JPH01125887A - Multi-laser beam source device - Google Patents

Abstract

PURPOSE:To enable laser beams to be composed together into a single beam at a required position by a method wherein the laser beams different from each other in wavelength are made to be composed together through a prism provided with a wavelength dispersion property. CONSTITUTION:Laser beams 2, 2', and 2'' are made to penetrate an incidence lens 6 to be parallel with each other and incident on a prism 7 from directions slightly different from each other. The prism 7 is previously selected from prisms which are provided with a wavelength dispersion property that enables the prism to project three beams which are different from each other in wavelength and incident on from directions slightly different from each other respectively onto the same optical path. The laser beams 2, 2', and 2'' which penetrate the prism 7 are composed into a single beam, which is incident on a galvanometer mirror 8 provided onto the optical path. Therefore, the laser beams 2, 2', and 2'' are made to be equal to each other with regard to the condition under which these beams are reflected by the galvanometer mirror 8, so that such a trouble as the reflective condition is made to varies corresponding to each beam due to the surface accuracy of the galvanometer reflective face can be eliminated. By these process, all beams are made to be focused on a convergent point P and an accurate composition of wave can be realized.

Description

Detailed Description of the Invention (Field of the Invention) The present invention relates to a multi-laser light source device that combines low-power laser beams emitted from laser light sources such as semiconductor lasers to obtain a high-power laser beam, and particularly relates to a multi-laser light source device that obtains a high-power laser beam by combining low-power laser beams emitted from laser light sources such as semiconductor lasers. relates to a multi-laser light source device that can improve the accuracy of the above-mentioned multiplexing.

(Prior Art) As is well known, optical scanning devices that scan a laser beam by deflecting it with an optical deflector are widely used in, for example, various scanning recording devices, scanning reading devices, etc. In scanning devices, for example, in order to speed up reading and recording, it is being considered to combine a plurality of laser beams and use them as scanning light. This multiplexing of laser beams is particularly required when the laser light source is a semiconductor laser. In other words, compared to gas lasers, semiconductor lasers are smaller, cheaper, consume less power, and can be directly modulated by changing the drive current.
Although it has many advantages, the current output is small at 20 to 3 HLw when continuous oscillation is used, and therefore it is difficult to use a light beam scanning device that requires high-energy scanning light, such as recording materials with low sensitivity (metallic). It is extremely difficult to use it in a scanning recording device that records on DRA tube materials such as films, amorphous films, etc.).

Also, some types of phosphors are exposed to radiation (X-rays, α-rays.

When irradiated with beta rays, gamma rays, electron beams, ultraviolet rays, etc., some of this radiation energy is accumulated in the phosphor, and when this phosphor is irradiated with excitation light such as visible light, the accumulated energy It is known that stimulable phosphors exhibit stimulated luminescence, and by using such stimulable phosphors, radiation image information of subjects such as the human body can be transferred to stimulable phosphors that have a layer made of stimulable phosphors. This 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 obtain an image signal. The present applicant has already proposed a radiation image information recording and reproducing system that outputs a radiation image of a subject as a visible image to a recording material such as a photographic light-sensitive material, a CRT, etc. based on an image signal (Japanese Patent Laid-Open No. 12429/1989). , No. 55-118340, No. 55-183472, No. 5
B-11395, 5B-104645, etc.).

In this system, an optical scanning device using a semiconductor laser is considered to be used to scan the stimulable phosphor sheet on which radiation image information is stored and read the image information. In order to read a sheet at high speed, it is necessary to irradiate the sheet with excitation light of sufficiently high energy. Therefore, the optical scanning device using the semiconductor laser is used for reading image information in this radiation image information recording and reproducing system. It is also extremely difficult to use.

Therefore, as mentioned above, in order to obtain a sufficiently high-energy scanning beam from a semiconductor laser etc. with low optical output, it is necessary to use multiple laser light sources and combine the laser beams emitted from these laser light sources into one beam. desirable.

In order to combine laser beams emitted from multiple laser light sources into a single laser beam as described above, the laser beams emitted from each laser light source are usually made into parallel beams by a collimator lens, and then these laser beams are combined into a single laser beam. Generally, the optical paths of the parallel beams are made to be close to each other so that they are incident on the same focusing lens, and the focusing lens focuses the parallel beams on the same focusing position.

(Problem to be Solved by the Invention) However, as described above, each laser beam is not combined into a single beam until it is finally focused by a focusing lens, and the light sources take optical paths close to each other. In this case, each laser beam is incident on different reflection mirrors arranged on the optical path as necessary, or on different positions on the incident surface of the same optical deflector, so the precision of the incident surface may This has the disadvantage that the reflection conditions etc. vary, and the focusing position of each laser beam shifts, making it impossible to perform accurate multiplexing.

The present invention was made in view of the above problems, and by combining multiple laser beams into a single laser beam before the final combining position, each laser beam can be Always keep the conditions constant when entering the optical element,
It is an object of the present invention to provide a multi-laser light source device that enables highly accurate multiplexing.

(Means for Solving the Problems) Laser light sources such as the semiconductor laser described above may have wavelengths that differ by about ±10 to 15 nO1 due to variations during manufacturing. As a result of intensive research in view of this point, the present applicant has discovered that highly accurate multiplexing can be performed by actively utilizing the wavelength difference.

The multi-laser light source device of the present invention based on such knowledge includes:
A plurality of laser beams emitted from a plurality of laser light sources having different wavelengths are incident on a prism from different directions and emitted onto the same optical path, thereby combining the plurality of laser beams. It is something.

(Function) According to this light source device, multiple laser beams can be combined into a single laser beam using a prism by utilizing the wavelength difference of the laser beams, so the prism can be placed at a desired position. If the above-mentioned multiplexing is performed in advance, each laser beam can be combined into a single combined light beam, which can then be appropriately incident on an optical element such as a light deflector or a reflecting mirror. Therefore, the conditions for reflection by the optical element are the same for all laser beams, and the combined light can be correctly focused at a predetermined position regardless of the surface precision of the reflecting surface.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

The figure is a schematic diagram of a multi-laser light source device according to an embodiment of the present invention.

The illustrated multi-laser light source device is used as an example of an optical scanning device, and includes three semiconductor lasers 1, 1', and 1' as laser light sources. These semiconductor lasers1. Laser beams 2, 2' and 2' emitted from 1' and 1' respectively have wavelengths of 10r.
The wavelengths are different by about v, and the wavelengths become longer in the order of laser beam 2, laser beam 2', and laser beam 2'. Three laser light sources 1.1', 1' are arranged with their respective laser emission axes facing inward, and each laser beam 2.2
'.

2' are collimator lenses arranged on the optical path, ;(
3, 3', 3' and becomes a parallel beam, it is focused at positions A, A' by focusing lenses 4.4', 4'.

It is focused at A'. The laser beam 2' becomes a spread beam again from the position A' and enters the entrance lens 6, but the laser beam 2 and the laser beam 2' are reflected by the reflecting mirrors 5A and 5B at the positions A and A', respectively, and are reflected as described above. The light is made incident on the incident lens 6. Note that the above positions A, A', and A' are all on the focal plane of the input lens 6.

Each of the above laser beams 2. 2' and 2' pass through the entrance lens 6 and become parallel beams, which enter the prism 7 from slightly different directions. The prism 7 is selected in advance to have wavelength dispersion suitable for emitting the three laser beams having different wavelengths as described above, which are incident from different directions, onto the same optical path. Laser beam 2.2' synthesized after passing through prism 7
, 2' enter the galvanometer mirror 8 arranged on the optical path.

The galvanometer mirror 8 reciprocates in the direction B in the figure and deflects the combined laser beams 2.2', 2'. Deflected laser beam 2.2'.

2' is focused at a focusing position P by the scanning lens 9. Therefore, if the surface to be scanned is arranged along the locus of this focusing position, the line scanning surface will be
The laser beams emitted by ' are combined and scanned by a high-energy scanning beam. Note that the surface to be scanned is usually a flat surface, and therefore an fθ lens is used as the scanning lens 9.

In the device of this embodiment, the plurality of laser beams to be combined as described above are combined by a prism and then made incident on the galvanometer mirror 8, so that each laser beam 2.2' and 2' The reflection conditions by the galvanometer mirror are constant, and there is no problem that the reflection conditions differ for each beam depending on the surface precision of the reflection surface of the galvanometer mirror 8. Therefore, all of the combined laser beams are correctly focused on a predetermined focusing position P by the scanning lens, achieving highly accurate combining. In addition, even if any optical element such as a reflective mirror is installed on the optical path of the laser beam combined by the prism, not only the galvanometer mirror mentioned above, it will act on the entire laser beam under constant conditions, reducing the accuracy of combining. I won't let you.

It goes without saying that the specific structure of the optical system of the light source device of the present invention is not limited to that shown in the above embodiments, and the laser light source may also be other than a semiconductor laser.

(Effects of the Invention) As explained above, according to the multi-laser light source device of the present invention, the wavelengths of a plurality of laser beams are made to differ by one, and these laser beams are multiplexed by a prism having wavelength dispersion. By doing so, the laser beam can be made into one beam at a desired position. Therefore, even if this combined laser beam is incident on an optical deflector or reflection mirror, its reflection conditions will remain constant, and the combined light will be focused correctly at a predetermined position regardless of the surface accuracy of these optical elements. be able to.

[Brief explanation of the drawing]

The figure is a schematic diagram of a multi-laser light source device according to an embodiment of the present invention. 1, 1', 1'... semiconductor laser 2.2',
2'... Laser beam 7... Prism 8... Galvanometer mirror

Claims (1)

[Claims] A multi-laser light source device that multiplexes a plurality of laser beams by making a plurality of laser beams emitted from a plurality of laser light sources and having different wavelengths enter a prism from different directions and emit them onto the same optical path.