JP3140558B2 - Optical axis correction device for laser light - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam optical axis correction device suitable for use in a laser beam device such as a laser plotter for drawing a pattern using a laser beam.

[0002]

2. Description of the Related Art There is a laser plotter as an apparatus for drawing a pattern on a photosensitive material using a laser beam, and a laser beam emitted from a laser light source is converted into a polygon mirror, fθ
The surface of the photosensitive material is scanned by a scanning unit including a lens or the like, and a required pattern is drawn. In such a laser beam device, it is necessary to control the optical axis position of the laser beam in the scanning section with high precision in order to draw a pattern as designed, and therefore, the laser beam is conventionally provided in a part of the optical path of the laser beam. An axis correcting device is provided, which corrects the optical axis of the laser beam when the optical axis deviates from the reference position. For example, a half mirror is provided in a part of the optical path to split a part of the laser light, the split laser light is received by a position sensor, and the shift amount of the optical axis is detected based on the output value. Further, a drive mirror is provided in an optical path at a stage earlier than this, and the angle of the drive mirror is adjusted based on the detected shift amount of the optical axis to control the optical axis to the reference position.

[0003]

As described above, the conventional optical axis correcting device controls the optical axis position of the laser light at a position along the optical path. That is, although it is preferable that the optical axis position is controlled by the end position of the laser beam, a laser light device having a mechanism for scanning the laser beam at a high speed in a scanning section at the end position of the laser beam, such as a laser plotter. In such a case, since there is a restriction in arranging the position sensor for detecting the optical axis position at the terminal position, it is difficult to detect the optical axis position at the terminal position. For this reason, conventionally, the detection and correction of the optical axis are performed at an optical path position as close as possible to the end position.

However, even if the control of the position of the optical axis is performed in the middle of the optical path, the displacement of the optical axis at a later stage cannot be corrected. A shift occurs, which causes a problem that a pattern cannot be drawn as designed. In particular, in a laser plotter, a scanning unit is composed of a number of components such as a polygon mirror, an fθ lens, and a telecentric optical system, and these components are minutely deformed due to changes in temperature, humidity, air pressure, or the like, or a device base. Due to the above-mentioned minute fluctuation, the fluctuation of the position of the optical axis at the terminal end cannot be neglected, and the error in pattern drawing tends to be remarkable. SUMMARY OF THE INVENTION It is an object of the present invention to provide a laser beam optical axis correction device capable of controlling the optical axis position at the end position of the laser beam with high accuracy.

[0005]

SUMMARY OF THE INVENTION The present invention is directed to a driving mirror disposed on an optical path of a laser beam emitted from a laser light source and changing the optical path of the laser beam when driven, and a mirror for controlling the driving mirror. A drive unit, means for detecting the optical axis position of the laser light along the optical path, means for detecting environmental conditions such as the ambient temperature, humidity, and atmospheric pressure of the laser light device, and optical axis correction corresponding to changes in the environmental conditions Means for storing the quantity;
A control unit that reads a corresponding optical axis correction amount from the storage unit based on the detection value of the optical axis position detection unit and the detection value of the environmental condition detection unit, and controls the mirror driving unit based on the correction amount. Further, the storage means includes optical axis position data at the optical axis position detecting means which is changed in accordance with a change in environmental conditions, and light at the optical path end position of the laser light which is changed as the optical axis position is changed. The axis position data is stored.

[0006]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view of a laser plotter as a laser light device to which the present invention is applied. In this laser plotter, a pair of rails 2 is laid on the upper surface of a base 1, and a scanning table 3 is moved on the rails 2 by a drive motor 4 in the X direction in the figure. On the upper surface of the scanning table 3, a sheet material coated with a photosensitive material for pattern drawing, for example, a mask film 5 of a printed wiring board is placed.

A fixed table 6 is fixed on the base 1 so as to straddle the scanning table, and a laser optical system is provided on the fixed table 6. This laser optical system includes an Ar laser light source 7 that emits laser light, and a plurality of (here, three) mirrors 9, 10, and 11 that reflect the emitted laser light and finally guide the laser light to the scanning unit 8. And a half mirror 12 that transmits most of the laser light but reflects and branches a part of the laser light, an optical modulator 13 for on / off modulation of the laser light at the time of pattern drawing, and converges a laser light flux in the optical path. The scanning unit 8 includes a lens 14 and a laser beam that scans the surface of the mask film 5 on the scanning table 3 with the laser beam. The scanning unit 8 rotates at a high speed and reflects a laser beam.
lens, bending mirror 17, and condenser lens, and scans the mask film 5 on the scanning table 3 with the laser light in the Y direction as shown.

A position sensor 19 is disposed on the reflection surface side of the half mirror 12 so as to face the same, receives the laser beam reflected by the half mirror 12, and responds to a displacement amount with respect to a reference optical axis position. It is configured to output an optical axis position signal. The two mirrors preceding the half mirror 12, here mirrors 10 and 11, are each configured as a driving mirror, and the mirror 10 is vertically moved by a mirror driving mechanism (not shown in FIG. 1). The angle is adjusted, and the angle of the mirror 11 is adjusted in the left-right direction.

The position sensor 19, the half mirror 12, and the mirrors 10 and 11 constitute a part of an optical axis correction device. FIG. 2 is a block diagram of a main part of the optical axis correction device, and FIG. Is shown in FIG. The position sensor 1
Reference numeral 9 denotes, for example, a two-dimensional CCD or the like, and outputs a signal corresponding to the amount of deviation of the optical axis of the laser beam from the reference optical axis position in the vertical and horizontal directions. A signal processing circuit 20 is connected to the position sensor 19, and outputs a vertical optical axis position signal, a left and right optical axis position signal, and a light amount signal to a control unit 21 composed of a CPU based on the detected shift amount.

On the other hand, although not shown in FIG. 1, a temperature sensor 22 for detecting environmental conditions of the laser plotter, a humidity sensor 23,
An air pressure sensor 24 is provided. The detection signals from these sensors are processed in an environment signal processing circuit 25 and input to the control unit 21 as a temperature data signal, a humidity data signal, and an atmospheric pressure data signal.

Further, a memory 26 is connected to the control unit 21, and correction data of the optical axis position with respect to environmental conditions is stored in the memory 26 in advance. That is, the temperature change, humidity change,
How the optical axis position of the laser beam shifts at the position of the position sensor 19 and the optical axis position of the laser beam at the end position (laser beam drawing position: max film position) change while changing environmental conditions such as atmospheric pressure change. Is measured, and characteristics obtained from the measurement result are stored in the memory 26. The shift amount of the optical axis at the end position can be determined by, for example, installing another position sensor at the end position and measuring the shift amount of the optical axis position. Further, the environmental temperature, humidity, atmospheric pressure, and the like can be changed by, for example, installing a laser plotter in a laboratory or the like and conducting an experiment. still,
The above-mentioned change characteristics of the optical axis position require characteristics of the optical axis position shift amount in the vertical direction and the horizontal direction with reference to the optical axis detection position. Required for each environmental condition.

FIG. 4 shows an example of this, in which the temperature change with respect to the elapsed time when the laser plotter is driven, the change in the optical axis position in the position sensor at that time, and the change in the optical axis position at the end position at that time. It is a characteristic. Here, the optical axis position shift amount in the vertical direction is shown, but the same applies to the optical axis position shift in the horizontal direction. Although the change in humidity and the change in atmospheric pressure are not shown, there is also a change in the optical axis position with respect to the elapsed time in each case. The memory 26 receives information on environmental conditions from the control unit 21. Based on the information on the input environmental conditions, data on the amount of deviation of the optical axis position in the vertical direction based on the characteristics shown in FIG. The data is read from the memory 26 to the control unit 21.

On the other hand, a mirror drive circuit 27 is connected to the control section 21. The mirror drive circuit 27 connects the drive mirror 10 to the gear mechanism 3 as shown in FIG.
2 can control a motor driver 28 that drives a drive motor 30 that changes the angle in the vertical direction, and a motor driver 29 that drives a drive motor 31 that changes the angle of the drive mirror 11 in the left and right direction by the gear mechanism 33. .

In the laser plotter thus configured, when environmental conditions such as temperature, humidity, and atmospheric pressure change, the laser plotter has characteristics as shown in FIG. The optical axis position will be changed. Then, a change in the position of the optical axis in the middle of the optical path is detected by the position sensor 19, and this is input to the control unit 21. On the other hand, data signals from the temperature sensor 22, the humidity sensor 23, and the atmospheric pressure sensor 24 are input to the control unit 21, and information on environmental conditions based on these data signals is input to the memory 26 and stored in FIG. The optical axis position data at the optical axis detection position under the environmental condition and the optical axis position data at the end position at that time are read from the optical axis position shift amount characteristic as described above.

First, the optical axis position data at the optical axis detection position is compared with the optical axis position actually detected by the position sensor 19, and from this, the amount of deviation of the optical axis position at the optical axis detection position is detected. The correction amount δ is obtained. Further, from the optical axis position data of the optical axis detection position under the environmental conditions at this time and the optical axis position data of the terminal position, the optical axis shift amount of the terminal position with respect to the optical axis detection position is obtained, and the correction amount δ 'is obtained therefrom. . Then, the correction amount δ and the correction amount δ ′
Is added to the final correction amount, and the optical axis at the optical axis detection position is corrected based on the final correction amount. In this case, the control unit 21 drives the drive motors 30 and 31 by the motor drivers 28 and 29, and adjusts the angle of the drive mirror 10 in the vertical direction or the angle of the drive mirror 11 in the horizontal direction by each motor. . In this case, it is a matter of course that a detector for detecting the angular position of each of the drive mirrors 10 and 11 is provided, and the angle of each mirror is adjusted by feedback control.

Thus, at the end position, the optical axis adjustment is performed in consideration of the optical axis position deviation at the optical axis detection position and the optical axis position deviation amount at the scanning unit 8, and the scanning is performed due to a change in environmental conditions. Even if the optical axis misalignment occurs in the part,
Correction to offset this is performed, and it is possible to perform high-accuracy pattern drawing as designed on the mask film. The optical axis detection position is not limited to the position in the above-described embodiment, but may be provided at an arbitrary position in the optical path of the laser light.

[0017]

As described above, according to the present invention, the shift amount of the optical axis position caused by the change of the environmental condition is stored in the memory in advance, and the shift amount of the optical axis position according to the detected environmental condition is read out. Therefore, since the shift amount of the optical axis position in the middle of the optical path of the laser light is corrected based on the shift amount, even if the optical axis position at the end position of the laser light cannot be detected, the change in the environmental condition is caused. The optical axis position of the laser beam at the end position can be adjusted with high accuracy. When the present invention is applied to, for example, a laser plotter, laser beam scanning by a scanning unit can be performed as designed, and there is an effect that required pattern drawing can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a laser plotter to which an optical axis correction device according to the present invention is applied.

FIG. 2 is a schematic configuration diagram of a main part of the optical axis correction device of the present invention.

FIG. 3 is a system diagram of the optical axis correction device of the present invention.

FIG. 4 is a characteristic diagram showing a relationship between an optical axis detection position corresponding to a change in environmental conditions and an optical axis position shift amount at a terminal position.

[Explanation of symbols]

 Reference Signs List 3 scanning table 5 mask film 7 laser light source 8 scanning unit 9, 10, 11 mirror 12 half mirror 19 position sensor 21 control unit 22 temperature sensor 23 humidity sensor 24 atmospheric pressure sensor 26 memory 27 mirror drive circuit 30, 31 motor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-142307 (JP, A) JP-A-1-167719 (JP, A) JP-A-2-271315 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G02B 26/10

Claims (2)

(57) [Claims] 1. A drive mirror arranged in an optical path of laser light emitted from a laser light source and changing an optical path of the laser light when driven, a mirror drive unit for controlling the drive mirror, Means for detecting the optical axis position in the middle of the optical path, means for detecting environmental conditions such as ambient temperature, humidity, and atmospheric pressure of the laser light device, and means for storing an optical axis correction amount corresponding to a change in environmental conditions, A control unit that reads a corresponding optical axis correction amount from the storage unit based on the detection value of the optical axis position detection unit and the detection value of the environmental condition detection unit, and controls the mirror driving unit based on the correction amount; Optical axis correction device for laser light characterized by comprising: 2. The storage means stores optical axis position data at the optical axis position detecting means which is changed according to a change in environmental conditions, and an optical path end of the laser light which is changed according to the change of the optical axis position. 2. The optical axis correction device for laser light according to claim 1, wherein the optical axis position data at the position is stored.