JPH01213631A - Optical beam scanner - Google Patents

Abstract

PURPOSE:To attain scanning without using a movable part and to obtain a miniaturized and highly reliable optical beam scanner by utilizing a non-linear optical effect and executing optical beam scanning by opening/closing optical gates. CONSTITUTION:Plural phase conjugate elements are arranged in parallel along a scanning direction, a reflector 16 is arranged so that the reflecting face is opposed to the phase conjugate element group 10 and an optical control element 14 provided with plural optical gates is arranged between the reflecting face and the elements 10 along the scanning direction. Thereby, laser beams are successively oscillated along the scanning direction by successively opening/ closing the optical gates. Consequently, laser beam scanning can be attained, the reliability of the device can be improved by removing a movable part and the device can be miniaturized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a light beam scanning device, and particularly to a light beam scanning device of a light beam recording device that records information such as characters on a recording material by scanning a light beam. Regarding.

[Conventional technology]

A light beam recording device that records information such as characters on a recording material using a light beam is, for example, a heat mode recording device such as a laser direct recording film (LDF) that scans a laser beam modulated based on computer output information. 2. Description of the Related Art A laser computer output microfilmer (laser comb) that directly records information such as characters on a recording material made of a material is known (Japanese Patent Application Laid-Open No. 55-67722). The optical beam scanning device of this laser comb consists of a rotating polygon mirror that deflects a laser beam emitted from an argon laser and modulated according to character information, etc. in the main scanning direction, and a rotating polygon mirror that deflects the reflected light from the rotating polygon mirror in the sub scanning direction. The recording material is composed of a galvanometer equipped with a deflection mirror, and a rotating polygon mirror and a galvanometer scan a laser beam onto a recording material through a scanning lens to record information such as characters.

[Problem that the invention seeks to solve]

However, the optical beam scanning device using the rotating polygon mirror and the galvanometer has a problem in that the precision deteriorates over time due to wear and the like of the movable part since there is a movable part. In addition, a rotating polygon mirror is rotated by a motor at a constant rotation speed to deflect the laser beam in the main scanning direction, and the mirror surface is tilted by the tilt of the motor axis, etc., so this tilt of the mirror surface causes unevenness in the sub-scanning direction. There is a problem in that a correction optical system is required to prevent this unevenness, which increases the size of the apparatus.

The present invention has been made to solve the above problems,
An object of the present invention is to provide a light beam scanning device in which the reliability is improved and the device is miniaturized by performing scanning using a phase conjugate element, thereby improving the reliability of the movable part.

[Means for solving problems]

In order to achieve the above object, the present invention includes a phase conjugate element group consisting of a plurality of phase conjugate elements arranged in parallel along the scanning direction, and a pumping light beam for exciting the plurality of phase conjugate elements. a light source system, a reflecting mirror arranged such that a reflecting surface faces the phase conjugate element group, and a plurality of light gates arranged in parallel along the scanning direction, and the phase conjugate element group and the reflecting mirror. and a control circuit that controls opening and closing of the optical gate.

[Effect]

The present invention uses multiple phase conjugate elements (phase conjugate mirrors) with nonlinear optical effects to generate phase conjugate by four-wave mixing, thereby scanning a light beam without using optical components such as a rotating polygon mirror or a galvanometer. It is something to do. When the phase conjugate element is excited by being irradiated with a pumping light beam, the phase conjugate element forms a resonator with a reflective surface existing in the vicinity of the phase conjugate element, and laser oscillation occurs between them. By this laser oscillation, a laser beam is oscillated along a straight line connecting the phase conjugate element and the reflecting surface. For this reason, in the present invention, a plurality of phase conjugate elements are arranged in parallel along the scanning direction to form a phase conjugate element group, and a reflecting mirror is arranged so that the reflecting surface faces this phase conjugate element group. A light control element including a plurality of light gates arranged in parallel along the scanning direction is arranged between the surface and the phase conjugate element. If this optical gate is closed, no resonator is formed between the reflecting surface and the phase conjugate element, so no laser beam is generated. The phase conjugate element corresponding to the opened optical gate comes to face each other, thereby forming a resonator and causing laser oscillation. Therefore, by sequentially opening the optical gates, the laser beam is sequentially oscillated along the scanning direction, thereby making it possible to scan the laser beam.

〔Effect of the invention〕

As explained above, according to the present invention, since the light beam is scanned by using the nonlinear optical effect and by opening and closing the light gate, scanning can be performed without using a movable part. The effect is that a highly reliable optical beam scanning device can be provided.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings. As shown in Figure 1, barium titanate (B a
n cubic phase conjugate elements 100.10-. 103...10 are arranged in parallel at regular intervals along the main scanning direction to form a phase conjugate element group 10. A plane mirror 12 and a beam splitter 18 are arranged so as to sandwich the phase conjugate element group 10 therebetween. A laser oscillator 20 is arranged near the beam splitter 18 so that the laser beam is incident on the beam splitter at an incident angle of 45 degrees. The laser beam oscillated from the laser oscillator 20 is reflected by the beam splitter 18 and transmitted to the phase conjugate element 10. is incident on the A part of this incident laser beam is transmitted to the phase conjugate element 1
0. However, the remaining laser beam is absorbed by each phase conjugate element and passes through the phase conjugate elements 100, 102, .
・・１０． , reaches the plane mirror 12, is reflected by the plane mirror 12, and enters the phase conjugate element 101 again,
Phase conjugate element 10. , 10h-, . Then, the laser beam incident on the phase conjugate element group 10 from the beam splitter 18 and the laser beam incident on the phase conjugate element group 10 from the plane mirror 12 become two bombing light beams, and each phase within the phase conjugate element group 10 is The conjugated element absorbs the energy of this pumping light beam and is excited.

Further, the plane mirror 16 and the recording material 22 are arranged in parallel so as to sandwich the phase conjugate element group 10, and the light control element 14 is arranged between the phase conjugate element 10 and the plane mirror 16 so as to be parallel to the plane mirror 16. has been done. The reflective surface of the plane mirror 16 is arranged to face the phase conjugate element 10. The recording material 22 is conveyed at a constant speed in the sub-scanning direction (direction perpendicular to the paper surface of FIG. 1) by a driving device 38.

Note that C is the optical axis of the phase conjugate element.

As shown in FIG. 2, the light control element 14 includes a polarizer 30,
The analyzer 32 is arranged so that its polarization plane forms an angle of 90° with the polarization plane of the polarizer 30, and the PLZT ((Pb, La) (ZrSTi) is arranged between the polarizer 30 and the analyzer 32.
)03) A substrate 34. The PLZT substrate 34 has a plurality of electrodes...Eh-+, Ek% Ek
i+... are arranged at equal intervals. This electrode can be composed of an alloy of Au and Cr or In2O,
Each of them is connected to a drive circuit 24 so that a voltage can be applied independently. This light control element 14 is arranged with a phase conjugate element 10 and a plane mirror 16 so that the arrangement direction of the electrodes is along the main scanning direction.
is located between. Polarizer 30 of light control element 14
When a light beam is irradiated from the side, it is transmitted through the polarizer 30 to become linearly polarized light, and then is irradiated onto the PLZT substrate 34 . At this time, when a voltage is applied to adjacent electrodes of the PLZT substrate 34, the light beam transmitted between the electrodes of the PLZT substrate 34 undergoes a phase change proportional to the square of the electric field and becomes elliptically polarized light. This elliptically polarized light is irradiated onto the analyzer 32, and the analyzer 32
Only components that match the polarization plane of 2 pass through the analyzer 32. As a result, the space between the electrodes acts as a light gate, and the light gate to which no electric field is applied remains closed, but the light gate to which an electric field is applied is opened and connected to this light gate. The light beam will be transmitted through the corresponding portion.

When the optical gate is opened as described above, the portion of the plane mirror 16 corresponding to the optical gate and the phase conjugate element 10 face each other to form a resonator, and connect the above portion of the plane mirror 16 and the phase conjugate element 10. A laser beam is oscillated in a straight line and focused on the recording material 22 to enable recording. In this way, since recording is performed by a laser beam that passes through optical gates formed by adjacent electrodes, the number of optical gates is made equal to the total number of dots that can be recorded in one line in the main scanning direction - ( Since the number of electrodes is n, n-1
). Therefore, the number of electrodes is one more than the number of dots.

The drive circuit 24 is connected to a control circuit 26.

A pulse oscillator 28 is connected to the control circuit 26 so that a pulse signal consisting of a pulse train generated at predetermined intervals is manually input. This pulse signal is input to a dot signal generator 36 which converts character information output from the computer into a dot signal, and the dot signal generator 36 uses the pulse signal as a synchronization signal to convert the character information into a dot signal.

Next, a routine for controlling the drive circuit 240 by the control circuit 26 will be explained. FIG. 3 shows an interrupt routine that is interrupted by the rising edge of the pulse signal input from the pulse oscillator 28 immediately after the start of sub-scanning, and shows step 1.
00, the pulse number P initialized to 0 is incremented, and then in step 102, this pulse number P becomes the maximum value P of the pulse numbers. It is determined whether or not the value has exceeded AX. The number of pulses P is the maximum value P. When the number of pulses exceeds AX, the number of pulses P is set to 1 in step 104. The maximum value P1 of this number of pulses. lAX is set equal to the total number of electrodes provided on the PLZT substrate 34.

FIG. 4 shows the main routine, step 110.
It is determined whether or not a dot signal is input. When the tod signal is manually operated, step 11
At step 2, the number of pulses P counted in the interrupt routine of FIG. 3 is read, and at step 114, P, P+1
Apply voltage to the second electrode. As a result, the Pth electrode E and the P+1th electrode E. The optical gate between the recording material 1 and the recording material 2 is opened, and the laser beam enters the recording material 2 as explained above.
A beam spot having a size of several μm is focused on the beam spot 2, and a dot is recorded on the recording material.

FIG. 5 is a diagram showing the correspondence among the pulse signal, pulse number P1 dot signal, and voltage application electrode when controlled as described above. When the number of pulses P is 2, when a dot signal for recording dots is input, voltage is applied to the 2.3rd electrode, and when the number of pulses is 4.5, the voltage is applied to the 4.5th and 5th electrodes, respectively. .The state in which a voltage is applied to the sixth electrode is shown.

As described above, according to this embodiment, although it is necessary to convey the recording material for sub-scanning, main scanning can be performed without using any movable parts.

Note that the above example explained an example of recording information on a recording material by applying a voltage to adjacent electrodes, but when using a heat mode recording material etc. as the recording material, a high-power laser beam is required. As shown in FIG. 6, a region including a plurality of adjacent electrodes may be used as one optical gate to obtain a high-power laser beam. In this case, it is preferable to use a transparent electrode as the electrode.

Next, another embodiment of the present invention will be described with reference to FIG.

In this embodiment, a plurality of phase conjugate elements 1 are arranged along the main scanning direction.
0. ,． 10□1...10. , , are arranged in parallel to form a phase conjugate element array, and by arranging a plurality of phase conjugate element arrays in parallel along the sub-scanning direction, the phase conjugate elements 1008, 1021...10. , , are arranged in a grid to form a phase conjugate element group. In order to excite this phase conjugate element group, a beam splitter 18.corresponding to the phase conjugate element array is used. ．． 18□ ...18.
, and one laser oscillator 20 is used to irradiate each phase conjugate element array with a pumping light beam as in the above embodiment.

As shown in FIG. 8, the light control element 14 of this embodiment has a plurality of electrodes E, . . . E2 . , E31, . . . E is provided with a PLZT substrate 34 arranged in a grid pattern. This light control element 14 is arranged between the phase conjugate element group shown in FIG. 7 and the plane mirror 16 so that the arrangement direction of the electrode row (horizontal direction in the figure) consisting of n electrodes is along the main scanning direction. Placed.

In this embodiment, main scanning is performed by sequentially applying voltages between adjacent electrodes in an electrode row, and sub-scanning is performed by sequentially changing the electrode rows to which voltages are applied.

In the above example, a plane mirror was used as the reflector because the distance from the reflector constituting the resonator to the recording material was short, so the attenuation of the laser beam was small, but a concave mirror was used as the reflector. It can also be used. In this case, it is preferable to curve the light control element and the recording material so that the concave mirror, the light control element, and the recording material are parallel to each other. Further, although an example in which a scanning lens is not used has been described above, a scanning lens may be formed by arranging a plurality of microlenses between the phase conjugate element and the recording material so as to correspond to each of the optical gates. In conventional light beam scanning devices, scanning is performed using a rotating polygon mirror or a galvanometer, which requires an expensive lens with distortion such as an fθ lens or an arcsine lens as a scanning lens. Since the lens only needs to have the function of converging light, it is easy to manufacture. In addition,
Although the above description has mainly been about a light beam scanning device for a laser comb, the present invention is not limited thereto and can also be applied to storage on an optical disk.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an embodiment of the present invention, Fig. 2 is an exploded perspective view showing a part of the light control element, Fig. 3 is a flowchart showing a pulse rising interrupt routine, and Fig. 4 is a flowchart showing the pulse rising interrupt routine. A flowchart showing the main routine for controlling the application; Fig. 5 is a diagram showing the relationship between the pulse signal, number of pulses, and dot signal; Fig. 6 is a diagram showing the relationship between the pulse signal, the number of pulses, and the dot signal.
The figure is a line diagram showing another example of the light gate of the above embodiment, Fig. 7 is a schematic diagram showing another embodiment of the present invention, and Fig. 8 is a divided perspective view of the light control element of the above embodiment. It is. DESCRIPTION OF SYMBOLS 10... Phase conjugate element group, 12... Plane mirror, 14... Light control element, 16... Plane mirror, 20... Laser oscillator, 22... Recording material.

Claims (1)

[Claims] (1) a phase conjugate element group consisting of a plurality of phase conjugate elements arranged in parallel along the scanning direction; a light source system that irradiates a pumping light beam for exciting the plurality of phase conjugate elements; A light beam comprising a reflecting mirror arranged to face the phase conjugate element group, and a plurality of light gates arranged in parallel along the scanning direction, and arranged between the phase conjugate element group and the reflecting mirror. A light beam scanning device including a control element and a control circuit that controls opening and closing of the light gate.