JPH05127109A - Device and method for controlling amplitude of vibrating optical element - Google Patents

Abstract

PURPOSE:To accurately control the amplitude of a resonant mirror and to easily plural amplitudes. CONSTITUTION:The device which controls the amplitude of the vibrating optical element emitting an incident light beam is equipped with a mask 7 where the light beam emitted by the vibrating optical element is made incident and which is arranged to width corresponding to the amplitude to be controlled, a detector 8 which receives the light beam passed through the mask 7 and detects the time intervals of variation in the quantity of light at both ends of the mask 7. Then the detected time intervals are compared with accurate previously found reference time and corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amplitude control device and a control method for an oscillating optical element such as a resonant mirror which oscillates and outputs an incident light beam.

[0002]

2. Description of the Related Art As a conventional technique for controlling the amplitude of a vibrating optical element that vibrates and emits an incident light beam, there is, for example, one shown in FIG. 6 or 7. Both
Since the characteristics of the vibrating optical element vary depending on various conditions such as temperature, a means for correcting this is provided.

FIG. 6 shows that the sine wave output from the sine wave generation circuit 17 is amplified by an amplification circuit 19 having a variable amplification factor, and is corrected with an appropriate amplification factor. Mirror drive circuit 20 after being amplified
Is converted into a driving output, the resonant mirror 22 is vibrated and driven by the mirror driving circuit 20, and the light incident on the resonant mirror 22 from a light source (not shown) is reflected while vibrating at an amplitude according to the vibration angle of the resonant mirror 22.

The amplification factor of the amplification circuit 19 is the amplification factor control circuit 1
8, the amplification factor control circuit 18 determines the amplification factor of the amplification circuit 19 so that the resonant mirror 22 oscillates as stably as possible in accordance with changes in conditions such as temperature.

FIG. 7 shows a resonant mirror 27.
The spot light is radiated onto the target, the amplitude of the reflected wave is detected, and the detection result is corrected.

That is, the sine wave output from the sine wave generation circuit 23 is amplified by an amplification circuit 24 having a variable amplification factor, amplified by an appropriate amplification factor, and then converted into a drive output by a mirror drive circuit 25, and then a resonant mirror. 27 is oscillated and driven, and the light incident on the resonant mirror 22 from the light source 28 of the spot light is reflected while vibrating at an amplitude according to the vibration angle of the resonant mirror 27.

Scanning end detection detectors 29 and 30 are arranged at both ends of the amplitude of the reflected light to be set, and the comparison circuits 31 and 32 receiving the outputs of the scanning end detection detectors 29 and 30 compare the signal strength with the set value. Output to the CPU 33,
The CPU 33 controls the amplifier circuit 24 to have an appropriate amplification factor with reference to the outputs of the comparison circuits 31 and 32.

[0008]

However, in such a conventional technique, in the former case in which the amplification factor is corrected by a predetermined amplification factor, the accuracy of setting the amplification factor of the amplification circuit 19 which is predetermined with respect to a change in conditions is set. It is difficult to raise the amplitude, and the amplitude of the resonant mirror 22 is not exactly set with respect to the control signal, resulting in poor control accuracy.

Further, in the latter in which the scanning end detection detectors 29 and 30 are arranged at both ends of the amplitude, not only a minimum of two detectors are required, but also the amplitude setting is fixed, and the plurality of amplitudes are fixed. When setting it, a plurality of detectors must be arranged, and there is a problem that the arrangement of members is complicated and the processing is complicated.

The present invention has been made by paying attention to the problems of the prior art as described above, and it is possible to accurately control the amplitude of the resonant mirror and to easily set a plurality of amplitudes. It is an object to provide an amplitude control device and a control method for an optical element.

[0011]

The gist of the present invention for achieving the above object is an amplitude control device for a vibrating optical element that vibrates and emits one incident light beam. A mask (7, 7a) which is arranged corresponding to the amplitude to be controlled by the light beam emitted from the mask.
And a detector (8) for receiving a light beam that has passed through the mask (7, 7a) and generating an output signal in response to a change in the amount of light generated at both ends of the mask (7, 7a), and the detector (8).
3. An amplitude control device for an oscillating optical element, comprising: a timing circuit that detects the time interval of the output signal of 1. and means for controlling the amplitude of the signal optical element based on the detected time interval.

2. A method for controlling the amplitude of a vibrating optical element for oscillating and emitting an incident light beam, wherein a mask (7) is provided with a width corresponding to the amplitude to control the light beam emitted from the vibrating optical element. , 7a), and the mask (7, 7a) is transmitted through the light beam that has passed through the mask (7, 7a).
A method for controlling the amplitude of an oscillating optical element, characterized in that the time interval of the change in the amount of light occurring at both ends of is detected, and the time interval is compared with a previously determined reference time for correction.

[0013]

The vibrating optical element vibrates the incident light beam and emits it. The light rays emitted from the vibrating optical element are masks (7,
7a) and the mask (7, 7a) is arranged with a width corresponding to the amplitude to be controlled.
A change in the output characteristic of the light beam appears at both ends of a), and both ends of the mask (7, 7a) are detected, whereby the time interval of the output signal can be detected, and the time interval of this output signal is obtained in advance. It can be corrected to an accurate amplitude by comparing with a certain accurate reference time. It is extremely accurate because it directly monitors the amplitude of the vibrating optics. Even if the amplitude setting needs to be changed, it can be easily dealt with by replacing the mask (7, 7a) and changing the reference time.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a first embodiment of the present invention.

The amplitude control device appropriately maintains the amplitude of the vibrating optical element that vibrates the incident light beam and emits it.

The amplitude control device includes a sine wave generation circuit 1 for generating a sine wave having a resonance frequency of a resonant mirror 5 which is an oscillating optical element, and an amplification circuit 2 for receiving an output of the sine wave generation circuit 1 and having a variable amplification factor. A mirror drive circuit 4 that vibrates the resonant mirror 5 and a light source 6 that causes light to enter the resonant mirror 5. The light source 6 forms spot light for scanning on the resonant mirror 5 and makes it incident.

A mask 7 having a width corresponding to the amplitude to be controlled is disposed at a position where a light beam which is incident from the light source 6 to the resonant mirror 5 which is an oscillating optical element and is reflected and emitted. As shown in FIG. 2, the mask 7 is provided with transmissive portions 12 on both sides of a reflective portion (or a light shielding portion) 11, and the light source 6
2 is set so as to reciprocate in the horizontal direction in FIG.

Further, the detector 8 is arranged at a position for receiving the light beam that has passed through the mask 7, and the spot light 13 is applied to the mask 7.
Of the output signal of the detector 8 which shows the change in the light intensity when it crosses both ends of the reflection part 11 of the
And a control unit 10 for outputting a feedback signal of an amplification factor to the amplifier circuit 2 in comparison with an accurate reference time previously obtained on the basis of the time signal of the time counting circuit 9.

Next, the operation will be described.

The sine wave generating circuit 1 oscillates a sine wave having the resonance frequency of the resonant mirror 5, and the sine wave output from the sine wave generating circuit 1 is amplified by an amplifying circuit 2 with an appropriate amplification factor and then the mirror driving circuit 4 To enter. The mirror drive circuit 4 inputs an output suitable for driving the resonant mirror 5 to the resonant mirror 5, and the resonant mirror 5 as an oscillating optical element is oscillated by a sine wave at a resonance frequency. The light of the spot light 13 incident on the resonant mirror 5 from the light source 6 is reflected while vibrating at an amplitude according to the vibration angle of the resonant mirror 5.

Since the ray of the spot light 13 incident on the resonant mirror 5 is vibrated and emitted, the spot light 13 emitted from the resonant mirror 5 is incident on the mask 7 and deviates from both ends of the reflecting portion 11 of the mask 7. It vibrates while reciprocating in the horizontal direction in FIG. 2 up to the positions a1 and a2 of the transmitting portion 12. Since the reflecting portion 11 is arranged corresponding to the amplitude of the spot light 13 to be controlled, a change in the output characteristic of the light beam appears at both ends of the finally obtained amplitude. That is, as shown in FIG.
In the case of 1, the light beam of the spot light 13 does not reach the detector 8, and at the positions a1 and a2 of the transmission part 12, the light beam passes through the transmission part 12 and reaches the detector 8, so that intensity signals b2 and b3 are generated.

Both ends of the reflector 11 are detected by the intensity signals b2 and b3, and if the interval between the intensity signals b2 and b3 is timed by the timing circuit 9, the time interval which is the time when the light beam crosses the reflector 11 is detected. .. The control unit 10 which has obtained the crossing time information from the time counting circuit 9 compares the crossing time with a predetermined accurate reference time and outputs a feedback signal of the amplification factor to the amplification circuit 2. The amplifier circuit 2 is the control unit 1.
Adjust the amplification factor based on the feedback signal from 0,
Since the output of the sine wave generation circuit 1 is amplified with an appropriate amplification factor, the mirror drive circuit 4 can drive the resonant mirror 5 while correcting it so that the resonant mirror 5 vibrates with an accurate amplitude.

The amplitude of the resonant mirror 5 is directly monitored and maintains high accuracy. When it is necessary to change the amplitude setting, the mask 7 is replaced and the control unit 1
This is handled by changing the reference time for comparison with 0.

FIG. 3 shows a second embodiment of the present invention.

In this embodiment, for example, a mask for outputting a scanning clock signal for obtaining image information is set.

The mask 7a is a so-called grating, and is formed on the transmissive part 15 at a predetermined cycle.
This is a linear scale in which 4, 14, ... The spot light 16 is located at a position c outside of the reflecting portions 14, 14 ...
1 and c2 are set to vibrate.

In this embodiment, the spot light 16 is at the position c.
When vibrating with the amplitudes of 1 and c2, as shown in FIG.
Intensity signals d1 and d2 are generated at the positions corresponding to 1 and c2, and light rays are alternately reflected and transmitted in the reflecting portions 14, 14, ..., Therefore, scanning signals e, e. Scanning signal e,
Since e ... Is an accurate cycle, it is used for forming the scan clock signal. In the second embodiment, as in the first embodiment, the interval between the intensity signals d1 and d2 is timed and corrected so that the resonant mirror vibrates with the correct amplitude.

In the above embodiment, the mask which transmits at both ends of the amplitude is shown, but the reflection part and the transmission are arranged in reverse so that the reflection signal is used as the intensity signal for detecting the amplitude. It goes without saying that it is good. Further, the same mask as that of the embodiment may be used to detect the reflected light, or the reflective portion and the transmissive portion may be arranged in reverse to detect the transmitted signal.

[0029]

According to the amplitude control apparatus and the control method of the vibrating optical element according to the present invention, the light beam emitted from the vibrating optical element is made incident on the mask, and the light beam that has passed through the mask is received and is periodically reflected at both ends of the mask. Since the time interval of the change in the amount of light that occurs is controlled, the amplitude can be controlled with extremely high accuracy by directly monitoring and correcting the amplitude of the vibrating optical element. Since the structure is simple by combining the mask and the detector, the members can be easily arranged, and the amplitude can be easily changed by exchanging the mask.

[Brief description of drawings]

FIG. 1 is a block diagram showing an amplitude control device for a vibrating optical element according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a mask of the amplitude control device for the vibrating optical element according to the first embodiment of the present invention.

FIG. 3 is a plan view showing a mask of an amplitude control device for a vibrating optical element according to a second embodiment of the present invention.

FIG. 4 is a diagram showing an amplitude signal according to the first embodiment of the present invention.

FIG. 5 is a diagram showing an amplitude signal according to a second embodiment of the present invention.

FIG. 6 is a block diagram showing a first conventional example.

FIG. 7 is a block diagram showing a second conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sine wave generation circuit 2 ... Amplification normal path 4 ... Mirror drive circuit 5 ... Resonant mirror 6 ... Light source 7, 7a ... Mask 8 ... Detector 9 ... Timing circuit 10 ... Control part 11, 14 ... Reflection part 12, 15 ... Transmission part 13, 16 ... Spot light

Claims (2)

[Claims] 1. An amplitude control device for a vibrating optical element, which vibrates and outputs an incident light beam, wherein the light beam emitted from the vibrating optical element enters and is arranged corresponding to the amplitude to be controlled. A mask, a detector that receives a light beam that has passed through the mask and generates an output signal that responds to a change in the amount of light that occurs at both ends of the mask, a clock circuit that detects the time interval of the output signal of the detector, and the detected time interval. A means for controlling the amplitude of the signal optical element based on the above, and an amplitude control apparatus for a vibrating optical element. 2. A method for controlling the amplitude of a vibrating optical element for oscillating an incident light beam and emitting the vibrating optical element, the method comprising: a mask having a width corresponding to an amplitude to control the light beam emitted from the vibrating optical element. Vibratory optics characterized by detecting a time interval of a change in the amount of light generated at both ends of the mask through a light beam that has been incident and has passed through the mask, and comparing the time interval with a reference time determined in advance for correction. Element amplitude control method.