JP2000055623A - Error correcting device for optical instrument for measurement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a measuring error generated in the case where objective lenses having different magnifications are used by changing-over. SOLUTION: In this error correcting device, a light source 14 and a position sensor 17 for detecting an incident position of a beam from the light source 14 are provided between an objective lens 16 (5) and an optical instrument body 1 to constitute a means for detecting a position of the objective lens 16 (5) with respect to the optical instrument body 1, a shifting amount of an optical axis at the switching time of the lens 16 (5) is detected by the means, and the shifting amount is stored to correct an observed value at the time of measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a measuring optical instrument, and more particularly, to a correction device for eliminating a measurement error caused when switching between objective lenses having different magnifications.

[0002]

2. Description of the Related Art For example, measuring optical instruments such as a measuring microscope and a non-contact three-dimensional measuring machine are used for measuring dimensions of printed circuit boards, processed parts, castings and the like. On the other hand, it is known that a measuring optical instrument is provided with a plurality of objective lenses having different magnifications and these are switched by using a revolver. In this case, taking a microscope as an example, when measuring a sample with a microscope, first capture the sample widely with a low-magnification objective lens to search for measurement points, and then switch to a high-magnification objective lens to enlarge it and measure accurately. Is used.

[0003] On the other hand, when measuring the dimensions of different sizes in one sample, the above method is applied to
It is useful to measure large and small measurement points by exchanging a plurality of objective lenses having different magnifications. However, since the objective lens is switched by mechanical means such as a revolver,
It is virtually impossible to reduce the optical axis shift to zero when switching lenses due to processing accuracy problems. There was an error.

Therefore, when measuring with high precision, conventionally, measurement is performed using only a high-magnification objective lens, or measurement is performed using an optical system having a variable magnification function in the middle while fixing the objective lens. Was.

[0005]

However, the former method has a problem that it is difficult to find a measurement point. Although the latter means does not cause a measurement error, there is a problem that the total magnification is limited to × 5 to × 10 due to the structure of the optical system, and the measurement magnification cannot be increased.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an error correcting apparatus which solves the above-mentioned problems of the prior art. In the optical device, by providing a means for detecting the position of the objective lens with respect to the optical device main body, the shift amount of the optical axis when the objective lens is switched is detected, and this shift amount is stored to correct the actual measurement value at the time of measurement. It is characterized by doing.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIGS. 1 and 2 show an example in which the error correction device of the present invention is applied to a measuring microscope. In the figure, reference numeral 1 denotes a main body of a microscope, which is provided with a moving table 6 which can move in three directions of XYZ, the moving table includes a Z table 7 which moves up and down in a Z (up and down) direction, and a Z table. XY tables 8A and 8B which are mounted on the XY table and move in the XY (plane) direction.
Reference numerals 9 and 10 in the figure denote coarse and fine dials for moving the Z table 7 up and down for focus adjustment.

In the measuring operation, first, the moving table 6
Place the sample on the top of the table, move the XY tables 8A and 8B to determine the measurement point, then move the Z table up and down to focus, and fine-tune the XY tables 8A and 8B to set the measurement start point . Then, by moving and setting the XY tables 8A and 8B to the measurement end point, the movement distance between the start point and the end point is calculated by a scale linked to the XY table.

In the figure, reference numeral 4 denotes a revolver, which is an objective lens barrel 5 having a built-in objective lens 13 (in the specification of the present application, the term "objective lens" includes both of them). Are provided according to the magnification.
The objective lens is sequentially positioned on the optical axis of the microscope by rotating and driving the revolver 4, and an objective lens having a desired magnification is selected and observed.

In FIG. 1, reference numeral 2 denotes an eyepiece tube, and reference numeral 3 denotes a television lens tube, and includes an eyepiece lens 11 and a CCD 12, respectively. In the TV lens barrel 3, the image is converted into an electric signal by the CCD 12 disposed on the imaging surface of the objective lens,
The image is displayed again on a monitor (not shown) after the image processing step. The movement of the moving table 6 for locating the measurement point is performed while observing the eyepiece tube 2 or the monitor. The moving table 6 includes a manual type and an electric type.
In the case of an electric type, the position is confirmed using a monitor.

In the above-mentioned microscope, means for detecting the position of the objective lens with respect to the microscope main body is provided. In this embodiment, a light source 14 is provided in each objective lens barrel 5 of the revolver 4 and the microscope main body 1 is provided. This means is provided by providing a position sensor 17 for detecting the incident position of the light beam from the light source of the objective lens located on the optical axis of the microscope. In this embodiment, a light emitting element such as an LED or a semiconductor laser is
7, a light position detecting element such as a PD or PSD is assumed, and the position of the light imaged on the position sensor 17 by the imaging lens 15 in the control circuit (not shown) and the reference position already adjusted and managed. Are compared to detect the shift amount of the optical axis of the objective lens, and this is stored. In this case, the light source 14 and the imaging lens 15 are accommodated in a lens barrel 16, but the lens barrel 16 may be provided integrally with the objective lens barrel 5.

The operation of the error correction device according to the present invention will be described below with reference to the flowchart of FIG. Here, a procedure for measuring the measurement start point with the objective lens adjusted to the reference position, and then exchanging the objective lens with one having a different magnification to measure the measurement end point will be described.

(Procedure S1) First, the power is turned on and the illumination lamp of the microscope is turned on.

(Procedure S2) While watching the image, turn the coarse / fine adjustment dial to focus the lens.

(Step S3) The sample is placed on the moving table and moved to the measurement start point.

(Step S4) The position of the measurement start point is determined by finely adjusting the XY of the moving table, and the coordinates of the start point (x
_0, y ₀ ) is measured and this value is stored.

(Step S5) The revolver is rotated to position the objective lens having a desired magnification on the optical axis of the microscope.

(Step S6) By exchanging the objective lens in step S5, the light source for detecting the position of the objective lens newly located on the optical axis of the microscope is turned on, and the position sensor receiving the light turns on the address of the incident position. Is detected.

(Step S7) The deviation detected from the address detected in step S6 and the origin (reference position) is calculated.
This is referred to as an error amount (△ x, △ y).

(Step S8) The error amount determined in step S7 is stored in the correction memory, and at this point the previous memory is erased.

(Step S9) The calibration is completed.

[0022] (Step S10) to move the sample to the measurement point of the next allowed to proceed measurement operation, performs positioning of the measurement end point by the XY fine adjustment of the moving table focused, end point coordinates (x _1, y ₁₎ Is measured and this value is stored.

(Procedure S11) Measured data (| x ₁ -x ₀
│, │y ₁ −y ₀ │) minus the error amount (△ x, △ y) to obtain a true value (│x ₁ -x _0- △ x│, | y ₁ -y _0-
Δy |) (see FIG. 4).

[0024]

According to the error correcting apparatus of the present invention having the above-mentioned structure, the calibration of the position is performed each time the objective lens is replaced. The objective lens can be replaced any number of times.

Accordingly, the optimum magnification can be selected according to the size of the measurement point, and the work of locating the measurement point can be performed with high accuracy, so that more accurate measurement of an object including a minute body can be performed. To play.

[Brief description of the drawings]

FIG. 1 is a side view of a measuring microscope in which an error correction device according to the present invention is implemented.

FIG. 2 is a cutaway side view showing the optical system according to the first embodiment;

FIG. 3 is a flowchart showing the operation of the error correction device according to the present invention.

FIG. 4 is a principle view showing the operation of the error correction device of the present invention.

[Explanation of symbols]

 Reference Signs List 1 Main body of measuring instrument 4 Revolver 5 Objective lens barrel 13 Objective lens 14 Light source 17 Position sensor

Claims (3)

[Claims] 1. A measuring optical device which uses an objective lens having a different magnification by switching, by providing means for detecting a position of the objective lens with respect to the optical device main body.
An error correction device for an optical device for measurement, which detects a shift amount of an optical axis when an objective lens is switched, stores the shift amount, and corrects an actual measurement value at the time of measurement. 2. An optical device for measurement in which an objective lens having a different magnification is used by switching, by providing a light source between the objective lens and the main body of the optical device and a position sensor for detecting an incident position of a light beam from the light source. A means for detecting the position of the objective lens with respect to the device body, detecting a shift amount of the optical axis when the objective lens is switched, storing the shift amount, and correcting an actual measurement value at the time of measurement. Error correction device for measuring optical equipment. 3. The error correction device for an optical instrument for measurement according to claim 2, wherein the lens barrel containing the light source and the coupling lens is integrated with the objective lens barrel.