JP2002350711A - Method and device for adjusting positioning shift - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for adjusting positioning shift capable of positioning surface by adjusting two axes, in the shift adjustment of an optical element having the planes whose relative angles are drastically different from each other and to provide the positioning shift adjusting device. SOLUTION: In the positioning shift adjusting method, an X axis which is orthogonal to an axis θ and at an optional angle to a target axis is assumed on a rotary θ-axis stage and the rotation around the X axis is expressed by an axis α, the positional adjustment of the plane is performed with reference to the rotary θ-axis stage and the α-axis stage, then, the optional plane is made vertical to the target axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for adjusting a tilt of a positioning device, and more particularly, to a polygon mirror, a prism, a prism mounted on a laser printer, a digital copier or the like and having a plurality of planes having different relative angles. The present invention relates to a device for adjusting the tilt of a positioning device when manufacturing, measuring, or inspecting an optical element such as an array.

[0002]

2. Description of the Related Art Conventionally, when it is desired to position a plane in the optical element, for example, to arrange the plane perpendicular to the optical axis, it is necessary to finely adjust the tilt of the plane. This tilt adjustment can be performed using two orthogonal axes, for example, if the rotation axes around the X axis and the Y axis are the α axis and the β axis, respectively, in one plane, the α axis and the β axis. When there are a plurality of planes having greatly different relative angles, for example, in the prism 51 shown in FIG. 5A or the prism array 52 shown in FIG. 5B, in order to align an arbitrary plane in the optical axis direction, Assuming that the rotation axis around the Z axis is the θ axis, three axes of α axis, β axis, and θ axis are required. In general, when a large tilt adjustment is required, a rotary shaft is provided to rotate around the axis, or a tilt is adjusted by a stage called a swivel or a gonio.

[0003] FIG. 6 is a view showing a 3rd stage using a swivel stage.
It is the schematic which shows the structure of a shaft tilt adjustment apparatus. (A) of the same figure is a plan view, (b) of the same figure is a front view, (c) of the same figure
Is a right side view. As shown in FIG. 3B, a swivel stage 62, 63 corresponding to an α-axis and a β-axis is combined on a rotary stage 61 corresponding to the θ-axis so as to be orthogonal, and a prism 64 is mounted thereon. I do. With this configuration, it is possible to position the two planes of the prism 64 so as to be perpendicular to an arbitrary axis, for example, the optical axis 65 of the laser as shown in FIG.

If the amount of tilt adjustment is small, a so-called three-point adjustment is performed by supporting the plane at three points and making two of them movable and the other one rotatable. Supporting methods are also used.

[0005]

However, when a stage such as a swivel is combined, at least a three-axis stage is assembled, which lowers the resonance point and tends to cause minute vibration. Was. In many cases, the work mounting surface is installed at a considerably higher place than the installation base surface, and errors in the lower stage system are enlarged, so-called Abbe errors. Need attention. In the case of three-point support, three points are not necessarily constrained, and when the θ-axis rotation is performed after the tilt adjustment, a lateral load may be applied to cause a positional shift. Also,
Mechanically it was difficult to increase rigidity, it was vulnerable to vibration, and it was disadvantageous for supporting large loads. Further, in recent precision positioning, for example, positioning on the order of submicrons, it cannot be ignored as an error factor. That is, if there are a plurality of planes having different relative angles,
Since the shaft is required and the height is higher than the installation base surface, the error is enlarged, which is disadvantageous in ultra-precision positioning. Also, 3
Although the point support can be reduced in height, vibration is likely to occur and the load bearing capacity is small. In addition, it is weak against a lateral load due to the rotation of the θ-axis, so that the θ-axis cannot be moved after the adjustment.

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and in position adjustment of an optical element having a plurality of planes having greatly different relative angles, positioning can be performed on two or more planes by adjusting two axes. An object of the present invention is to provide a tilt adjustment method and a device thereof.

[0007]

In order to solve the above-mentioned problems, according to a positioning and tilt adjusting method of the present invention for positioning an optical element having a plurality of planes having different relative angles, a rotary θ-axis stage is provided. In addition, assuming the X axis orthogonal to the θ axis and having an arbitrary angle with respect to the target axis, and the rotation around the X axis is the α axis, the position adjustment of the plane is performed by the rotating θ axis stage and the α axis stage. Then, an arbitrary plane is aligned perpendicular to the target axis. Therefore, when positioning a plurality of planes having different relative angles, it is possible to adjust even two axes.

In another aspect of the present invention, there is provided a positioning and tilt adjusting device comprising: a rotary θ-axis stage; a rotary α-axis stage around an X-axis orthogonal to the θ-axis and having an arbitrary angle with respect to a target axis; It is characterized by having a drive source for rotating the θ-axis stage and the rotation α-axis stage, a control mechanism for the drive source, and a positioning resolution improving mechanism. Therefore, when positioning a plurality of planes having different relative angles, it is possible to provide a positioning tilt adjustment device that can be adjusted even with two axes.

Further, the arbitrary angle is 45 degrees with respect to the target axis.
Since the angle is 135 ° or 135 °, it is possible to calculate the feed amount of the forward / reverse rotation as substantially the same, so that the control parameters can be simplified in the positioning of a substantially angled work such as a right-angle prism.

Also, since the origin sensor for detecting the origin of the axis is attached to the θ axis and / or α axis, calibration can be performed by this origin sensor and the angle can be adjusted to an arbitrary angle immediately after the work is set. .

Further, since the origin sensor is an eddy current sensor, it is possible to detect the origin with high accuracy at relatively low cost.

Further, since a stepping motor is used as the driving source, the stepping motor has less servo vibration than the servomotor. Even after the tilt adjustment, the position accuracy can be maintained with low vibration.

Further, by providing the drive source with a brake mechanism, the vibration of the motor can be attenuated by forcibly contacting the air pad with the rotor, and the brake can be prevented from dropping off during a power failure.

Further, by providing the drive source with a damper, vibration during rotation of the motor can be suppressed, and positioning accuracy can be improved.

Further, since the control mechanism uses the motor driver of the PWM control, the current at the time of the motor control can be reduced, and the drive system can be configured to save power.

Further, since the control mechanism uses a motor driver using a linear amplifier, it is possible to suppress minute vibrations generated during both the movement of the motor and the standstill of the PWM control.

Further, since the positioning resolution improving mechanism electrically divides the positioning control pulse, the positioning resolution of the tilt adjustment is improved relatively inexpensively by the electric dividing method.

Also, the positioning resolution improving mechanism uses a harmonic gear deceleration mechanism, so that it has low vibration and no backlash, and improves the resolution of adjustment, as compared with an electric dividing method having a surface with weak stability. I do.

Further, the coupling between the drive source and the rotary shaft is fixed by a coupling, so that the rigidity is improved.
The resilience is reduced, it is strong against vibrations, and it can reliably transmit even minute rotation.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The positioning tilt adjustment method of the present invention is based on the assumption that an X-axis that is orthogonal to the θ-axis and has an arbitrary angle with respect to a target axis is provided on a rotating θ-axis stage. When the rotation is the α-axis, the position of the plane is adjusted by the rotating θ-axis stage and the α-axis stage, and an arbitrary plane is aligned perpendicular to the target axis.

[0021]

FIG. 1 is a schematic diagram showing the configuration of a positioning and tilt adjusting device according to a first embodiment of the present invention. (A) of the same figure is a plan view, (b) of the same figure is a front view, (c) of the same figure
Is a right side view. In (b) of the figure, a swivel stage 12 of a rotating α-axis around the X-axis is installed on a rotating stage 11 of the θ-axis installed on a vibration isolation table (not shown), and a plurality of swivel stages having different relative angles are provided. An optical element having a flat surface, for example, a prism array 13 was disposed thereon. The θ axis is set perpendicular to the vibration isolation table plane, supplies energy from an energy source (not shown) to a drive source (not shown) through a control mechanism (not shown), and provides a positioning resolution (not shown). It can be positioned at any angle by the enhancement mechanism. The rotating stage 11 is selected so that positioning accuracy does not decrease even when a large load is loaded. On the rotary stage 11, a θ parallel to the base surface of the vibration isolation table
Assuming that the axis crossing the axis is the X axis, and defining the rotation axis around the X axis as the α axis, the swivel stage 12 is arranged to correspond to the α axis. The prism array 13 is arranged on the swivel stage 12, and at this time, the array direction is arranged so as to coincide with the α-axis. Prism array 1
Reference numeral 3 denotes a plurality of surfaces having different relative angles, for example, in a right-angle prism array, a plane has a plane having a relative angle of 90 °.
The axis perpendicular to this plane and the α axis are at any angle, for example, 45 °
In this case, the plane can be arranged perpendicular to the optical axis 14. Actually, since each prism has an angle error at the time of manufacture, fine adjustment is required when trying to exactly match the optical axis. Conventionally, the tilt adjustment around the X axis and the Y axis called the α axis and the β axis as shown in FIG. 6 has been performed. In the present embodiment, the θ axis is added for the tilt adjustment of a plurality of surfaces having different relative angles. Therefore, it is possible to adjust the tilt of one of the α axis and the β axis and the θ axis. Thus, by moving the θ-axis or α-axis, it is possible to adjust the tilt even if there is no β-axis in the mechanism.

Next, the structure of a positioning and tilt adjusting device according to a second embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 2, the θ-axis rotation stage 21 is installed on a vibration isolation table (not shown) such that the rotation axis is parallel to the perpendicular to the installation surface. On this rotating stage 21, θ
If an axis that intersects the axis at 90 ° is the X axis, and the rotation around the X axis is defined as the α axis, the axis of the rotary stage 22 is set so as to coincide with the α axis. A work 23, for example, a prism array having a plurality of planes having different relative angles is set on the rotary stage 22, and each surface of the prism array is aligned with the optical axis. Such a rotary stage 22 is disadvantageous in terms of height as compared with the three-point support method, but has a high rigidity, so that a mechanism resistant to minute vibrations can be obtained.

Here, the entire movement will be described first with reference to FIGS. FIG. 3 shows a case where the plane portion of the work side surface 24 of the work side surface 24 and the work side surface 25 of the work 23 coincides with the optical axis 27 of the laser interferometer 26. When measuring the plane accuracy of the plane with the laser interferometer 26, the measurement is performed by returning and interfering the reference light and the light irradiated on the target surface, but each prism portion of the work 23 includes a minute angular error. Have been. It is sufficient that this angle error does not cause a problem during measurement. However, since measurement cannot be performed without returning light, adjustment of the tilt is required.
In this case, since the α axis is not parallel to the perpendicular of the measurement plane, θ
The tilt can be adjusted with the two axes, the axis and the α axis.

FIG. 4 shows that the rotary stage 21 is rotated from FIG. 3, and the plane portion of the work side surface 25 of the work side surface 24 and the work side surface 25 of the work 23 coincides with the optical axis 27 of the laser interferometer 26. Is the case. As before, the α-axis is the measurement plane, and in this case, the perpendicular to the work side surface 25 is not parallel to the α-axis, so that the two axes of the θ-axis and the α-axis can be adjusted.

Even if such a configuration is not adopted, position adjustment is relatively easy if there are three axes of the θ-axis, α-axis and β-axis as in the conventional case, but it is most difficult to overlap the stage systems. This causes an increase in error factors with respect to the workpiece 23 on the upper side, and lowers measurement accuracy. In the case of a long object such as a prism array, the combination of the α-axis and the β-axis causes poor balance and tends to cause a reduction in rigidity. When measurement accuracy on the order of submicrons is required, an increase or decrease in one axis of the stage causes a large difference in positioning accuracy.

Next, low-vibration (high-rigidity) and high-precision tilt adjustment will be described with reference to FIG. 2. When discussing accuracy on the order of submicrons, a high-rigidity mechanism with a low center of gravity and vibration as much as possible are used. A mechanism that does not generate or that easily absorbs vibration is required. Since the rotary stages 21 and 22 have the origin sensor 28, the positioning accuracy is improved even at the time of initial start-up and recovery from abnormal operation. The origin sensor 28 uses an eddy current type proximity sensor instead of a photomicrosensor that is often used in the related art, thereby improving the edge detection accuracy of the origin by about one digit. Α-axis at 45 ° or 135 ° to optical axis
When the tilt angle is set at the above angle, the movement parameters of the two surfaces having different relative angles can be treated as substantially equal in the tilt adjustment of the right-angle prism array or the like, so that the control parameters can be simplified.

In order to reduce the drive of the rotary stages 21 and 22, the use of the stepping motor 29 suppresses the servo vibration at the time of stopping the power supply as much as possible. Furthermore, a contact type air brake 30 is attached to the rotation axis on the α-axis to attenuate minute vibrations generated from the motor and the control system. The air brake 30 also functions as an emergency safety device such as a power failure. A rotation damper 31 is provided at the end of the α-axis stepping motor shaft to reduce vibration during rotation of the motor. Further, the control driver of the stepping motor 29 is P
Drive energy is saved using WM control. However, since the PWM control oscillates at a high frequency, it sometimes becomes a vibration source for oscillating a peripheral mechanism or a coil inside the motor. Therefore, when a minute vibration caused by PWM becomes a problem, the linear amplifier is used. The use of a motor driver that uses the above prevents the occurrence of minute vibrations.

In addition, since the tilt adjustment often requires a small amount of movement, a general stepping motor 29 is required.
The step angle of 0.72 ° is often insufficient. Therefore, as a step angle dividing method, a method of improving the positioning resolution by electrically dissolving the control pulse is adopted. This method can increase the resolution at low cost, but generates vibration at low speed, is vulnerable to load fluctuation, and generates very small vibration even at rest. If these vibrations become a problem, the mechanical gear, especially the harmonic gear 32, should be used instead of improving the resolution electrically.
By using this, it is possible to configure a drive system that is less likely to vibrate even at low speeds, load fluctuations, and large inertia, thereby improving the positioning resolution.

Also, the coupling between the motor shaft and the rotary shaft is not performed by a disk coupling or a helical coupling, but is completely fixed by a rigid coupling 33, so that the rigidity is improved and the driving with a small pulse is ensured. To improve the positioning accuracy.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications and substitutions can be made within the scope of the claims.

[0031]

As described above, according to the positioning and tilt adjusting method of the present invention for positioning an optical element having a plurality of planes having different relative angles, the position is orthogonal to the θ axis on the rotating θ axis stage. Assuming the X axis having an arbitrary angle with respect to the target axis, and if the rotation around the X axis is the α axis, the position of the plane is adjusted with the rotating θ axis stage and the α axis stage, and To align any plane vertically.
Therefore, when positioning a plurality of planes having different relative angles, it is possible to adjust even two axes.

In another aspect of the present invention, there is provided a positioning tilt-adjusting device comprising: a rotating θ-axis stage; a rotating α-axis stage orthogonal to the θ-axis and having an arbitrary angle with respect to a target axis around an X-axis; It is characterized by having a drive source for rotating the θ-axis stage and the rotation α-axis stage, a control mechanism for the drive source, and a positioning resolution improving mechanism. Therefore, when positioning a plurality of planes having different relative angles, it is possible to provide a positioning tilt adjustment device that can be adjusted even with two axes.

Further, the arbitrary angle is 45 degrees with respect to the target axis.
Since the angle is 135 ° or 135 °, it is possible to calculate the feed amount of the forward / reverse rotation as substantially the same, so that the control parameters can be simplified in the positioning of a substantially angled work such as a right-angle prism.

Since the origin sensor for detecting the origin of the axis is attached to the θ axis and / or α axis, calibration can be performed by the origin sensor, and the angle can be adjusted to an arbitrary angle immediately after the work is set. .

Further, since the origin sensor is an eddy current sensor, it is possible to detect the origin with high accuracy at relatively low cost.

Further, since the stepping motor is used as the driving source, the stepping motor has less servo vibration than the servomotor. Even after the tilt adjustment, the position accuracy can be maintained with low vibration.

Further, by providing the drive source with a brake mechanism, the vibration of the motor can be attenuated by forcibly contacting the air pad with the rotor, and the brake can be prevented from dropping off during a power failure.

Further, by providing a damper in the drive source, vibration during rotation of the motor can be suppressed, and positioning accuracy can be improved.

Further, since the control mechanism uses the motor driver of the PWM control, the current at the time of the motor control can be reduced, and the drive system can be configured to save power.

Further, since the control mechanism uses a motor driver using a linear amplifier, it is possible to suppress minute vibrations generated during both the movement of the motor and the standstill of the PWM control.

Further, since the positioning resolution improving mechanism electrically divides the positioning control pulse, the positioning resolution of the tilt adjustment is improved relatively inexpensively by the electric dividing method.

Further, since the positioning resolution improving mechanism uses a speed reduction mechanism using a harmonic gear, the vibration resolution and the backlash-less operation are improved and the resolution of the adjustment is improved as compared with an electric dividing method having a weakness in stability. I do.

Further, since the coupling between the drive source and the rotary shaft is fixed by the coupling, the rigidity is improved,
The resilience is reduced, it is strong against vibrations, and it can reliably transmit even minute rotation.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a positioning and tilt adjusting device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a positioning and tilt adjusting device according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing a configuration of a positioning and tilt adjusting device according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram showing the configuration of a positioning and tilt adjusting device according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating an example of an optical element to be worked;

FIG. 6 is a schematic diagram showing a configuration of a three-axis tilt adjusting device using a swivel stage.

[Explanation of symbols]

11, 22, 22; rotary stage, 12; swivel stage, 13; prism array, 14, 27; optical axis, 2
3; Work, 24, 25; Work side, 26; Laser interferometer, 28; Origin sensor, 29; Stepping motor,
30; air brake; 31; rotary damper; 32; harmonic gear; 33;

Claims (13)

[Claims] 1. A positioning tilt adjustment method for positioning an optical element having a plurality of planes having different relative angles, comprising: a X-axis on a rotating θ-axis stage, which is orthogonal to the θ-axis and has an arbitrary angle with respect to a target axis. Axis, and rotation about the X axis is α
In the case of using an axis, a position of a plane is adjusted by the rotating θ-axis stage and the α-axis stage, and an arbitrary plane is vertically aligned with respect to the target axis. 2. A positioning tilt adjustment device for positioning an optical element having a plurality of planes having different relative angles, comprising: a rotating θ-axis stage; and an X-axis orthogonal to the θ-axis and having an arbitrary angle with respect to a target axis. Positioning tilt adjustment characterized by having a peripheral rotating α-axis stage, a driving source for rotating the rotating θ-axis stage and the rotating α-axis stage, a control mechanism for the driving source, and a positioning resolution improving mechanism. apparatus. 3. An apparatus according to claim 2, wherein said arbitrary angle is 45 ° or 135 ° with respect to said target axis. 4. The apparatus according to claim 2, wherein an origin sensor for detecting an origin of the axis is attached to the θ axis and / or the α axis. 5. An apparatus according to claim 4, wherein said origin sensor is an eddy current sensor. 6. The apparatus according to claim 2, wherein a stepping motor is used as the drive source. 7. The apparatus according to claim 2, wherein the drive source includes a brake mechanism. 8. The positioning tilt adjusting device according to claim 2, wherein a damper is provided in the driving source. 9. The apparatus according to claim 2, wherein said control mechanism uses a PWM-controlled motor driver. 10. The apparatus according to claim 2, wherein the control mechanism uses a motor driver using a linear amplifier. 11. The apparatus according to claim 2, wherein the positioning resolution improving mechanism electrically divides the positioning control pulse. 12. The apparatus according to claim 2, wherein said positioning resolution improving mechanism uses a speed reducing mechanism based on a harmonic gear. 13. A coupling part between the drive source and the rotation shaft,
3. The apparatus of claim 2, wherein the apparatus is fixed by a coupling.