JP2001013417A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constantly control the quantity of light used for scanning an object even when the light quantity of a light source is changed and to constantly control the scanning range of the light even when the characteristic of a scanning means is changed or the scanning range of the light is optionally set without storing the large amount of data. SOLUTION: A laser beam emitted from a semiconductor laser 10 is reflected on the mirror 211 of a resonance scanner 210 and made incident on a PSD (position detection element) 220. By a light quantity and beam deflection width detection circuit 230, a light quantity detection signal and a beam deflection width detection signal are outputted from a current outputted by the PSD 220. By a light quantity control circuit 240, the laser 10 is controlled so that the quantity of the light received by the PSD 220 becomes constant in response to the light quantity detection signal. By a beam deflection width control circuit 250, a self-excited oscillation circuit 200 is controlled so that beam deflection width in the light receiving area of the PSD 220 becomes constant in response to the beam deflection width detection signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical scanning device for scanning an object with light.

[0002]

2. Description of the Related Art A laser scanning confocal microscope, a laser marker, a laser printer and the like are provided with an optical scanning device for scanning an object with light. For example, a resonance scanner is used in such an optical scanning device.

A resonance scanner is driven by a drive signal generated from a self-excited oscillation circuit, and vibrates (oscillates) a mirror around an axis. In such a resonance scanner, the vibration of the mirror resonates with the drive signal generated from the self-excited oscillation circuit. Therefore, the mirror can be vibrated at high speed by increasing the frequency of the drive signal.

An optical scanning device using a resonance scanner irradiates a mirror with light while vibrating the mirror, thereby making it possible to reciprocally scan the object with the reflected light. A laser scanning confocal microscope receives reflected light from an object while scanning the object with light within a certain scanning range using an optical scanning device, samples data based on the amount of received light, and converts the sampled data into data. The image of the object is displayed based on the object. In a laser marker or a laser printer, a light source is turned on or off based on image data while an object is scanned with light by an optical scanning device in a predetermined scanning range, and printing is performed on the object.

[0005]

In the above-described optical scanning device, when the light amount of the light source fluctuates due to a change in ambient temperature or a temporal change in the light source, the amount of light scanned on the object fluctuates. As a result, in the confocal microscope, the amount of reflected light from the object fluctuates, which hinders accurate measurement. In a laser marker or a laser printer, the amount of light for scanning an object fluctuates, and printing with a uniform density is prevented.

Further, when the deflection angle of the mirror of the resonance scanner fluctuates due to a change in ambient temperature or a change over time in the resonance scanner, the light scanning range of the object changes.

[0007] As a method of controlling the light scanning range on the object to be constant, a mask having an opening corresponding to the light scanning range is arranged between the light source and the light receiving element, and the light source is passed through the opening of the mask. There has been proposed a method in which light emitted from a device is scanned by a light receiving element. In this method, the swing width of the mirror is detected based on the time when light crosses both ends of the opening of the mask, and the swing width is controlled to a predetermined value. However, according to this method, when changing the scanning range of light, it is necessary to prepare another mask having an opening corresponding to the scanning range. In order to arbitrarily set the light scanning range, a plurality of masks having different openings for each light scanning range are required. Therefore, it is difficult to arbitrarily set the light scanning range.

In order to correct a change in the scanning range of light due to a change in ambient temperature, a method has been proposed in which the temperature near the resonant scanner is measured, and the frequency of the drive signal is controlled based on the measured temperature. ing. However, according to this method, it is necessary to previously store the frequency of the drive signal corresponding to each temperature in a memory or the like. Further, when the characteristics of the individual resonance scanners vary, the frequency of the drive signal cannot be accurately controlled.

Further, there has been proposed a method of detecting a scanning position of light scanned on an object and reading data to be displayed on a screen or data to be printed from a memory based on the detected scanning position. However, according to this method, it is necessary to store extra data in the memory in addition to the data to be displayed on the screen or the data to be printed.

An object of the present invention is to provide an optical scanning device capable of controlling the amount of light to scan an object even when the light amount of a light source changes, without storing a large amount of data. is there.

Another object of the present invention is to control the amount of light to scan an object even when the light amount of a light source changes, without storing a large amount of data, and to maintain the characteristics of the scanning means. It is an object of the present invention to provide an optical scanning device capable of controlling the light scanning range of an object to be constant even when the light amount changes or the light scanning range is arbitrarily set.

[0012]

Means for Solving the Problems and Effects of the Invention (1)
An optical scanning device according to a first aspect of the present invention is an optical scanning device that scans an object with light, and includes a light source that emits light, a mirror that reflects the light emitted by the light source, and a mirror. Scanning means for scanning the object with light reflected by the mirror, a scanning drive circuit for driving the rocking means of the scanning means, and at least light reflected by the mirror of the scanning means. A light receiving element that partially receives light, a light quantity detection circuit that detects an amount of light scanned by the scanning means from an output signal of the light receiving element, and a light quantity that is scanned by the scanning means in response to an output signal of the light quantity detection circuit. A light amount control circuit that feedback-controls the light source by the first control signal so that the light amount becomes constant; a scanning range detection circuit that detects a scanning range of light by the scanning unit from an output signal of the light receiving element; Run in response to output signal And a scanning range control circuit that performs feedback control of the scanning drive circuit with a second control signal so that the scanning range of the light by the inspection means is constant.

In the optical scanning device according to the present invention, the swing means of the scanning means is driven by the scan drive circuit, and the mirror is swung. The light emitted by the light source is reflected by a mirror of the scanning means and is scanned on the object.

At least a part of the light reflected by the mirror of the scanning means is received by the light receiving element. The amount of light scanned is detected from the output signal of the light receiving element, and the light source is feedback-controlled by the first control signal so that the amount of light scanned is constant. The scanning range of the light is detected from the output signal of the light receiving element, and the scanning drive circuit is feedback-controlled by the second control signal so that the scanning range of the light becomes constant.

Therefore, even when the light amount of the light source changes due to temperature fluctuation or temporal change, the amount of light scanned on the object can be controlled to be constant. In addition, even when the characteristics of the scan driving circuit change due to temperature fluctuation or aging, or when the scanning range of light is set arbitrarily,
The scanning range of light on the object can be controlled to be constant. In this case, it is not necessary to store a large amount of data.

(2) Second invention An optical scanning device according to a second invention is the optical scanning device according to the first invention, wherein the light source, the scanning means, the light receiving element, and the light amount detection are performed during the off period of the light source. A first switch for opening a first loop formed by the circuit and the light amount control circuit, and a scan driving circuit, a scanning unit,
A second switch for opening a second loop formed by the light receiving element, the scanning range detection circuit, and the scanning range control circuit, and a first control signal of the light amount control circuit when the first switch is turned off. The semiconductor device further includes a first holding circuit and a second holding circuit that holds a second control signal of the scanning range control circuit when the second switch is turned off.

In this case, during the off period of the light source, a first loop formed by the light source, the scanning means, the light receiving element, the light amount detection circuit and the light amount control circuit is opened by the first switch, and the feedback control of the light source is performed. Is stopped.
At this time, the first control signal is held by the first holding circuit. Thereby, when the light source shifts to the ON state, the first control signal smoothly shifts to the feedback control of the light source, and the feedback control is quickly stabilized.

In the off period of the light source, a scanning drive circuit,
A second loop formed by the scanning unit, the light receiving element, the scanning range detection circuit, and the scanning range control circuit is opened by the second switch, and the feedback control of the scanning unit is stopped. At this time, the second holding circuit
Are held. Thereby, when the light source shifts to the ON state, the second control signal smoothly shifts to the feedback control of the scanning unit, and the feedback control is quickly stabilized.

(3) Third Invention An optical scanning device according to a third invention is an optical scanning device for scanning an object with light, and comprises a light source for emitting light, and a light source for reflecting light emitted by the light source. Scanning means for scanning the object with light reflected by the mirror, a scanning drive circuit for driving the swinging means of the scanning means, and the mirror of the scanning means A light-receiving element that receives at least a part of the light reflected by the light-receiving element;
A light amount control circuit for feedback-controlling the light source by a control signal so that the amount of light scanned by the scanning unit in response to an output signal of the light amount detection circuit; The switch includes a switch for opening a loop constituted by the element and the light amount detection circuit, and a holding circuit for holding a control signal of the light amount control circuit when the switch is turned off.

In the optical scanning device according to the present invention, the swinging means of the scanning means is driven by the scanning drive circuit, and the mirror is swung. The light emitted by the light source is reflected by a mirror of the scanning means and is scanned on the object.

At least a part of the light reflected by the mirror of the scanning means is received by the light receiving element. The amount of light to be scanned is detected from the output signal of the light receiving element, and the light source is feedback-controlled by a control signal so that the amount of light to be scanned is constant. Therefore, even when the light amount of the light source changes due to a temperature change or a temporal change, the amount of light scanned on the target can be controlled to be constant. In this case, there is no need to store a large amount of data.

In the off period of the light source, a loop constituted by the light source, the scanning means, the light receiving element, the light amount detection circuit and the light amount control circuit is opened by a switch, and the feedback control of the light source is stopped. At this time, the control signal is held by the holding circuit. Thereby, when the light source shifts to the ON state, the control signal smoothly shifts to the feedback control of the scanning unit, and the feedback control is quickly stabilized.

(4) Fourth invention An optical scanning device according to a fourth invention is the optical scanning device according to any one of the first to third inventions, wherein the light reflected by the mirror of the scanning means is provided. It further comprises a branching means for branching a part and leading to a light receiving element.

In this case, a part of the light reflected by the mirror of the scanning means is branched by the branching means and guided to the light receiving element.
Thereby, the light source is feedback-controlled so that the amount of light to be scanned becomes constant. Since the feedback control is performed using the light source for causing the object to scan with light, accurate control is possible, and an increase in the number of components is suppressed.

(5) Fifth Invention An optical scanning device according to a fifth invention is the optical scanning device according to any one of the first to third inventions, wherein the light source comprises an optical scanning light source and a control light source. A light source, wherein the scanning means reflects light emitted by the light source for light scanning on the surface of the mirror to scan the object, and reflects light emitted by the control light source on the back surface of the mirror to receive light. Lead to.

In this case, the light emitted from the light source for light scanning is reflected on the surface of the mirror and scans an object, and the light emitted from the light source for control is reflected on the back surface of the mirror and is transmitted to the light receiving element. Be guided. This allows the object to be scanned with a sufficient amount of light.

(6) Sixth invention An optical scanning device according to a sixth invention is the optical scanning device according to any one of the first to fifth inventions, wherein the light receiving element has a light receiving region of a predetermined width. The scanning means forms a light spot having a size larger than the width of the light receiving area of the light receiving element in the light receiving area of the light receiving element.

In this case, a light spot having a size larger than the width of the light receiving area of the light receiving element is formed in the light receiving area.
The alignment of the optical system becomes easy.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where an optical scanning device according to the present invention is applied to a confocal microscope will be described below.

FIG. 1 is a side view of a confocal microscope according to an embodiment of the present invention. As shown in FIG. 1, the confocal microscope 100 includes a pedestal 70 and an optical unit 80. The optical section 80 is detachably attached to the base 70. The pedestal 70 includes a front part 70a and a rear part 70b. On the upper surface of the front part 70a, a manual handle 31 for moving the support base 30 for supporting the object up and down is provided. Further, on both side surfaces of the front portion 70a, manual handles 32 for moving the support base 30 back and forth and left and right are provided. Further, the front and rear portions 7 of the front portion 70a
Handles 71a and 71b are provided on the back of Ob, respectively.

The optical section 80 includes an optical system mounting section 50 and an indirect mounting section 60. A revolver 53 to which the objective lenses 17a, 17b, 17c, 17d are attached is provided on the lower surface of the optical system mounting section 50. Revolver 5
By rotating 3, an objective lens used for observation can be selected.

A male connector 52a and a female connector 52b for transmitting electric signals to and from an external device are provided on the side of the optical system mounting section 50. Female connectors are connected to both ends of the cable for the male connector 52a. A male connector is connected to both ends of the cable for the female connector 52b.

The indirect mounting portion 60 includes a back plate 60a, a bottom plate 60b, and a pair of side plates 60c. A plurality of screw holes 65 are provided on side end surfaces of the back plate portion 60a and the bottom plate portion 60b, and a plurality of screw holes 6 are provided on side surfaces of the side plate portion 60c.
8. A pair of screw holes 67 are provided on the front end face of the bottom plate portion 60b. A plurality of screw holes (not shown) are provided on the back surface of the back plate portion 60a.

FIG. 2 is a perspective view showing an assembly structure of the optical system mounting section 50, the indirect mounting section 60, and the pedestal 70 of the confocal microscope 100 of FIG.

As shown in FIG. 2, a plurality of screw holes 51 are provided on the bottom surface of the optical system mounting section 50. A plurality of through holes 61 are provided in the bottom plate portion 60b of the indirect mounting portion 60 so as to correspond to the plurality of screw holes 51. Through hole 6
A counterbore for accommodating the head of the mounting bolt is provided on the bottom side of 1.

The bottom plate portion 60b of the indirect mounting portion 60 includes
A recess 160 is provided to facilitate alignment between the through hole 61 and the screw hole 51. After the optical system mounting unit 50 is placed on the recess 160, the bolt 81 is screwed into the screw hole 51 through the through hole 61, so that the optical system mounting unit 50 and the indirect mounting unit 60 are integrated.

The bottom plate portion 60b of the indirect mounting portion 60
Are provided with a plurality of screw holes 62 and 63. A plurality of through holes 72 are formed in the pedestal 70 so as to correspond to the plurality of screw holes 62. The through holes 72 are located in grooves 83 extending from both side surfaces of the pedestal 70. Further, a concave portion 69 is formed in the back plate portion 60a of the indirect mounting portion 60. The back plate portion 60a is provided with a plurality of through holes 64 vertically penetrating from the inside of the concave portion 69 to the bottom surface. The pedestal 70 is provided with a plurality of objective lens mounting holes 74 so as to correspond to the plurality of through holes 64.

In the pedestal 70, alignment of the screw hole 62 of the indirect mounting portion 60 with the through hole 72 of the pedestal 70 and alignment of the through hole 64 of the indirect mounting portion 60 with the objective lens mounting hole 74 of the pedestal 70 are performed. A recess 170 is provided for ease. After placing the indirect mounting portion 60 integrated with the optical system mounting portion 50 on the concave portion 170, the bolt 82 is screwed into the screw hole 62 through the through hole 72, and the bolt 84 is inserted into the objective lens mounting hole through the through hole 64. 74. Thereby, the indirect mounting part 60 and the optical system mounting part 50 are fixed to the pedestal 70.

FIG. 3 is a schematic configuration diagram showing an example of an optical system mounted on the optical system mounting section 50 of the confocal microscope 100 of FIG.

As shown in FIG. 3, the optical system mounting section 50 includes
A laser optical system 1 and a white light optical system 2 are provided.

The laser optical system 1 is a confocal optical system,
A semiconductor laser 10 that emits, for example, red laser light L1 is provided as a light source. The semiconductor laser 10 is driven by a laser drive circuit 44 and emits a laser beam L1. After the laser beam L1 has passed through the first collimating lens 11,
Reflected by the beam splitter 12, the 1/4 wavelength plate 1
3, horizontal direction deflection device 14a, beam splitter 26
3, vertical deflection device 14b, first relay lens 1
5, the second half mirror 23, the second relay lens 16
And the objective lens 17 through the first half mirror 22
It is led to. A support 30 is provided near the focal position of the objective lens 17. The laser light L1 is focused on the surface of the object W by the objective lens 17. The objective lens 17 in FIG. 3 is the same as the objective lens 17a, 17b, 17 in FIG.
c, 17d.

As will be described later, the beam splitter 263 converts the laser light from the horizontal deflecting device 14a into the direction of the vertical deflecting device 14b and the PSD (Position Detector: Pod).
sition Sensitive Light Detector).

The horizontal deflecting device 14a comprises a resonance scanner described later, and deflects the laser beam L1 in the horizontal direction indicated by an arrow X. The vertical deflecting device 14b is constituted by, for example, a mirror attached to one galvano scanner, and deflects the laser light L1 in the horizontal direction indicated by the arrow Y. Thereby, the surface of the target object W is two-dimensionally scanned with the laser beam L1. The horizontal deflecting device 14a
Will be described later.

The support table 30 can be moved up and down by a manual handle 31 as indicated by an arrow Z, and can be moved by a manual handle 32 in the directions of arrows X and Y.

The laser beam L1 reflected by the object W passes through the objective lens 17, the first half mirror 22, the second relay lens 16, the second half mirror 23, and the first relay lens 15, and again. Vertical deflection device 14b,
Beam splitter 263 and horizontal deflection device 14a
１ ／ wavelength plate 13 and beam splitter 12 via
To the image forming lens 18. The laser light L1 is
The light is condensed by the imaging lens 18, passes through the optical aperture 19 a having a pinhole, and enters the light receiving element 19 b.

The light receiving element 19b is composed of, for example, a photomultiplier or a photodiode. The light receiving element 19b photoelectrically converts the incident laser light L1 and converts it into an analog light quantity signal via a first amplifying circuit 19d via a first A / D converter. (Analog / digital converter) 41. Brightness information is output from the first A / D converter 41.

Next, luminance information obtained by the laser optical system 1 will be described. The light stop 19 a is provided at the focal position of the imaging lens 18. The pinhole of the optical diaphragm 19a is extremely small. Therefore, the laser light L
When 1 is focused on the object W, most of the laser light L1 passes through the pinhole of the optical aperture 19a.
The amount of light received by the light receiving element 19b is significantly increased. Conversely, if the laser beam L1 is not focused on the target object W, most of the laser beam L1 does not pass through the pinhole of the optical diaphragm 19a, so that the amount of light received by the light receiving element 19b is significantly reduced. Therefore, a bright image is obtained in a focused portion of the scanning region by the laser optical system 1, and a dark image is obtained in other portions. Since the laser optical system 1 is a confocal optical system using the monochromatic laser light L1, luminance information with excellent resolution can be obtained.

Next, the white light optical system 2 will be described.
The white light optical system 2 has a white light source 20 that emits white light L2, which is illumination light for color information, as a light source. The white light L2 emitted from the white light source 20 passes through the second collimating lens 21, is reflected by the first half mirror 22, and is condensed by the objective lens 17 at the same position as the scanning area of the laser light L1. Is done.

The white light L 2 reflected by the object W passes through the objective lens 17, the first half mirror 22 and the second relay lens 16, and further passes through the second half mirror 2.
3 and forms an image on the surface of the color CCD 24. That is, the color CCD 24 is disposed at a position conjugate to or close to the conjugate with the light stop unit 19a.

The color CCD 24 includes a CCD driving circuit 43
Driven by The output signal of the color CCD 24 is output to a second A / D converter (analog-to-digital converter) 42 via a CCD drive circuit 43 and a second amplifier circuit 43a as an analog color image pickup signal. Color imaging information is output from the second A / D converter 42.

By performing predetermined processing on the luminance information from the first A / D converter 41 and the color imaging information from the second A / D converter 42, a color video signal is obtained, and a color enlarged image is obtained. The image is displayed on the display device.

In the confocal microscope according to the present embodiment, the semiconductor laser 10 is turned on to obtain luminance information by the laser optical system 1, and then the white light source 20 is turned on and the white light optical system 2 is turned on.
To obtain color imaging information. In this case, it is necessary to turn off the semiconductor laser 10 when obtaining color imaging information by the white light optical system 2 so that the color imaging information obtained by the white light optical system 2 is not affected by the laser light.

FIG. 4 is a block diagram showing a schematic configuration of an optical scanning device including the horizontal deflection device 14a of FIG.

The optical scanning device shown in FIG.
4a, the laser drive circuit 44, the semiconductor laser 10, the beam splitter 263, the PSD 220, the light amount
It comprises a beam swing width detection circuit 230, a light quantity control circuit 240, and a beam swing width control circuit 250. The horizontal deflection device 14a includes a self-excited oscillation circuit 200 and a resonance scanner 210. The resonance scanner 210 is driven by a drive signal generated by the self-excited oscillation circuit 200, and swings (vibrates) the mirror 211 around the axis 211a.

The laser light emitted from the semiconductor laser 10 is reflected by the mirror 211 of the resonance scanner 210, and is split by the beam splitter 263 into the direction of the vertical deflecting device 14b shown in FIG. As the mirror 211 of the resonance scanner 210 swings, the laser beam is scanned in the horizontal direction indicated by the arrow X of the object W in FIG. 3 and the laser beam is scanned in the longitudinal direction of the light receiving area of the PSD 220.

The output currents I1 and I2 of the PSD 220 are supplied to a light quantity / beam swing width detection circuit 230. Light intensity /
The beam amplitude detection circuit 230 detects the light amount by calculating the output currents I1 and I2 of the PSD 220, and supplies a light amount detection signal V (+) to the light amount control circuit 240. In addition,
The beam swing width detection circuit 230 calculates a laser beam scanning range (hereinafter, referred to as a scanning range) by calculating the output currents I1 and I2 of the PSD 220.
This is called the beam deflection width. ) Is detected, and a beam swing width detection signal VK is supplied to the beam swing width control circuit 250.

The light quantity control circuit 240 is a light quantity detection signal V (+) provided from the light quantity / beam fluctuation width detection circuit 230.
, The laser drive circuit 44 is controlled so that the amount of light received by the PSD 220 becomes constant.

The beam fluctuation width control circuit 250 responds to the beam fluctuation width detection signal VK supplied from the light amount / beam fluctuation width detection circuit 230 so that the beam fluctuation width in the light receiving area of the PSD 220 becomes constant. The circuit 200 is controlled.

FIG. 5 is a circuit diagram showing a detailed configuration of the optical scanning device of FIG. In FIG. 5, a self-excited oscillation circuit 200
Is a preamplifier 201, a phase shifter 202 including a filter,
A variable gain amplifier 203 and a buffer 204 are included. The resonance scanner 210 has a drive coil 212 and a pickup coil 213. The preamplifier 201, the phase shifter 202, the variable gain amplifier 203, the buffer 204, and the drive coil 212 of the resonance scanner 210 are connected in order, and the pickup coil 2 of the resonance scanner 210 is connected.
13 is connected to the preamplifier 201.

The semiconductor laser 10 includes a laser driving circuit 44
Driven by The laser drive circuit 44 is supplied with a control signal LA for controlling on / off of the semiconductor laser 10. The semiconductor laser 10 is turned on at the time of measurement by the laser optical system 1 of FIG.
The semiconductor laser 10 turns off.

The laser light emitted from the semiconductor laser 10 is converted into parallel light by the lens 261 and enters the mirror 211 of the resonance scanner 210. The laser light reflected by the mirror 211 is converted into condensed light by the relay lens 262 and enters the beam splitter 263. A part of the converged light is reflected by the beam splitter 263, converted into parallel light again by the relay lens 264, and incident on the vertical deflection device 14b in FIG. The remaining condensed light that has entered the beam splitter 263 passes through the beam splitter 263 and enters the PSD 220, and is scanned in the light receiving area of the PSD 220 in the direction indicated by the arrow x as the mirror 211 of the resonance scanner 210 swings. You.

The power supply voltage Vc is applied to the common electrode of the PSD 220.
c is applied. The PSD 220 derives two output currents I1 and I2 according to the position of the laser light incident on the light receiving area.

The beam / vibration width detection circuit 230 includes a current / voltage conversion circuit 225, an addition / subtraction circuit 231 and a rectification circuit 2
34. The output currents I1 and I2 of the PSD 220 are provided to the current-voltage conversion circuit 225. Current-voltage conversion circuit 2
Reference numeral 25 converts the output currents I1 and I2 of the PSD 220 into voltages V1 and V2, respectively, and outputs them.

The addition / subtraction circuit 231 includes an adder 232 and a subtractor 233. The adder 232 adds the voltage V1 and the voltage V2 provided from the current-voltage conversion circuit 225, and outputs the result as a light amount detection signal V (+). Subtractor 23
3 is a voltage V1 given from the current-voltage conversion circuit 225
, And outputs a beam position detection signal V (−).

The light quantity detection signal V (+) output from the adder 232 of the addition / subtraction circuit 231 is supplied to the light quantity control circuit 240 via the switch 235. ON / OFF of the switch 235 is controlled by the control signal PH.

The light quantity control circuit 240 includes the reference voltage circuit 24
1 and a comparison integration circuit 242. Comparison and integration circuit 24
2 includes an operational amplifier 243, a capacitor 244, and a resistor 245. The operational amplifier 243 works as a comparison circuit, and the capacitor 244 and the resistor 245 work as an integration circuit.

The comparison and integration circuit 242 includes an addition / subtraction circuit 231
Is compared with the reference voltage Vr1 output from the reference voltage circuit 241, and the light amount control signal corresponding to the difference between the light amount detection signal V (+) and the reference voltage Vr1. Vfb1 is supplied to the laser drive circuit 44. The laser drive circuit 44 controls the light amount of the semiconductor laser 10 in response to the light amount control signal Vfb1.

On the other hand, the beam position detection signal V (−) output from the subtractor 233 of the addition / subtraction circuit 231 is supplied to the rectifier circuit 234. The rectifier circuit 234 rectifies the beam position detection signal V (-) and outputs a beam fluctuation width detection signal VK proportional to the beam fluctuation width.

The beam amplitude detection signal VK output from the rectifier circuit 234 is supplied to the beam amplitude control circuit 250 via the switch 236. ON / OFF of the switch 236 is controlled by the control signal BS.

The beam amplitude control circuit 250 includes a reference voltage circuit 251 and a comparison and integration circuit 252. The comparison and integration circuit 252 includes an operational amplifier 253, a capacitor 254, and a resistor 255. The operational amplifier 253 serves as a comparison circuit, and the capacitor 254 and the resistor 25
5 works as an integrating circuit.

The comparison / integration circuit 252 compares the beam swing width detection signal VK supplied from the rectifier circuit 234 with the reference voltage Vr2 given from the reference voltage circuit 251, and calculates the difference between the beam swing width detection signal VK and the reference voltage Vr2. The corresponding beam swing control signal Vfb2 is supplied to the variable gain amplifier 203 of the self-excited oscillation circuit 200.

In this embodiment, the semiconductor laser 10 corresponds to a light source, the resonance scanner 210 corresponds to a scanning unit, the self-excited oscillation circuit 200 corresponds to a scan driving circuit, and the PSD 220
Corresponds to a light receiving element. Further, the light quantity / beam fluctuation width detection circuit 230 corresponds to a light quantity detection circuit and a scanning range detection circuit, the light quantity control circuit 240 corresponds to a light quantity control circuit, and the beam fluctuation width control circuit 250 corresponds to a scanning range control circuit. Further, the switch 235 corresponds to the first switch, the switch 236 corresponds to the second switch, the capacitor 244 corresponds to the first holding circuit, and the capacitor 245 corresponds to the first holding circuit.
4 corresponds to a second holding circuit. Further, the beam splitter 263 corresponds to a branching unit.

Next, the operation of the optical scanning device of FIG. 5 will be described with reference to the timing chart of FIG.

When the control signal LA is at a high level, the laser drive circuit 44 turns on the semiconductor laser 10. When the control signal PH is at the high level, the switch 235 is turned on, and the semiconductor laser 10, the resonance scanner 210, the PS
D220, current / voltage conversion circuit 225, addition / subtraction circuit 23
1. A first closed loop including the light amount control circuit 240 and the laser drive circuit 44 is configured. Also, the control signal BS
Is at a high level, the self-excited oscillation circuit 200, the resonance scanner 210, the PSD 220, the current-voltage conversion circuit 22
5, a second closed loop including the addition / subtraction circuit 231, the rectifier circuit 234, and the beam swing width control circuit 250 is configured. Switches 235 and 236 are turned on and off simultaneously.

When the second closed loop is formed when the semiconductor laser 10 is off, the resonance scanner 21
The shake of the 0 mirror 211 is disturbed. Therefore, in the present embodiment, the switches 235 and 236 are turned off before the semiconductor laser 10 is turned off, and are turned on after the semiconductor laser 10 is turned on.

The output currents I1 and I2 of the PSD 220 are 180 ° out of phase with each other. In FIG. 6, the output current I1 is represented by a solid line, and the output current I2 is represented by a broken line. Here, the DC components of the output currents I1 and I2 are Ip, and the amplitude of the AC components is Iac. The DC components Ip of the output currents I1 and I2 change according to the amount of light in the light receiving region of the PSD 220, and the AC components of the output currents I1 and I2 change according to the incident position of light in the light receiving region of the PSD 220.

The output currents I 1 and I 2 of the PSD 220 are converted into voltages V 1 and V 2 by the current / voltage conversion circuit 225 and added by the adder 232 of the addition / subtraction circuit 231, thereby obtaining the light quantity detection signal V (+). Light amount detection signal V
The level of (+) is mIp. Here, m is a constant. The level of the light amount detection signal V (+) indicates the light amount received by the PSD 220.

The comparison / integration circuit 242 is connected to the semiconductor laser 10
Is turned on, a light amount control signal Vfb1 corresponding to the difference between the light amount detection signal V (+) and the reference voltage Vr1 output from the reference voltage circuit 241 is output.

When the level of the light quantity detection signal V (+) is lower than the reference voltage Vr1, the level of the light quantity control signal Vfb1 becomes high, and the laser drive circuit 44
0 light amount is increased. Conversely, when the level of the light quantity detection signal V (+) is higher than the reference voltage Vr1, the level of the light quantity control signal Vfb1 becomes lower, and the laser drive circuit 44
Reduces the light amount of the semiconductor laser 10. Thus, the feedback control by the first closed loop is performed so that the level of the light amount detection signal V (+) becomes equal to the reference voltage Vr1. As a result, the amount of light received by the PSD 220 is controlled to be constant.

In this case, by arbitrarily setting the reference voltage Vr1 output from the reference voltage circuit 241,
The amount of light received by D220 can be controlled to any value.

The output currents I1 and I2 of the PSD 220 are converted into the voltages V1 and V2 by the current / voltage conversion circuit 225, and the voltage V2 is subtracted from the voltage V1 by the subtractor 233 of the addition / subtraction circuit 231 to obtain the beam position detection signal V (- )
Is obtained. The amplitude of the beam position detection signal V (−) is k ·
2Iac. Here, k is a constant. Rectifier circuit 2
By rectifying the beam position detection signal V (-) by 34, a beam deflection width detection signal VK is obtained. The beam fluctuation width detection signal VK has a level proportional to the beam fluctuation width in the light receiving region of the PSD 220.

The comparison and integration circuit 252 compares the beam swing width detection signal VK with the reference voltage Vr2 output from the reference voltage circuit 251, and determines the beam swing width according to the difference between the beam swing width detection signal VK and the reference voltage Vr2. Outputs control signal Vfb2.

When the level of the beam fluctuation detection signal VK is lower than the reference voltage Vr2, the level of the beam fluctuation control signal Vfb2 increases. As a result, the gain of the variable gain amplifier 203 increases, and the amplitude of the drive signal output from the buffer 204 increases. As a result, the deflection angle of the mirror 211 of the resonance scanner 210 increases, and PS
The beam swing width in the light receiving area of D220 increases. When the level of the beam swing detection signal VK is higher than the reference voltage Vr2, the level of the beam swing control signal Vfb2 becomes low. As a result, the gain of the variable gain amplifier 203 decreases, and the amplitude of the drive signal output from the buffer 204 decreases. As a result, the deflection angle of the mirror 211 of the resonance scanner 210 decreases, and the beam deflection width in the light receiving area of the PSD 220 decreases.

As described above, the beam swing width detection signal V
Feedback control by the second closed loop is performed so that the level of K becomes equal to the reference voltage Vr2. As a result, the beam swing width in the light receiving region of the PSD 220 is controlled to be constant.

In this case, the beam swing width can be arbitrarily controlled by arbitrarily setting the reference voltage Vr2 output from the reference voltage circuit 251.

While the semiconductor laser 10 is off, the output currents I1 and I2 of the PSD 220 are both 0. As a result, the level of the light amount detection signal V (+) and the level of the beam position detection signal V (-) become 0.

When the control signals PH and BS go low, the switches 235 and 236 are turned off. Thereby,
The first and second closed loops are open. At this time, the capacitor 244 of the comparison and integration circuit 242 holds the level of the light amount control signal Vfb1 immediately before the switch 235 is turned off. The capacitor 254 of the comparison and integration circuit 252 holds the level of the beam swing width control signal Vfb2 immediately before the switch 236 is turned off.

Thereafter, when the switches 235 and 236 are turned on, feedback control by the first and second closed loops is performed. In this case, the light amount control signal Vfb1 immediately before the switch 235 is turned off is held in the capacitor 244 of the light amount control circuit 240, and the beam shake width control signal Vfb2 immediately before the switch 236 is turned off is held in the capacitor 254 of the beam shake width control circuit 250. Is held, when the switches 235 and 236 are turned on again, the smooth transition is made to the feedback control by the first and second closed loops, and the feedback control is quickly stabilized.

In the confocal microscope of this embodiment, the amount of light scanned on the object W is controlled to be constant even when the light amount of the semiconductor laser 10 changes due to a change in temperature or a change with time. This makes it possible to always obtain a uniform amount of reflected light from the object W. Further, the self-excited oscillation circuit 200 or the resonance scanner 2
Even when the characteristics of the reference numeral 10 change, the scanning range on the target object W can be controlled to be constant. Thereby, the object W can always be displayed at a uniform magnification. As a result, it is possible to accurately measure the object W.

FIG. 7 is a schematic block diagram showing another example of the configuration of the optical scanning device. In the optical scanning device of FIG. 7, the semiconductor laser 10a for optical scanning and the semiconductor laser 10 for control
b is provided.

The semiconductor laser 10a for optical scanning and the semiconductor laser 10b for control are driven by a laser driving circuit 44. The laser light emitted from the semiconductor laser 10a for optical scanning is reflected on the surface of the mirror 11 of the resonance scanner 10 and enters the vertical deflection device 14b shown in FIG. The laser light emitted from the control semiconductor laser 10 b is reflected by the back surface of the mirror 211 of the resonance scanner 210 and enters the PSD 220. Resonance scanner 210
The laser light reflected on the surface of the mirror 211 with the swing of the mirror 211 scans the object W shown in FIG. 3 in the horizontal direction indicated by the arrow X, and is reflected on the back surface of the mirror 211. Are scanned in the longitudinal direction of the light receiving area of the PSD 220.

The output currents I1 and I2 of the PSD 220 are supplied to a light quantity / beam swing width detection circuit 230. Light intensity /
The beam amplitude detection circuit 230 detects the light amount by calculating the output currents I1 and I2 of the PSD 220, and supplies a light amount detection signal V (+) to the light amount control circuit 240. In addition,
The beam amplitude detection circuit 230 detects the scanning range (beam amplitude) of the laser light by calculating the output currents I1 and I2 of the PSD 220, and supplies a beam amplitude detection signal to the beam amplitude control circuit 250.

The light quantity control circuit 240 is a light quantity detection signal V (+) given from the light quantity / beam fluctuation width detection circuit 230.
, The laser drive circuit 44 is controlled so that the amount of light received by the PSD 220 becomes constant.

The beam fluctuation width control circuit 250 responds to the beam fluctuation width detection signal VK supplied from the light amount / beam fluctuation width detection circuit 230 so that the beam fluctuation width in the light receiving region of the PSD 220 becomes constant. The circuit 200 is controlled.

In this example, the semiconductor laser 10a for optical scanning is
Corresponds to a light source for optical scanning, and a semiconductor laser 10b for control.
Corresponds to the control light source.

In the optical scanning device of this embodiment, the resonance scanner 21
All of the laser light reflected on the surface of the 0 mirror 211 is given to the vertical deflecting device 14b shown in FIG. 3 and further incident on the object W, so that the object W is scanned with a sufficient amount of light. be able to.

FIG. 8 is a diagram showing the relationship between the light receiving area of the PSD 220 and the beam spot of the laser beam. As shown in FIG. 8, the beam spot LB of the laser beam has an elliptical shape. The semiconductor laser 10 is arranged such that the major axis of the beam spot LB coincides with the width direction of the light receiving area 220a of the PSD 220. The major axis of the beam spot LB is set longer than the width of the light receiving area 220a of the PSD 220. This facilitates the alignment of the optical system.

In the above embodiment, PSD2 is used as the light receiving element.
Although 20 is used, a CCD (charge coupled device) may be used as the light receiving element. When a CCD is used as the light receiving element, the peak value of the light amount signal representing the light amount at each pixel of the CCD or the average value of the light receiving signals corresponding to all the pixels of the CCD is used as the light amount detection signal. Further, a time interval exceeding a predetermined light receiving amount of a light receiving signal corresponding to each pixel of the CCD is used as a beam swing width detection signal.

In the above embodiment, the resonance scanner 210 is used as the scanning means, but a galvanomirror may be used as the scanning means.

In the above embodiment, the case where the optical scanning device of the present invention is applied to a confocal microscope has been described.
The optical scanning device of the present invention can be applied not only to a confocal microscope but also to a laser marker or a laser printer. In this case, printing with uniform density and printing with uniform dimensions can be performed.

[Brief description of the drawings]

FIG. 1 is a side view of a confocal microscope according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an assembling structure of an optical system mounting unit, an indirect mounting unit, and a pedestal of the confocal microscope of FIG. 1;

FIG. 3 is a schematic configuration diagram illustrating an example of an optical system mounted on an optical system mounting section of the confocal microscope in FIG.

4 is a block diagram illustrating a schematic configuration of an optical scanning device including the horizontal deflection device of FIG. 3;

FIG. 5 is a circuit diagram showing a detailed configuration of the optical scanning device of FIG.

FIG. 6 is a timing chart for explaining the operation of the optical scanning device of FIG. 5;

FIG. 7 is a block diagram illustrating another example of the optical scanning device.

FIG. 8 is a diagram illustrating a relationship between a light receiving region of a PSD and a beam spot of a laser beam.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser optical system 2 White light optical system 10, 10a, 10b Semiconductor laser 44 Laser drive circuit 200 Self-excited oscillation circuit 203 Variable gain amplifier 210 Resonance scanner 211 Mirror 220 PSD 230 Light intensity / beam fluctuation width detection circuit 231 Addition / subtraction circuit 235, 236 Switch 234 Rectifier circuit 240 Light intensity control circuit 241,251 Reference voltage circuit 242 Comparison / integration circuit 250 Beam swing width control circuit 263 Beam splitter

Claims (6)

[Claims] An optical scanning device for scanning an object with light, comprising: a light source that emits light; a mirror that reflects light emitted by the light source; and a swinging unit that swings the mirror. Scanning means for scanning the object with the light reflected by the mirror; scanning drive circuit for driving the swing means of the scanning means; and at least a part of the light reflected by the mirror of the scanning means. A light receiving element for receiving light, a light quantity detection circuit for detecting an amount of light scanned by the scanning means from an output signal of the light receiving element, and a light scanned by the scanning means in response to an output signal of the light quantity detection circuit A light amount control circuit that feedback-controls the light source by a first control signal so that the amount of light becomes constant; a scanning range detection circuit that detects a scanning range of light by the scanning unit from an output signal of the light receiving element; A scanning range control circuit that feedback-controls the scanning drive circuit with a second control signal so that the scanning range of the light by the scanning unit becomes constant in response to an output signal of the scanning range detection circuit. Optical scanning device. 2. A first switch for opening a first loop formed by the light source, the scanning means, the light receiving element, the light quantity detection circuit, and the light quantity control circuit during an off period of the light source. A second switch for opening a second loop formed by the scan drive circuit, the scan means, the light receiving element, the scan range detection circuit, and the scan range control circuit during an off period of the light source; A first holding circuit for holding the first control signal of the light quantity control circuit when the first switch is off; and a second control signal of the scanning range control circuit when the second switch is off. 2. The optical scanning device according to claim 1, further comprising: a second holding circuit for holding the data. 3. An optical scanning device that scans an object with light, comprising: a light source that emits light; a mirror that reflects the light emitted by the light source; and a rocking unit that rocks the mirror. Scanning means for scanning the object with the light reflected by the mirror; scanning drive circuit for driving the swing means of the scanning means; and at least a part of the light reflected by the mirror of the scanning means. A light receiving element for receiving light, a light quantity detection circuit for detecting an amount of light scanned by the scanning means from an output signal of the light receiving element, and a light scanned by the scanning means in response to an output signal of the light quantity detection circuit A light amount control circuit that feedback-controls the light source by a control signal so that the amount of light becomes constant; and the light source, the scanning unit, the light receiving element, and the light amount detection circuit during an off period of the light source. Optical scanning device comprising a switch for the-loop in an open state, further comprising a holding circuit for holding the control signal of the light amount control circuit when off of the switch. 4. The device according to claim 1, further comprising a branching unit that branches a part of the light reflected by the mirror of the scanning unit and guides the light to the light receiving element. Optical scanning device. 5. The light source includes a light source for light scanning and a light source for control, and the scanning means reflects the light emitted from the light source for light scanning on a surface of the mirror to scan the object. The optical scanning device according to any one of claims 1 to 3, wherein the light emitted by the control light source is reflected by a back surface of the mirror and guided to the light receiving element. 6. The light receiving element has a light receiving area of a predetermined width, and the scanning means forms a light spot having a size larger than the width of the light receiving area of the light receiving element in the light receiving area of the light receiving element. The optical scanning device according to claim 1, wherein: