) Hereinafter, the present invention will be described based on the example 1 AIB shown in the drawings.
Explain to lll.

FIG. 1 shows an actual IM mode of the optical beam scanning device 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
For each of the "remator lenses 21.22.2
3.24 and reflective mirrors 31.32.33.34 are provided. The lep beam emitted from each semiconductor laser 11, 12, 13, 14 is
1.22.23.24 parallel beam 41.42.
43.44 and these light beams 41.42.43
．． The beams 44 are reflected by the reflecting mirrors 31, 32, 33, and 34, and the beams are closely spaced to form a single beam bundle, which passes through the first cylindrical lens 5 to a common rotating polygon mirror (polygon mirror). ) 6.

The rotating polygon mirror 6 rotates in the vertical direction in the figure and deflects the 1-light distribution beam 41, 42, 43, 44 in the direction of arrow B.

The deflected light beams 41, 42, 43, 44 are focused on one spot S on the scanned surface 9 by the converging lens 7 and the second cylindrical lens 8, and each focused. Therefore, the surface to be scanned 9 is connected to each semiconductor laser 11 .
The light beams emitted by 12, 13, and 14 are combined and scanned in the direction of arrow B by a high-energy scanning beam. Note that the surface to be scanned 9 is usually a flat surface, and therefore an fθ lens is used as the focusing lens 7.

Here, the plurality of parallel light beams 41 to 44 are as follows:
The first cylindrical lens 5 focuses the image only in the vertical direction in the figure, and the second cylindrical lens 8 focuses the image at a certain vertical position on the scanned surface 9.
The spoiler hS is no longer displaced in a direction perpendicular to the scanning direction B. Therefore, the rotating polygon mirror 6 has a tilted surface, and the light beam 4 reflected by the rotating polygon 116
Even if the beams 1 to 44 are displaced in a wave manner with respect to the normal light deflection direction, the spot S does not move vertically on the scanned surface 〇, and scanning deviation can be corrected.

As is well known, the laser beams emitted from the semiconductor lasers 11 to 14 have different divergence angles in the direction parallel to and perpendicular to the pn junction surfaces of the semiconductor lasers 11 to 14, and the beam cross-sectional shape is circular. However, as shown in detail in FIG. 2, the light beams 41 to 44 that have passed through the collimator lenses 21 to 24 in the light beam scanning device have their long axes in cross section aligned with the first cylindrical lens 5. The light beams are arranged in a line of 10- to be incident on the first cylindrical lens 5 so that they substantially coincide with the generatrix xx direction and have their short axes substantially aligned with the - line. Therefore, the beam bundle consisting of these light beams 41 to 44 does not pass through the periphery far from the center of this first cylindrical lens 5, and therefore
An ideal line image is created without being significantly affected by aberrations. On the other hand, since the light beams 41 to 44 are aligned in the direction of the generatrix of the first cylindrical lens 5, the above-mentioned line image is the direction of the generatrix of the cylindrical lens 5 of the beam incident on the first cylindrical lens 5. The length is the same as the width of the rotating polygon mirror 6, so a relatively small rotating polygon mirror 6 can be used.

In the embodiment described above, the rotating polygon mirror 6 is used as the mechanical optical deflector, but a known galvanometer mirror may also be used as the mechanical optical deflector. In this case as well, by using the first and second cylindrical lenses 5.8, it is possible to correct scanning deviations due to wobbling of the galvanometer mirror.

Further, the cylindrical lens 8 described in -F description 2 may be arranged between the rotating polygon mirror 6 and the focusing lens 7, or the cylindrical lens 8 described in -F description 2 may be arranged between the first and second cylindrical lenses as described in Japanese Patent Publication No. 58-8. It may also be placed between the rotating polygon 16 and the focusing lens 7.

Furthermore, the number of light beams to be combined is also 4 in the above embodiment.
The light beam is not limited to a book, and two or more light beams may be combined. Here, when there are many light beams to be combined, as shown in Figure 3, a plurality of light beam arrays are arranged so that the short axis direction of the light beam cross section is approximately aligned with the - line, and the long axis direction is They may be combined in a plurality of rows (in the generatrix XX direction of the cylindrical lens 5).

(Effect of the invention in Song Dynasty) As explained in detail above, the light beam scanning device of the present invention has the following features:
Although a semiconductor laser with a low optical output is used as a light beam generating means, a high-energy scanning beam can be obtained, so for example, as mentioned above, a high-energy scanning beam is required, and recording on RAW material or storage is difficult. It can also be used to read radiation image information from a phosphor sheet, and by taking advantage of the many features of the semiconductor laser described above, it can be used in a wide range of fields. Moreover, in the light beam scanning device of the present invention, since the plurality of light beams form an immediate line image on the mirror of the optical deflector, the tilting of the surface of the mirror and wobbling can be reliably corrected. As a result, scanning accuracy is improved. Further, although the light beam scanning device of the present invention combines a plurality of light beams, it can use a relatively small optical deflector and can be formed at low cost.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing one embodiment of the light beam scanning device of the present invention, FIG. 2 is a schematic diagram showing how the light beams combined in the above-mentioned actual ms-like device are arranged, and FIG. FIG. 2 is a schematic diagram showing how light beams are arranged. 5.8...Cylindrical lens 6...Rotating polygon 1 7...Focusing lens 9...
・Scanned surface 11.12.13.14...Semiconductor laser 21.22
．． 23.24...Collimator lens 41.42.43
．． 44...Light beam Figure 3

Claims (1)

[Claims] a plurality of semiconductor lasers, a collimator lens that converts each of the light beams having an elliptical cross section emitted from these semiconductor lasers into parallel lights, a common focusing optical system that focuses the plurality of light beams onto a common spot; In a light beam scanning device comprising a common mechanical optical deflector that deflects a plurality of light beams, a surface tilt correction optical system having a cylindrical lens is provided, and the plurality of light beams incident on the cylindrical lens are The long axis of the cross section of each beam substantially coincides with the generatrix direction of the cylindrical lens, and two or more light beams among the plurality of light beams are arranged so that the short axes of the cross sections are substantially aligned. A light beam scanning device.