JPH0436730A - Laser deflector - Google Patents

Abstract

PURPOSE:To reduce the size of the laser deflector by modulating a laser beam from a semiconductor laser and diffracting the laser beam by a diffracting grating. CONSTITUTION:When the oscillation wavelength of laser beams 100 radiated from a laser diode 1 is changed by a modulating circuit 4, primary light 102 diffracted by the diffraction grating 2 is scanned only by DELTAtheta. Namely when the parallel laser beams 100 are made vertically incident upon the grating 2 whose grating interval is (d), its transmitted beams are divided into the 0-th order light 101 to be straight advanced and the primary light 102 advancing in the direction satisfying the relation of sintheta=lambda/d. Thereby, the bending angle thetaof the laser beams 100 can be changed by changing the value of (d) or lambda.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser deflector, and more particularly to a laser deflector that deflects and scans the light of a semiconductor laser in an optical device or the like.

[Prior Art] Conventionally, optical deflectors for scanning light such as laser light are known, which are used in laser beam printers, POS barcode scanners, displays (art), and the like. Conventionally, various devices have been developed as optical deflectors for scanning this light. Fig. 6A is a schematic diagram for explaining the principle of an optical deflector using a conventional galvanometer, and Fig. 6B is a schematic diagram for explaining the principle of an optical deflector using a conventional galvanometer. It is a perspective view showing a container. First, the principle of an optical deflector using a galvanometer will be explained with reference to FIG. 6A. What is a galvanometer?
It refers to a moving coil that rotates within one rotation when a current is applied to it, and a mirror is attached to this moving coil, which is a galvanometer, to scan the laser beam 100. Specifically, when a drive current is applied to the magnetic driver 12, the mirror 11 rotates within one rotation, and the mirror 11 rotates within one rotation.
The laser beam 100 incident on is scanned. The rotation angle of the mirror 11 is detected by a position sensor 13, and the drive current flowing to the magnetic driver 12 is controlled based on the detection result.

An optical deflector using such a galvanometer is specifically constructed of elements as shown in FIG. 6B. That is, a negative lens 14 into which the laser beam 100 is incident, a positive lens 15 into which the light that has passed through the negative lens 14 is incident, and an It is composed of an axial mirror 11a and a Y-axis mirror 11b for controlling scanning of the laser beam 100 in the Y-axis direction. In operation, the negative lens 14 and the positive lens 15
The laser beam 100 that has passed through the X-axis mirror 11a and the Y-axis mirror 11b is scanned onto the object to be scanned 16. Here, the X-axis mirror 11a and the Y-axis mirror 11b are configured to rotate based on a drive current according to the galvanometer principle shown in FIG. It is scanned in the X and Y axis directions.

FIG. 7 is a perspective view showing a conventional optical deflector using a polygon mirror. Referring to FIG. 7, the optical deflector includes a semiconductor laser 21 for generating a laser beam 100, a coupling lens 27 for condensing the laser beam 100, and a laser beam condensed by the coupling lens 27. A polygon mirror 28 for scanning the laser beam 100 by reflecting the laser beam 100 while rotating it; a motor 23 for rotating the polygon mirror 28; It is composed of a correction lens 29 for correcting wobbling. In operation, the laser beam 100 emitted from the semiconductor laser 21 is focused by the coupling lens 27, and the focused laser beam 100 is reflected by the polygon mirror 28 rotated by the motor 23. Here, if the laser beam 100 is incident on the polygon mirror 28 while it is rotating, the reflected light will be scanned in the horizontal direction. The laser beam scanned by the polygon mirror 28 is scanned after its vertical fluctuation is corrected by the correction lens 29.

FIG. 8 is a schematic diagram showing an optical deflector using a conventional acousto-optic element. Referring to FIG. 8, the optical deflector using this acousto-optic element includes a sound absorbing material 31, a TeO2 acousto-optic medium 32, a transducer 33, and a high frequency oscillator 34.
It is composed of.

In operation, a high frequency wave oscillated by a high frequency oscillator 34 is converted into an ultrasonic traveling wave 40 by a transducer 33. When the frequency of the high frequency applied to this transducer 33 is changed by the high frequency oscillator 34, TeO
The laser light 100 that is incident on the second acousto-optic medium 32 and passes through the ultrasonic traveling wave 40 becomes diffracted light corresponding to the zeroth order diffracted light and the high frequencies f, , f2 given by the high frequency oscillator 34. That is, by controlling the frequency of the high-frequency oscillator 34, it is possible to scan the diffracted light of the laser beam 100 passing through the ultrasonic traveling wave 40.

[Problems to be Solved by the Invention] As mentioned above, conventional optical polarizers for scanning laser beams and the like are those using the galvanometer shown in Figures m6A and 6B, and the polygon mirror shown in Figure 7. There are known devices using an acousto-optic device as shown in FIG. 8.

However, the optical deflector using a galvanometer shown in FIGS. m6A and 6B and the optical deflector using a polygon mirror shown in FIG. 7 have the problem that the device becomes large and expensive.

In addition, in the optical deflector using the acousto-optic element shown in FIG. 8, it is necessary to apply a variable high frequency wave using the high frequency oscillator 34, and the drive circuit required for this is large and expensive. There was a problem.

In other words, since the conventional optical deflector is large and expensive, it has been difficult to achieve miniaturization and cost reduction of the device, which is the demand of the market.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide an optical deflector that can reduce the size and cost of the device.

[Means for Solving the Problem] The invention in the first claim includes a semiconductor laser for emitting laser light, a modulation circuit for modulating the semiconductor laser, and a diffraction system for diffracting the laser light emitted from the semiconductor laser. and a diffraction grating for.

The invention according to the second claim is characterized in that the diffraction grating is provided in the emission window of the semiconductor laser.

The invention in claim 3 is characterized in that the diffraction grating controls the plane of polarization of light by controlling the direction in which it is arranged.

[Function] In the laser deflector according to the present invention, the laser beam is emitted by the semiconductor laser, the semiconductor laser is modulated by the modulation circuit, and the laser beam emitted from the semiconductor laser is diffracted by the diffraction grating, so that the structure of the device is Laser light scanning is performed without complicating the process.

[Embodiments of the invention] Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic diagram showing the configuration of an optical deflector according to an embodiment of the present invention. Referring to FIG. 1, the optical deflector includes a laser diode 1 for emitting laser light 100;
A diffraction grating 2 for diffracting the laser beam 100 emitted from the laser diode 1; a light shielding plate 3 for shielding the zero-order light 101 traveling straight among the laser beam 100 passing through the diffraction grating 2; and the laser diode 1. A modulation circuit 4 for changing the oscillation wavelength of the laser diode 1 by controlling the current applied to the laser diode 1 is included. The modulation circuit 4 includes a variable resistor 4a and a power source 4b.

In operation, by changing the oscillation wavelength of the laser beam 100 emitted from the laser diode 1 by the modulation circuit 4, the primary beam 102 diffracted by the diffraction grating 2 is
is scanned by Δθ.

FIG. 2 is a schematic diagram for explaining the deflection principle of the diffraction grating 2 shown in FIG. 1. Referring to FIG. 2, when parallel laser light 100 is perpendicularly incident on the diffraction grating 2 whose spacing is d, the transmitted light is divided into zero-order light 101 traveling straight and sin θ-λ/ It is divided into primary light 102 which travels in the direction of θ which satisfies the relationship of 8. Therefore, d or λ
By changing the bending angle θ of the laser beam 100,
can be changed. FIG. 3 is a graph for explaining the relationship between the wavelength and oscillation intensity of the laser diode shown in FIG. 1. Referring to FIG. 3, it can be seen that the oscillation spectrum (wavelength) of the laser beam 100 has a predetermined width. Therefore, by controlling the current applied to the laser diode 1, its oscillation wavelength can be changed. That is, by changing the value of λ explained in FIG.
00, the primary light 102 can be deflected (scanned). As a specific deflection method, the primary light 102 that has passed through the diffraction grating 2 is transmitted at an angle of sin θ-λ/8.

Here, when the current applied to the laser diode 1 by the modulation circuit 4 is changed, the diffraction angle sin θ of the primary light 102
The angle -λ/d is deflected by sinΔθ−Δλ/d. Note that if d is formed to be on the wavelength order (1 micron), θ: can be changed by modulating Δλ by about 10 nm.
Deflection of about sin θ-10/1000-10-2 (rad) is possible.

FIG. 4 is a perspective view showing a laser diode of an optical deflector according to a second embodiment of the present invention. Referring to Figure 4,
In this embodiment, the protective glass 1 of the laser diode 1
A diffraction grating 2a is formed in a. With this configuration, the device can be further miniaturized. In this embodiment, the diffraction grating 2a is formed on the protective glass la of the laser diode 1 itself, but the present invention is not limited to this. It may also be a configuration.

FIG. 5 is a perspective view showing a laser diode of an optical deflector according to a third embodiment of the present invention. Referring to FIG. 5, in this third embodiment, the diffraction grating 2b formed on the protective glass 1a of the laser diode 1 is
It is configured so that the plane of polarization of zero can be controlled. That is, when forming the diffraction grating 2b on the protective glass 1a,
By controlling the arrangement direction of the diffraction grating 2b, it is possible to control the plane of polarization of the laser beam 100.

As described above, according to the embodiments of the present invention, the structure of the device becomes compact, and the conventional problems of increasing the size and price of the device can be solved.

[Effects of the Invention] As described above, according to the present invention, a laser beam is emitted by a semiconductor laser, the semiconductor laser is modulated by a modulation circuit, and the laser beam emitted from the semiconductor laser is diffracted by a diffraction grating. Since laser beam scanning is performed without complicating the structure of the device, it has become possible to provide an optical deflector that can reduce the size and cost of the device.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of an optical deflector according to an embodiment of the present invention, FIG. 2 is a schematic diagram for explaining the deflection principle of the diffraction grating shown in FIG. 1, and FIG. FIG. 1 is a graph for explaining the relationship between wavelength and oscillation intensity of the laser diode shown in FIG. 4, a perspective view showing a laser diode of an optical deflector according to a second embodiment of the present invention, and FIG. A perspective view showing a laser diode of an optical deflector according to a third embodiment of the present invention, FIG. 6A is a schematic diagram for explaining the principle of an optical deflector using a conventional galvanometer, and FIG.
Figure A is a perspective view showing an optical deflector capable of deflecting in the X-Y axis directions using a galvanometer, Figure 7 is a perspective view showing an optical deflector using a conventional polygon mirror, and Figure 8 1 is a schematic diagram showing an optical deflector using a conventional acousto-optic element. In the figure, 1 is a laser diode, 1a is a protective glass, 2.2a, 2b are diffraction gratings, 3 is a light shielding plate, 4 is a modulation circuit, 4a is a variable resistor, 4b is a power supply, 100 is a laser beam, 101 is 0 The secondary light 102 is the primary light. In each figure, the same reference numerals indicate the same or corresponding parts. Figure 4: Buddha statue, rice field diagram

Claims (3)

[Claims] (1) A laser deflector including: a semiconductor laser for emitting laser light; a modulation circuit for modulating the semiconductor laser; and a diffraction grating for diffracting the laser light emitted from the semiconductor laser. (2) The laser deflector according to claim 1, wherein the diffraction grating is provided at an exit window of the semiconductor laser. (3) The laser deflector according to claim 2, wherein the diffraction grating controls the plane of polarization of the light by controlling the direction in which the diffraction grating is arranged.