JP2640113B2 - Micro rotary stage - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a micro rotary stage for performing micro rotary positioning in fields such as optical communication, optical analysis, VLSI manufacturing, and microscope measurement. .

[Conventional technology]

In the field of optical communication and optical analysis, when a minute rotation of a diffraction grating is performed, a minute rotation stage as shown in FIG. 3 is used.

The micro-rotating stage has a floating body 22 connected to a base 20 via a rotating shaft 21, and a gear formed at an end of the floating body 22.
22a and the ohm gear 23 were arranged in combination. When the ohmic gear 23 is rotated, the floating body 22 slightly rotates around the rotation shaft 21 in accordance with the gear ratio of each other, so that the sample stage (not shown) coupled to the floating body 22 slightly rotates. Had become.

[Problems of the prior art]

However, the conventional micro-rotation stage as described above is provided between the rotation shaft 21 and the idler 22, and between the gear 22a and the ohmic gear 23.
There were two sliding parts between the two, and due to the occurrence of backlash, abrasion during long-term use, or dimensional change due to temperature change, the accuracy could not be improved.

Further, since a small gap is required in the sliding portion, a minute rotation of the floating body 22 cannot be positioned.

For example, as a micro rotary stage, gear ratio 360: 1,
Consider an idler 22 having a turning radius of 57.3 mm. Floating body
In order for the 22 to rotate, a gap of about 3 μm is required between the rotating shaft 21 and the floating body 22, and between the gear 22a and the ohmic gear 23, respectively. Therefore, it is considered that there is an uncertain element of about 6 μm in accordance with the outer peripheral portion of the floating body 22,
The uncertain angle (β) at the time of the operation of 22 is expressed as follows using the turning radius (L) of the idler 22 and the uncertainty element (d) on the outer circumference of the idler.

β = tan ⁻¹ (d / L) (Formula I) = tan ⁻¹ (6/57300) ≒ 21.6 seconds As described above, the uncertain angle (β) of the floating body 22 is 21.6 seconds. This is required to be about one second. Therefore, in order to set the uncertain angle (β) to 1 second from the above (formula I), L = d / tan β = 6 / tan (1/3600) ≒ 1237 mm, and the radius of rotation of the floating body 22 is 1 m. Such a large one is not only practically unreasonable, but also has a large influence of thermal expansion and becomes a new uncertain factor.

As described above, in the conventional minute rotating stage, minute rotating positioning of about several seconds was impossible due to a structural problem.

[Means for solving the problem]

In view of the above, according to the present invention, a floating body is integrally formed through a thin portion inside a frame-shaped base, and a plurality of actuators are attached to an end of the floating body opposite to the thin portion. The other end of the foot member having one end attached to the tip of each actuator is brought into contact with a slip plate formed inside the base, and the actuator is attached between the foot members to constitute a micro rotary stage. is there.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The micro rotary stage shown in FIGS. 1 (a) and 1 (b) has a floating body 3 integrally formed with a thin portion 2 inside a frame-shaped base 1 so that the thin portion 2 is slightly bent. Accordingly, the floating body 3 can be slightly rotated around the rotation center O.

The thin portion 2 may be thinner than the other portions so as to be easily bent, and is not limited to the shape shown in FIG. For example, if the thin portion 2 is formed in a cylindrical shape, the rotation center O does not move and a minute rotation with high precision can be performed.

An actuator 4, a foot member 5, an actuator 6, and a foot member 7 are joined to the end of the floating body 3 opposite to the thin portion 2 in a direction radially extending from the rotation center O. An actuator 8 is also joined between the members 5 and 7, and a strain gauge 9 is attached to the actuator 8. A circumferential slip plate 10 centered on O is formed inside the base 1, and the foot member 5,
7 is in contact with the slip plate 10.

Further, a thin portion 11 for gap adjustment and a adjusting screw 12 are provided near the thin portion 2 of the base 1.
12, the gap between the foot members 5, 7 and the slip plate 10 during manufacturing can be corrected. A sample table 15 is connected to the floating body 3 by a bolt 13 so that an object is placed on the sample table 14.

This micro rotary stage has three actuators 4,
6 and 8 rotate the floating body 3 by an inching ohm operation which repeatedly expands and contracts with each other. The detailed operation is as follows.

As shown in the time chart of FIG. 2, in the case of clockwise rotation, the actuator 4 first contracts and the foot member 5
Is lifted from the slip plate 10 and subsequently the actuator 8 contracts, whereby the foot member 5 moves downward in the drawing. Here, the actuator is extended, and the foot member 5 is lowered onto the slip plate 10. Next, when the actuator 6 is contracted, the foot member 7 is lifted from the slip plate 10, and then the actuator 8 is extended to move the foot member 7 downward in the drawing. Here, the actuator 6 is extended and the foot member 7 is lowered onto the slip plate 10, and one cycle is completed. At this time, the foot members 5 and 7 have moved downward by the amount of expansion and contraction of the actuator 8, and the floating body has slightly rotated clockwise about O as the rotation center. The counterclockwise rotation can be performed by reversing the above operation.

Therefore, the rotation angle can be freely adjusted by setting the amount of expansion and contraction of the actuator 8 and the number of cycles so that the floating body 3 has the required rotation angle.

Further, since the micro rotary stage according to the embodiment of the present invention does not have a sliding portion during operation, it is possible to perform fine rotary positioning, and the accuracy deterioration due to aging and temperature change is reduced.

Furthermore, in the above-described embodiment, the two members 5 and 7 are shown. However, it is also possible to provide three or more members with the same structure and mount an actuator between the two members. is there.

Next, prototypes of the micro rotary stage shown in FIGS. 1A and 1B were prototyped, and various performance tests were performed.

The overall size is 20 mm in length, 40 mm in width, and 10 mm in thickness. The base 1, the floating body 3, the foot members 5 and 7 are all made of zirconia ceramic, and the foot members 5 and 7 and the slip plate 10 are formed.
Are mirror surfaces with each other of 0.8 s or less. Each of the actuators 4, 6, and 8 used a piezoelectric actuator formed by laminating a plurality of piezoelectric ceramics. The piezoelectric actuator is capable of performing minute expansion and contraction by adjusting the applied voltage. In practice, the maximum displacement is 5 μm.
Was used. The method of joining the actuators 4, 6, 8 with the floating body 3, and the foot members 5, 7 is such that a metal layer is formed in advance on a joint surface of each other by metallizing or the like, and the metal layers are fused together. It is.

Although the piezoelectric actuator itself has a large hysteresis and low accuracy, the strain gauge 9 is attached to the actuator 8 to measure the displacement, and since the control system feeds the displacement back to the actuator 8, the amount of expansion and contraction is high. can do.

As described below, the performance of such a micro rotary stage was excellent because it could be positioned for about several seconds.

Maximum variable angle 1.2 degrees 1 step angle 1 to 43 seconds variable 1 step accuracy ± 0.68 seconds 1 step stability ± 1 second / year or less Also, various materials such as ceramic and metal are used for the base 1 and other materials. However, as shown in Table 1, ceramics such as alumina and zirconia have a small coefficient of linear expansion and a large Young's modulus as compared with metals, so that they have excellent resilience to bending.
It is better to use a ceramic material. Among them, zirconia showed the strongest and most excellent results.

[Effects of the Invention] As described above, according to the present invention, a floating body is integrally formed via a thin portion inside a frame-shaped base, and an end of the floating body opposite to the thin portion. A plurality of actuators are attached, the other end of the foot member having one end attached to the tip of each actuator is brought into contact with a slip plate formed inside the base, and the actuator is attached between the foot members. Because of the micro-rotation stage, there is no sliding part, so not only micro rotation positioning is possible, but also high-performance micro with features such as small deterioration of accuracy due to aging and temperature changes. A rotary stage can be provided.

[Brief description of the drawings]

FIG. 1A is a side view showing a micro rotary stage according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along the line AA in FIG. FIG. 2 is a time chart for explaining the operation of the micro rotary stage according to the embodiment of the present invention. FIG. 3 is a sectional view showing a conventional minute rotary stage. 1: Base, 2: Thin section 3: Floating body, 4, 6, 8: Actuator 5, 7: Foot member, 9: Strain gauge 10: Slip plate

Claims (1)

(57) [Claims] A floating body is integrally formed inside a frame-shaped base through a thin portion, and a plurality of floating members are provided at ends opposite to the thin portion in a direction radially extending from the thin portion. , The tip of the foot member is brought into contact with a slip plate formed in a circumferential portion around the thin portion inside the base, and the actuator is mounted between the foot members. A very small rotating stage.