JPH0833524B2 - Semiconductor laser light source device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a semiconductor laser light source device used in a light beam scanning device and the like, and more particularly, to combine laser beams emitted from a plurality of semiconductor lasers into one. The present invention relates to a semiconductor laser light source device.

(Prior Art) Conventionally, a light beam scanning device that deflects and scans a light beam with an optical deflector has been widely put to practical use in various scanning recording devices, scanning reading devices, and the like. A semiconductor laser has been conventionally used as one of means for generating a light beam in such a light beam scanning device.
This semiconductor laser has a number of advantages such as smaller size, lower cost, lower power consumption, and so-called analog direct modulation in which the output is changed by changing the drive current, as compared with a gas laser. In particular, if the semiconductor laser is used as recording light generating means in the scanning recording apparatus, a signal emitted according to image information causes
Since the above direct modulation may be performed, an acousto-optic modulator (AOM) or the like normally used for modulation is not required, which is extremely convenient.

However, while the semiconductor laser has the advantages as described above, in the case of continuous oscillation, at present, the output is small at most 20 to 30 mw, and therefore, a light beam scanning device that requires high energy scanning light, for example, low sensitivity. It is extremely difficult to use it in a scanning recording device for recording on a recording material (DRAW material such as metal film or amorphous film).

In addition, a certain type of phosphor is exposed to radiation (X-ray, α-ray, β-ray,
γ-rays, electron beams, ultraviolet rays, etc.) cause a part of this radiation energy to be accumulated in the phosphor, and when this phosphor is irradiated with excitation light such as visible light, the phosphor changes in accordance with the accumulated energy. Is known to exhibit stimulated luminescence, and using such a stimulable phosphor, the radiation image information of a subject such as a human body is once formed into a layer made of a stimulable phosphor (stimulable phosphor). The stimulable phosphor sheet is recorded, and the stimulable phosphor sheet is scanned with excitation light such as laser light to generate stimulated emission light, and the resulting stimulated emission light is photoelectrically read to generate an image signal. The present applicant has already proposed a radiation image information recording / reproducing system which outputs a radiation image of a subject as a visible image on a recording material such as a photographic light-sensitive material or a CRT based on this image signal (Japanese Patent Laid-Open No. Sho 61-206). 55-12429, same
55-116340, 55-163472, 56-11395, 56-104
No. 645). In this system, it is considered to use a light beam scanning device using a semiconductor laser to read the image information by scanning the stimulable phosphor sheet on which radiation image information is stored and recorded. In order to stimulate the body to emit light, it is necessary to irradiate the phosphor with excitation light of sufficiently high energy. Therefore, a light beam scanning device using the semiconductor laser is used as an image in this radiation image information recording / reproducing system. It is also extremely difficult to use for reading information.

Therefore, in order to obtain a scanning beam of sufficiently high energy from a semiconductor laser having a low optical output as described above, it is considered to use a plurality of semiconductor lasers and combine the laser beams emitted from these semiconductor lasers into one laser beam. (JP-A-60-220308, JP-A-60-264158, etc.).

As a method of combining laser beams in this way,
1) Laser beams are arranged in parallel and are incident on a condenser lens or the like, and are combined at a condensing position. 2) Laser beams whose polarization directions are orthogonal to each other are made incident on polarizing elements from different directions to be on the same optical path. Combined by ejecting,
3) Lights having different wavelengths are made incident on the interference filter from different directions and are emitted on the same optical path to be combined. 4) By utilizing the diffraction phenomenon of light, a diffraction grating or the like is used. There is a method such as multiplexing, but the method 2) is most preferable in order to improve the utilization efficiency of the laser beam and perform the multiplexing with high accuracy.

By the way, the radiation angle of the laser beam emitted from the semiconductor laser is as follows when the direction perpendicular to the pn junction surface of the semiconductor laser is
Since it is 3 to 5 times larger than the direction parallel to the pn junction surface, the cross-sectional shape of the laser beam emitted from the semiconductor laser and passed through the collimator lens arranged facing the semiconductor laser to become a parallel beam is , And has an elliptical shape whose longitudinal direction is perpendicular to the pn junction surface. On the other hand, the polarization direction of the laser beam emitted from the semiconductor laser is the minor axis direction of the ellipse. Therefore, when two laser beams whose polarization directions are orthogonal to each other are made incident on a polarizing element to perform multiplexing as in the above method, the cross section of the combined laser beam has a shape in which an ellipse intersects the cross shape. I will end up. Such light having a cross-shaped cross section is a superposition of mutually incoherent laser beams whose major axis directions (may be referred to as minor axis directions) are orthogonal to each other. Therefore, the diameter of the combined laser beam section is unique. However, the design of the scanning optical system becomes complicated, and the desired scanning optical system does not exist in some cases, which is not preferable in practice.
Therefore, a half-wave plate is placed on one of the optical paths of the laser beams combined by the polarizing element, and the polarization direction is rotated by 90 ° without changing the cross-sectional shape. There is also proposed a semiconductor laser light source device in which the longitudinal directions of the beam cross sections of the laser beam are made to coincide with each other (Japanese Patent Publication Sho-60-5).
No. 3857).

(Problems to be Solved by the Invention) By the way, in order to accurately match the cross sections of two laser beams after combining in the apparatus for combining using the polarizing element and the half-wave plate as described above. It is necessary to improve the mounting position accuracy of both semiconductor lasers and align the major axis (minor axis) of the cross sections of both laser beams when emitted from the semiconductor lasers in advance. However, since the semiconductor laser is usually fixed to the laser mount, it is difficult to always precisely position the semiconductor laser in the rotation direction around the laser emission axis when mounting the semiconductor laser. Further, once the semiconductor laser is fixed to the laser mount, it is very difficult to change the position thereafter. Further, when the position adjustment of the semiconductor laser in the rotation direction is intentionally performed on the laser mount, the semiconductor laser cannot be changed. Is liable to be misaligned not only in its rotation direction but also in a straight line direction such as vertical and horizontal directions on the semiconductor laser supporting surface of the mount, so that the long axis directions of the two laser beams should be strictly overlapped when they are combined. It is difficult to adjust to. In this way, when the long-axis directions of the two laser beams do not sufficiently match at the time of combining, the focused spot diameter when the combined laser beams are focused by a focusing lens or the like is larger than the predetermined focused spot diameter. When the radiation image information is read from the above-mentioned stimulable phosphor sheet using such a laser beam, the quality of the reproduced image finally obtained will deteriorate.

The present invention has been made in view of the above problems,
In a device for combining two laser beams by using a polarization element, the major axis directions of the beam cross sections of the two laser beams are relatively adjusted and the two laser beams are superposed on each other on the optical path after combining with high precision. It is an object of the present invention to provide a semiconductor laser light source device that can be manufactured.

(Means for Solving the Problem) A first semiconductor laser light source device according to the present invention includes a first laser beam and a second laser beam which are combined by being incident on the above-described polarizing element from different directions. The first semiconductor laser and the second semiconductor laser that emit light are arranged so that the polarization directions of the first laser beam and the second laser beam are substantially orthogonal to each other when entering the polarizing element. Of the laser beam and the second laser beam, on the optical path before the incidence of the polarizing element, a beam cross-section shape rotating means for rotating the cross-section shape of the laser beam is arranged, and the beam cross-section shape rotating means It is characterized in that the longitudinal directions of the cross sections of the first laser beam and the second laser beam are relatively rotated by about 90 °.

Here, the fact that the longitudinal direction is relatively rotated by about 90 ° means that the relative rotation angle in the longitudinal direction when the both laser beams are guided to the optical paths parallel to each other is about 90 °. , So the beam cross section is thus relatively 90 °
The two laser beams that have been rotated are such that the longitudinal directions of the beam cross sections thereof coincide with each other in the optical path after combining.

The second semiconductor laser light source device according to the present invention includes a first laser beam and a second laser beam that are combined by a polarizing element.
A beam cross-section shape rotating means for rotating the cross-sectional shape of the laser beam is arranged on the optical path of at least one of the laser beams before entering the polarizing element, and the beam cross-section shape rotating means is arranged on the optical path. A half-wave plate is disposed on the optical path of the first laser beam and / or the second laser beam before entering the polarizing element, and the half wavelength plate of the first laser beam and the second laser beam The polarization directions are made substantially orthogonal to each other when entering the polarizing element, and the longitudinal directions of the cross sections of the first laser beam and the second laser beam are made to coincide on the optical path after passing through the polarizing element. It is characterized by.

In any device, the beam cross-section shape rotating means means that the beam shape can be rotated around the emission axis of the laser beam, and the rotation angle can be arbitrarily determined by selecting the rotating means having appropriate characteristics. As long as it can be used, specifically, a Dove prism or the like is preferably used. Further, the above-mentioned polarizing element means an element capable of separating and combining light according to the polarization direction, and specifically,
There is a uniaxial crystal such as a Wollaston prism or a polarization beam splitter in which a dielectric multilayer film is deposited on the prism.

(Operation) In each of the above two semiconductor laser light source devices, since the cross section of at least one laser beam is rotated by using the beam cross section shape rotating means, the longitudinal direction of the cross sections of the two laser beams is changed. They can be matched on the optical path after multiplexing. Along with this, in the device of the present invention, even if the first and / or the second semiconductor laser is slightly rotated from the predetermined mounting position on the laser mount, the position of the beam sectional shape rotating means is finely adjusted. Thereby, the longitudinal directions of the cross sections of the two laser beams on the optical path after the multiplexing can always be accurately matched.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

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

A first laser beam 2 emitted from the first semiconductor laser 1 passes through a collimator lens 3 to become a parallel beam, and then passes through a Dove prism 4 which is a beam cross-section shape rotating means, and a polarized light which is a polarization element. It is incident on the beam splitter 5. On the other hand, the second laser beam 12 emitted from the second semiconductor laser 11 passes through the collimator lens 13 to become a parallel beam, and then the polarization beam splitter 5 is moved in a direction perpendicular to the first laser beam 2. Incident on.

The polarizing film 5a of the polarizing beam splitter 5 transmits p-polarized light and reflects s-polarized light as an example. Further, the first semiconductor laser 1 and the second semiconductor laser 11 are arranged such that the pn junction surfaces (not shown) of the internal semiconductor elements are orthogonal to each other. The polarization direction of the laser beam 2 of 1 is the plane of polarization
5a is p-polarized, and the second semiconductor laser 11 has a second laser beam 12 whose polarization direction is s with respect to the polarization plane 5a.
It is attached to a laser mount (not shown) so that it becomes polarized light. Therefore, the first laser beam 2 passes through the polarization beam splitter 5 and the second laser beam 2
Reference numeral 12 reflects the polarization beam splitter 5, and both laser beams are emitted on the same optical path and combined.

By the way, the sectional shapes of the first and second laser beams 2 and 12 emitted from the first and second semiconductor lasers 1 and 11 are elliptical, but the longitudinal direction is the polarization direction of each laser beam. Therefore, if the two laser beams 1 and 12 are combined as they are, the cross section of the combined laser beams will have an elliptical cross shape. Therefore, in this device, as described above, the Dove prism 4 is arranged on the optical path of the first laser beam 2, and its cross-sectional shape is changed before the first laser beam enters the polarization beam splitter 5. It is designed to rotate 90 °. When the first laser beam 2 is incident on the Dove prism 4 in this manner, the longitudinal direction of the cross section of the laser beam after passing through the Dove prism becomes the same as the polarization direction. Therefore, when the first laser beam 2 and the second laser beam are combined by the polarization beam splitter 5, the obtained laser beam becomes uniform in the longitudinal direction. When the laser beams combined as described above are focused by a focusing optical system including an anamorphic optical system, the focusing spot L becomes a circle as shown in FIG. The integrated beam intensities are approximately equal to the Couse distribution as shown in FIG. When the Dove prism 4 is arranged on the optical path of the first laser beam to rotate the beam cross section as in this embodiment, the first and / or second semiconductor lasers 1, Even when 11 is slightly rotated from the predetermined mounting position, the position of the Dove prism 4 is finely adjusted to change the longitudinal direction of the cross section of the first laser beam 2 to the cross section of the second laser beam 12. Since they can be aligned with the longitudinal direction, the major axis directions of both laser beams can be aligned with high accuracy without adjusting the position of the semiconductor laser.

The dove prism 4 may be arranged on the optical path of the second laser beam, or may be arranged on the optical paths of the first and second laser beams, respectively. When the dove prism is installed on the optical path of both laser beams, the two dove prisms make the longitudinal direction of both beam cross sections relatively 90 °.
Each Dove prism may be selected and used so that it can be rotated.

Further, the polarization direction of the laser beam that has passed through the Dove prism may be slightly rotated, and when the polarization direction of the laser beam is rotated from a predetermined direction, the amount of light guided by the polarization beam splitter to the optical path after combining is reduced. . Therefore, when the laser beam passes through the Dove prism, the ratio of the amount of light that is reflected or transmitted by the polarization beam splitter and guided to the predetermined combining optical path in the laser beam entering the polarization beam splitter becomes lower than about 70%. In this case, as shown in FIG. 3, the half-wave plate 6 is provided on the optical path of the laser beam (the first laser beam 2 in FIG. 3) in which the Dove prism is arranged on the optical path.
Is preferably provided to correct the polarization direction. In this way, by using the 1/2 wavelength plate 6 to rotate the polarization direction slightly rotated by passing through the Dove prism 4 in the opposite direction to correct the polarization direction, it is possible to prevent a decrease in the light amount after the laser beams are combined. You can The half-wave plate 6 may be provided between the first semiconductor laser 1 and the dove prism 4 instead of being provided between the dove prism 4 and the polarization beam splitter 5 as shown in FIG. In the case where the Dove prism and the half-wave plate are used together as in the above embodiment, the position in the rotation direction of the semiconductor laser in which these optical elements are arranged on the optical path of the laser beam is set. It can be set arbitrarily. That is, such a semiconductor laser can be arbitrarily adjusted with respect to the polarization direction by rotating the half-wave plate, and the position in the rotation direction of the beam cross section can be arbitrarily adjusted by selecting the Dove prism. If the rotational position is adjusted so that only the other semiconductor laser passes through the polarization beam splitter satisfactorily, multiplexing can be performed well. In addition, the Dove prism and 1 / on the optical path of both laser beams
When two wavelength plates are arranged together, the position in the rotation direction of any semiconductor laser can be set arbitrarily.

In any of the above-described embodiments, the beam cross-section shape rotating means for rotating the beam cross-section is capable of rotating the beam cross-section shape by a desired angle while substantially maintaining the polarization direction of the laser beam. Any member can be used without being limited to the above-mentioned Dove prism.

Next, as a usage example of the semiconductor laser light source device of the present invention,
A radiation image information reading apparatus using the apparatus as excitation light generating means will be described with reference to FIG.

The illustrated device is a laser beam 22 that is emitted from the above-mentioned semiconductor laser light source device 10 and has a high output due to multiplexing.
The scanning is performed to read the stimulable phosphor sheet 31 in which the radiation image information is accumulated and recorded. After passing through the cylindrical lens 29, the laser beam 22 is incident on the rotary polygon mirror 23 rotating in the direction of arrow A as a line image perpendicular to the rotation axis of the rotary polygon mirror. The laser beam 22 reflected and polarized by the rotating polygon mirror 23 rotating in the direction of arrow A passes through the fθ lens 24, the cylindrical lens 25, and the cylindrical mirror 26 arranged on the optical path, whereby the stimulable phosphor sheet 31 is formed. Focused on above,
The endless belt device 32 repeatedly carries out main scanning in the arrow X direction as excitation light on the stimulable phosphor sheet 31 conveyed (sub-scanned) in the arrow Y direction. As described above, from the location of the stimulable phosphor sheet 31 which is two-dimensionally scanned by the laser beam 22, stimulated emission light according to the image information stored and recorded therein is generated, and this stimulated emission light is The incident end face is arranged along the main scanning line and is incident on the light guide 27 in which the photo end face is connected to the photo multiplier 28 as a photoelectric reading means, and is transmitted by total reflection in the inside of the light guide 27 so that the photo multiplier Detected by 28. The photomultiplier 28 converts the stimulated emission light into an electric signal, and the electric signal thus obtained is subjected to necessary image processing and then sent to a CRT or an image scanning recording device for image reproduction. As described above, when the semiconductor laser light source device of the present invention is used as the excitation light generating means, the stimulable phosphor sheet is irradiated with the laser beam having a high output due to the combination, so that the excitation of the laser beam is sufficient. A sufficient amount of stimulated emission light is generated, and good image information can be read.

The semiconductor laser light source device of the present invention is well used for reading a stimulable phosphor sheet as described above, and detects information transmitted from a film by irradiating the film with information recorded on the film. Therefore, it is also suitably used in a reading device for reading and an optical scanning recording device for recording various information on a recording material having a relatively low sensitivity.

(Effect of the Invention) As described above, according to the semiconductor laser light source device of the present invention, by providing the beam cross-section shape rotation means on the optical path of the laser beam, the two laser beams are aligned in the major axis direction. The beam cross section can be matched on the optical path after the wave, and even if the laser beam cross section is rotated by a small amount due to a mounting error of the semiconductor laser, the rotation can be easily corrected by the beam cross section shape rotation means, so that high accuracy is always obtained. It is possible to realize multiplexing of laser beams.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a semiconductor laser light source device according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing a sectional state of a laser beam combined in the above device, and FIG. FIG. 4 is a schematic perspective view of a semiconductor laser light source device according to this embodiment, and FIG. 4 is a perspective view of a radiation image information reading device using the light source device of the present invention. 1 ... First semiconductor laser 2 ... First laser beam 3,13 Collimator lens 4 Dove prism 5 Polarizing beam splitter 6 1/2 wave plate 10 Semiconductor laser light source device 11 …… Second semiconductor laser 12 …… Second laser beam

Claims (2)

[Claims] 1. A first laser beam emitted from a first semiconductor laser and a second laser beam emitted from a second semiconductor laser.
In the semiconductor laser light source device which makes the laser beams of different directions incident on the polarizing element from different directions, emits the same in the optical path after passing through the polarizing element, and combines the two, the first semiconductor laser and the second semiconductor laser are:
At least one of the first laser beam and the second laser beam is arranged so that the polarization directions of the first laser beam and the second laser beam when entering the polarizing element are substantially orthogonal to each other. On the optical path before the incidence of the polarizing element, a beam cross-section shape rotating means for rotating the cross-sectional shape of the laser beam is provided, and the beam cross-section shape rotating means causes the first laser beam and the second laser beam to rotate. A semiconductor laser light source device characterized in that the longitudinal direction of its cross section is relatively rotated by about 90 °. 2. A first laser beam emitted from a first semiconductor laser and a second laser beam emitted from a second semiconductor laser.
Of the first laser beam and the second laser beam, in which a laser beam of 1) is made incident on a polarizing element from different directions, is emitted to the same optical path after passing through the polarizing element, and is multiplexed. One of the beam cross-section shape rotating means for rotating the cross-sectional shape of the laser beam is arranged on the optical path before entering the one polarizing element, and the beam cross-section shape rotating means is arranged on the optical path. Laser beam and /
Alternatively, a half-wave plate is arranged on the optical path of the second laser beam before entering the polarizing element, and the polarization directions of the first laser beam and the second laser beam are incident on the polarizing element. In this case, the semiconductor laser light source device is made to be substantially orthogonal to each other, and the longitudinal directions of the cross sections of the first laser beam and the second laser beam are made to coincide on the optical path after passing through the polarizing element. .