JP2631666B2 - Laser light source device for multiplexing - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplexing laser light source device that can combine a low-power laser beam emitted from a semiconductor laser light source to obtain a high-power laser beam. More particularly, the present invention relates to a multiplexing laser light source device that can easily adjust the position of a laser beam for multiplexing.

(Prior Art) As is well known, an optical scanning device that deflects and scans a laser beam by an optical deflector is widely used in, for example, various scanning recording devices and scanning reading devices. In a scanning apparatus, for example, in order to speed up reading and recording, it has been studied 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 or the like. That is, semiconductor lasers have many advantages such as small size, low cost and low power consumption compared to gas lasers and the like, and direct modulation is possible by changing the drive current. At present, the output is as low as 20 to 30 mw at most, and therefore, a light beam scanning device that requires high-energy scanning light, for example, a scanning recording device that records on a recording material with low sensitivity (such as a DRAW material such as a metal film or an amorphous film). It is very difficult to use it for such purposes.

In addition, radiation (X-ray, α-ray, β-ray,
(γ-rays, electron beams, 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 irradiated according to the accumulated energy. Is known to exhibit stimulated emission, and by utilizing such a stimulable phosphor, radiation image information of a subject such as a human body is temporarily stored in a stimulable phosphor sheet having a layer composed of a stimulable phosphor. Record and scan this stimulable phosphor sheet with excitation light such as laser light to produce photostimulated light,
An image signal is obtained by photoelectrically reading the obtained stimulated emission light, and a radiation image of the subject is output as a visible image to a recording material such as a photographic photosensitive material or a CRT based on the image signal as a visible image. A system has already been proposed by the present applicant (Japanese Patent Laid-Open Nos. 55-12429 and 55-116340).
Nos. 55-163472, 56-11395, 56-104645). In this system, an optical scanning device using a semiconductor laser is considered to scan the stimulable phosphor sheet on which the radiation image information is accumulated and recorded to read the image information. In order to read a sheet at high speed, it is necessary to irradiate the phosphor with excitation light of sufficiently high energy. Therefore, an optical scanning device using the semiconductor laser is required to read image information in this radiation image information recording / reproducing system. Very difficult to use for.

Therefore, as described above, in order to obtain a scanning beam of sufficiently high energy from a semiconductor laser having a low light output, it is desirable to use a plurality of laser light sources and combine the laser beams emitted from these laser light sources into one. (in this case,
Each laser beam may be multiplexed into one on the optical path to the scanning point, or may be multiplexed into one on the scanning point.)

In order to combine laser beams emitted from a plurality of laser light sources into one laser beam as described above, the laser beams emitted from the respective laser light sources are usually collimated by a collimator lens and then focused. The lenses are focused at the same focusing position. Therefore, in order to combine laser beams with high accuracy, it is necessary to precisely control the position of each laser beam so that the laser beam is properly focused at a predetermined focusing position. When focusing on one laser beam used for multiplexing, the optical system is composed of one laser light source, a collimator lens, and a focusing lens, and the position control of the laser beam is usually performed by the laser light source and the collimator. This is performed by finely adjusting the position relative to the lens.

(Problems to be Solved by the Invention) However, when the focusing position is adjusted by relatively moving the laser light source and the collimator lens as described above for each of the combined laser beams, Since the collimator lens and the collimator lens must be relatively moved at a very small level, there is a disadvantage that position adjustment is difficult. The problem of such position adjustment will be described with reference to FIG.

In the illustrated multiplexing laser light source device, a laser beam 102 emitted from a semiconductor laser 101 as a laser light source is used.
Is converted into a parallel beam by the collimator lens 103,
The light passes through the focusing lens 105 and is focused at the position P. The laser beam 102 is multiplexed with another laser beam at a predetermined convergence position, but when the convergence position P is shifted from the predetermined convergence position P ′ by ΔX, the collimator lens 103 is moved by a broken line in the drawing. Δx at the position indicated by
Just need to move. Relationship [Delta] X and [Delta] x is expressed a focal length of the collimator lens 103 f _103, when the collecting point distance of the focusing lens 105 to _{f 105 ΔX = (f 105 /} f 103) · Δx. For example, in reading radiation image information in the above-described radiation image information reading and reproducing system, the scanning position accuracy of the laser beam is required to be about ± 10 μm, so that the light source device is used in an optical scanning device that reads radiation image information. It is necessary to adjust the focusing position of the laser beam at a level that satisfies the above-described scanning position accuracy.
Therefore, as an example, ΔX is 10 μm, f ₁₀₃ is 6 mm, f
Assuming that ₁₀₅ is 360 mm, Δx is (f ₁₀₃ / f ₁₀₅ ) ΔX
Is given by Δx = 1/6 μm.
It is very difficult to adjust the position of the collimator lens of the light source device at a minute level of μm or less.

The present invention has been made in view of the above problems,
It is an object of the present invention to provide a multiplexing laser light source device capable of relatively easily adjusting the position of a laser beam with high accuracy.

(Means for Solving the Problems) A multiplexing laser light source device of the present invention is provided on an optical path of a semiconductor laser light source and a laser beam emitted from the semiconductor laser light source, and converts the laser beam into a parallel beam. A collimator optical system, and a focusing optical element such as a focusing lens for focusing the parallel beam at a predetermined position,
The collimator optical system includes a first lens member disposed on the semiconductor laser light source side and a second lens member disposed on the focusing optical element side, and has a focal length of the second lens member. An absolute value is larger than an absolute value of a focal length of the first lens member, and the second lens member moves in a direction along an optical axis of the second lens member independently of the first lens member. And the position can be adjusted in a plane perpendicular to the optical axis.

The first lens member and the second lens member may be members having a focal length in the above relationship and acting as a predetermined lens. In addition to a normal light transmission type lens, a concave mirror may be used. , A convex mirror, or the like. Further, the focusing optical element may be a concave mirror other than the focusing lens described above.

(Operation) In the above device, a collimator optical system including two lens members is provided instead of the conventional collimator lens,
By making the second lens member having a large focal length of this optical system movable, when the laser beam is displaced at the focus position, the second lens member is moved relatively largely to provide a highly accurate laser beam. The beam position can be adjusted. That is, assuming that the focal length of the focusing optical element is f and the focal length of the second lens member is f ′, the amount Δx of moving the second lens member when the laser beam is to be moved by ΔX at the focusing position is Δx
= (F '/ f) ΔX, and as f ′ increases, Δx
Also increases. Therefore, it is possible to finely adjust the convergence position of the laser beam by moving the second lens member more than the conventional collimator lens by increasing f ′ by combining or disposing the first lens member. Become.

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

FIG. 1 is a side view of a multiplexing laser light source device according to an embodiment of the present invention.

In the illustrated light source device, a laser beam 2 emitted from a semiconductor laser 1 as a laser light source
And a collimator optical system 10 composed of a second lens 4 to form a parallel beam.
Is focused on a predetermined position. In this embodiment, the first lens 3 has a focal length f ₃ of 6 mm, the second lens 4 has a focal length f ₄ of 180 mm, and the focal length f of the focusing lens 5.
₅ is 360mm. The collimator optical system 10, the laser emitted from the first lens 3 and the first lens 3 set slightly smaller than the focal length f ₃ of the distance l first lens 3 and the laser emitting surface of the semiconductor laser 1 By arranging a beam having a long focal length suitable for converting the divergent beam into a parallel beam as the second lens 4, the incident laser beam is converted into a parallel beam. It is assumed that.

The second lens 4 can be moved by a position adjusting means (not shown) in a three-dimensional direction of x and y directions orthogonal to each other in a plane perpendicular to the optical axis of the lens 4 and a Z direction parallel to the optical axis of the lens. It has become. The semiconductor laser 1, the first lens 3, and the focusing lens 5 are fixed at predetermined positions. The semiconductor laser 1 laser emitted from the beam 2 of the first lens 3, the second lens 4, and passes through the focusing lens 5 upon focusing at a position P _1, the focusing position is predetermined convergence position P If that was shifted by [Delta] x ₁ is from ₂ x direction, the second lens 4 is moved to the position indicated by the broken line in the drawing laser beam 2 focused position is correctly positioned P ₂
Adjust so that Set the focusing position of laser beam 2 to P ₁
Movement amount [Delta] x ₁ of the second lens 4 required to move to the P ₂ by the [Delta] X ₁ from Because represented by _{Δx 1 = (f 4 / f} 5) · ΔX 1, ΔX 1 is 10μm as an example (18
0/360) · 10 μm = 5 μm On the other hand, unlike the conventional apparatus, the laser beam 2 is made parallel by only the first lens 3 having a short focal length without providing the second lens 4, and the first lens 3 is also corrected for the focusing position. In the case of moving the focal point, the amount of movement of the lens 3 required to move the focusing position by 10 μm is (6/360) · 10 μm = 1/6 μm.
Therefore, in the present apparatus, the amount of movement of the lens for moving the focal position in the x direction is about 30 times that of the conventional apparatus, and the adjustment of the lens position becomes easy. The relationship between the amount of movement of the focusing position and the amount of movement of the second lens is the same in the y direction.

Also, as shown in FIG.
If the P ₃ is deviated by [Delta] Z ₁ in the Z direction from the predetermined convergence position P _4, the focusing position of the laser beam 2 is moved by Delta] z ₁ in the position shown the second lens 4 in broken line in the figure Is moved to a predetermined position. The movement amount Δz ₁ of the second lens
And ΔZ ₁ above is Therefore, assuming that ΔZ ₁ is 1 mm, Δz ₁ becomes (1
^80/360) a ² · 1mm = 0.25mm. When performing the above correction by moving the first lens 3 in the Z direction, Because Therefore, adjustment becomes difficult. On the other hand, when the above correction is performed, the movement amount of the second lens 4 is 900
Therefore, the use of the present apparatus makes it possible to adjust the focusing position in the Z direction, which was conventionally difficult in practice.

As described above, according to the above-described embodiment, the laser beam is made parallel by the collimator optical system composed of two lens members instead of the conventional collimator lens, and the focal length of the two lens members located on the converging lens side. By moving the long lens member, the lens member having a long focal length can be relatively moved when adjusting the focusing position of the laser beam. Therefore, it is easier to adjust the focal position than before, and highly accurate laser beam multiplexing is realized.

In the above embodiment, the first lens member and the second lens member
Although the example in which each of the lens members is formed of a single lens has been described, both lens members may be formed by combining a plurality of lenses. Further, the second lens member is not limited to the light transmission type lens as described above, and may be a concave mirror having a similar focal length. Further, if the first lens member is disposed slightly away from the semiconductor laser than its own focal length, and the laser beam passing through the first lens member is made to be a beam that is focused slightly inward from the parallel beam, the second lens member can be obtained. A concave lens (convex mirror) can be used as the lens member.

The multiplexing semiconductor laser light source device described above is, for example,
As shown in the figure, it is used as an optical scanning device or the like in combination with another semiconductor laser light source device.

The illustrated optical scanning device is, for example, a combination of three semiconductor laser light source devices. The three semiconductor lasers 1, 1 ', 1 "of each light source device are arranged with their beam emission axes aligned in parallel with each other. For each of the semiconductor lasers 1, 1 ', 1 ", a first lens 3, 3', 3" and a second lens 4,
Collimator optical systems 10, 10 ', 10 "comprising 4', 4" and reflection mirrors 6, 6 ', 6 "are disposed. Laser beams 2, 4 emitted from respective semiconductor lasers 1, 1', 1" are arranged. 2 ', 2 "are made into parallel beams by the collimator optical system 10, 10', 10", and these parallel beams 2, 2 ', 2 "are reflected by the reflection mirror.
After being reflected by 6, 6 ', 6 "and passing through a beam splitter 7, which will be described later, the light enters a common galvanometer mirror 8.

The galvanometer mirror 8 reciprocates in the direction A in the figure,
The parallel beams 2, 2 ', 2 "are deflected. The deflected parallel beams 2, 2', 2" are concentrated by the common focusing lens 5 at one focusing position P and are focused at this focusing position. You. Therefore, if the scanning surface is arranged along the trajectory of the focusing position, the scanning surface will be the semiconductor lasers 1, 1 ',
The laser beam emitted from the 1 "is multiplexed and scanned by a scanning beam having high energy. Usually, the surface to be scanned is a flat surface.
Is an fθ lens.

Correction of the displacement of each of the laser beams 2, 2 ', 2 "
The detection may be performed by detecting whether or not each laser beam is correctly focused on the focusing position P. However, in the illustrated device, a part of the laser beam incident before the galvanometer mirror 8 is reflected, The remaining beam splitter 7 to be transmitted is arranged, and the laser beam reflected by the beam splitter 7 is focused by the monitoring focusing lens 15 to detect whether or not the focusing position P ″ of each laser beam is a predetermined position. In other words, the semiconductor lasers 1, 1 ', 1 "are driven one by one before starting the optical scanning, and the laser beams 2, 2 emitted from the respective semiconductor lasers are started. The positions of the second lenses 4, 4 ', 4 "are adjusted so that the light reflected by the beam splitters 7', 2" is focused to the correct focusing position. If the laser beam is branched and the focus position on the surface to be scanned is monitored, and the second lens is adjusted based on the monitored focus position, the position sensor is always disposed at the detection position. This is convenient because adjustments can be made whenever necessary.

The laser light source in the laser light source device of the present invention is not limited to the above-described semiconductor laser, but may be a light emitting diode or any other light source.

(Effect of the Invention) As described above, according to the multiplexing laser light source device of the present invention, a collimator optical system including two lens members is provided in place of the conventional collimator lens, and the position adjustment of the laser beam is performed by the above-described optical system. By moving the second lens member having a long focal length in the system, the amount of movement of the lens member necessary for adjusting the laser beam is increased, and the adjustment is facilitated. Therefore, the present light source device can be used in combination with another light source device even in an optical scanning device or the like that needs to adjust the position of a laser beam with high precision.

[Brief description of the drawings]

1 and 2 are side views of a multiplexing laser light source device according to an embodiment of the present invention, FIG. 3 is a schematic diagram of an optical scanning device using the light source device of the present invention, and FIG. It is a side view of a light source device. DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser, 2 ... Laser beam 3 ... First lens, 4 ... Second lens 5 ... Converging lens, 10 ... Collimator optical system

Claims (1)

(57) [Claims] 1. A semiconductor laser light source, a collimator optical system provided on an optical path of a laser beam emitted from the semiconductor laser light source and configured to make the laser beam a parallel beam, and a focusing device that focuses the parallel beam at a predetermined position A multiplexing laser light source device, comprising: an optical element for multiplexing the laser beam with another laser beam at the predetermined position, wherein the collimator optical system has a first lens disposed on the semiconductor laser light source side. A second lens member disposed on the side of the focusing optical element, wherein the absolute value of the focal length of the second lens member is larger than the absolute value of the focal length of the first lens member, The position of the second lens member can be adjusted independently of the first lens member in a direction along the optical axis of the second lens member and in a plane perpendicular to the optical axis. And a laser light source device for multiplexing.