JPS58120102A - Optical displacement gage capable of two-axes light servo with one detecting part - Google Patents

Abstract

PURPOSE:To make the device compact, light weight, and highly accurate, by adding a current for shifting the target by the diameter of an aperture to the correction data of the target at the time of the light servo, thereby shifting the target. CONSTITUTION:A time division switch 3 is normally switched at three kinds of timings based on the relationship between the outputs of a horizontal axis coil and a vertical axis coil and a quantity of light. At the time of the light servo for detecting the quantity of the light, a shift voltage +alpha corresponding to the aperture diameter is added to the horizontal axis output and the vertical axis output, and the target is deviated from the aperture. When the deflecting current, to which the shift voltage +alpha is added, is applied to the horizontal axis coil H and the vertical axis coil V, the target is completely deviated from the aperture. The quantity of the light at this time is received by a photomultiplier. Said signal is appropriately processed, a high voltage circuit 16 is controlled, and the high voltage is varied by the increment of the variation in the quantity of the light. As a result, the fluctuation of the output data is prevented regardless of the quantity of the incident light.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical displacement meter capable of two-axis write servo with one detection section.

The conventionally well-known optical two-axis displacement meter uses two detection units, namely photo multipliers, to detect displacement in the vertical and horizontal directions, respectively, to adjust the light intensity for each axis. In other words, two-axis write servo was performed. As a result, it is expensive because it requires two photo circles with equal characteristics in principle, and it is inconvenient to handle because the camera has a dog-like shape and is heavy.

Furthermore, one incident image is divided by mirrors, and each image is divided into two parts.
...Since it is necessary to form an image at the center of the circle, precise adjustment of the optical system is required. Also, since it uses complex feedback control, the electrical circuit is complex and operation tends to be unstable. there were. The present invention eliminates the above-mentioned drawbacks of the prior art and allows two detectors to be used in one detector.
The purpose of the present invention is to provide an optical displacement meter capable of axial light servo.

The object of the invention is achieved by an optical displacement meter as defined in the claims.

Since the optical displacement meter according to the present invention can omit one photo mark, the camera has a small eaves size and is advantageous in terms of price. Furthermore, there are advantages in that optical and electrical adjustments and operations are facilitated.

Hereinafter, the present invention will be described in detail with reference to accompanying drawings showing examples.

The output of the photomultiplier 1 that receives the light is amplified by the preamplifier 2 and divided into three parts by the time division switch 3. The three divided outputs are applied to a horizontal (H) axis amplifier 4, a light servo (r, , S) amplifier 5, and a vertical (V) axis amplifier B, respectively.

The output of the horizontal axis amplifier 4 is a coil voltage detection amplifier 7 for horizontal axis output, and a coil shift voltage detection amplifier 8 for vertical axis output.
, and is applied to the light servo water half-axis coil shift voltage detection amplifier 9. The outputs of these amplifiers 7, 8.9 are applied to the horizontal axis coil 1 drive amplifier 10 which drives the horizontal axis coil H according to each timing.

The output of vertical axis amplifier B is applied to vertical axis output coil voltage detection amplifier 11, horizontal axis output coil soft voltage detection amplifier 12, and write servo vertical axis coil shift voltage detection amplifier 13. Each of these amplifiers 11.12
．． The output of 16 is sent to the vertical axis coil 9 according to each timing.
It is applied to the vertical axis coil drive amplifier 14 which drives the voltage V.

The output of the write servo amplifier 5 controls a high voltage circuit 16 for the photo full 1 via a matching amplifier 15. The output of the high voltage circuit 16 is supplied as a high voltage to the photomultiplex 1 to control the output (brightness) of the photomultiplex.

The drive output of the horizontal axis coil H is taken out as a measurement output from the horizontal axis output terminal Ho via the detection amplifier 17 and the data amplifier 18.

The drive output of the vertical axis coil (2) is taken out as a measurement output from the vertical axis output terminal Vo via the detection amplifier 19 and the data amplifier 20.

The optical displacement meter that is the object of the present invention originally forms a servo loop system. In other words, the electron beam is appropriately deflected by strong and weak incident light from bright and dark targets (not shown), and controlled so that the electron beam is always received at the center of the aperture in front of the photo full 1. The zero method method is adopted. At this time, the output supplied to the deflection coil, ie, the feedback correction current, indicates the amount of displacement of the target.

The device according to the present invention has the above-described configuration, and uses an appropriate switching circuit to time-divide the output of the photomultiplier 1 at appropriate timings. At this time, in order to detect the light servo output, that is, the amount of light, the target must be located at the center of the aperture. Therefore, in the apparatus according to the present invention, the target correction effect is utilized during write servo, and a current for shifting -s by the aperture diameter is added to this correction data to shift the target. In other words, whether the time division switch 3 is switched at the timing shown in the table below,
When using light servo to detect the amount of light, shift voltage + α corresponding to the aperture diameter is applied to the horizontal axis amplifier and vertical axis output.
is added and the target is removed from the aperture.

The deflection current added by the shift voltage + α is applied to the horizontal axis coil H.
By supplying the light to the vertical axis coil (1) and the vertical axis coil (2), the evening light is completely removed from the aperture, and the amount of light at this time is taken into the photo circle. This signal is processed appropriately to control the high voltage circuit 16, and the high voltage is changed by the amount of change in light amount. As a result, fluctuations in the output data are prevented despite changes in the measurement environment, especially changes in the amount of incident light from the Tarkerat, making it possible to perform highly accurate displacement measurements with few errors.

Although the present invention provides an optical displacement meter that is small, lightweight, and capable of measuring displacement with high accuracy, it will be obvious that many modifications and variations can be made within the scope of the present invention.

[Brief explanation of the drawing]

The attached figure is a circuit diagram of an optical displacement meter capable of two-axis write servo with one detection section according to the present invention. The correspondence of reference symbols in the figure is as follows. 1° Photo circle 2: Preamplifier 3: Time division switch 4: Horizontal axis amplifier 5 Nilight servo amplifier 6: Vertical axis amplifier 7, 8.9.10.1
7.18: Horizontal axis measurement circuit 11, 12.13.
14.19.20 Vertical axis measurement circuit 16: High voltage circuit
I (= horizontal axis coil V: vertical axis coil

Claims (1)

[Scope of Claims] A light servo circuit is provided to measure the displacement using a deflection current to correct the electron beam to a predetermined position due to strong and weak incident light from a bright and dark target, and to adjust changes in the amount of incident light during measurement. In a two-axis optical displacement meter, the electric signal corresponding to the incident light is time-divisionally divided into horizontal axis measurement circuits (4, 7, 8, 9, 10, 17, 18) and vertical axis measurement circuits (6, 11, 12). ,13,14,19,20
) and a light servo circuit (s, 1s) for controlling the high voltage circuit (16). An optical system capable of two-axis write servo with one detection unit, characterized by including a circuit (8, 9; 12, 13) for applying a required shift signal to the other-axis coil during a period other than the self-axis output timing. displacement meter.