JPH04290906A - Shape measuring device - Google Patents

Abstract

PURPOSE:To measure a surface having a wide spread larger than the aperture continuously, precisely, without a gap by moving a measuring head to an applicable divisions one by one under electrical control, and photographing the interference pattern with adjoining divisions overlapped partially. CONSTITUTION:By a supporting member 6 a stage 2 is pinched slidably upon a base board 1 which has undergone a mirror face processing, and an object to be measured 9 is put precisely in place on the surface of the stage 2. A measuring head 3 is secured to a slider 14 which can slide in the X-axis direction along a guide bar 7. A light source (preferably, He-Ne laser) and a measuring means (for example, electric charge coupling element) to photograph the interference pattern formed by laser beam are accommodated in this head 3, and the photographed interference pattern is recorded by a recording means. The head 3 is moved in the X-axis and Y-axis directions by No.1, No.2 moving means 10 and 11, respectively, so that it travels to the centers of different divisions of the measuring surface 9a one by one. A control means controls the light source and also controls operation of motors 12, 15 of the No.1, No.2 control means 10, 11.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape measuring device capable of measuring a relatively large surface to be measured, which is larger than the aperture of a lens system included in the optical measuring device.

0002

2. Description of the Related Art Interferometers, for example, are often used as means for measuring the flatness and curved shape of various parts, products, etc. (hereinafter referred to as objects to be measured) with high precision. When measuring the flatness of a flat object to be measured using this interferometer, a laser beam is irradiated and projected toward the measurement surface of the object, and the laser beam is reflected back by the object. The unevenness of the measurement surface can be measured with high accuracy from the pattern of interference fringes formed.

0003

[Problem to be solved by the invention] By the way,
The interferometer has a finite aperture of about 50 mm at most, and it has been impossible to continuously and accurately measure the entire measurement area wider than the aperture. Therefore, when attempting to measure a surface to be measured that has a larger expanse than the aperture of the interferometer, it is conceivable to move the object to be measured and perform the measurement work in multiple steps.

[0004] However, when this measurement work is repeated many times, when moving the observation area, there are two problems: (1) the surface to be measured may cause slight vibrations up and down, and (2) the measurement area may be ■ There is a risk of making a large error at the boundary between measurement areas. ■ There is a risk of missing measurements when repeating the measurement process many times, etc. This causes problems.

[0005] Furthermore, when performing this measurement repeatedly, for example, if a plate glass with a thickness of 1 cm is used as the measurement object, the coefficient of linear expansion of this glass is approximately 1 x 10-5.
[deg-1], so the temperature of the measurement surface is only 1
Even a change in temperature causes expansion and contraction of 1/10 μm. Under these circumstances, it is important to carry out the measurement work as efficiently and quickly as possible, and in particular, the body temperature of the worker may have a subtle influence, causing a non-negligible expansion change on the measurement surface.

Therefore, the present invention aims to solve the above-mentioned problems.In other words, even if the object to be measured has a wide area larger than the aperture of the interferometer, it is possible to Continuously and quickly over the entire surface without any gaps.
Another object of the present invention is to provide a shape measuring device that can perform highly accurate measurements.

[0007]

[Means for Solving the Problems] That is, the shape measuring device of the present invention includes a light source, a stage movably provided with an object to be measured placed on its upper surface, and a stage from which the object to be measured is placed from the light source. The measuring device is provided above the stage and is movable along the stage, and includes a measuring means for measuring stripes formed according to the thickness of the object to be measured using light irradiated onto the surface of the object to be measured. a head, a moving means for moving the measuring head along the surface to be measured of the object to be measured, and a moving means for moving the measuring head along the surface to be measured of the object to be measured; and control means for controlling the operation of the moving means.

[0008]

[Operation] The shape measuring device of the present invention operates the moving means appropriately and rapidly under electrical control of the control means to sequentially move the measurement head to a predetermined position in each divided region, and measures the object to be measured in each divided region. The photographing means photographs the interference fringes in each divided region such that the measurement region of the surface at least partially overlaps the measurement region of the adjacent divided region.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a shape measuring device according to the present invention, and this shape measuring device includes a base 1
, a stage 2, a measurement head 3, a moving means 4, and a control means 5 (see FIG. 2).

The base 1 is a flat plate mirror-finished so that both the upper and lower surfaces have highly accurate flatness, and in this embodiment, a vibration-absorbing rubber body (
(omitted) are fixed to the four corners. A pair of supports 6 are fixed to the upper surface (hereinafter referred to as the reference surface) 1a of the base 1, and a stage 2 is slidably held between the supports 6. It is installed. Note that a pair of guide bars 7 are installed on the upper side between the pair of supports 6.

[0011] The stage 2 has both upper and lower surfaces mirror-finished to have highly accurate flatness, and both sides are fitted with fitting protrusions 6a of the support 6 to serve as guides when the stage 2 moves. A groove 2a is carved therein. This stage 2 also includes a screw shaft 1 of a moving means 4, which will be explained later.
A screw hole 2b into which the screw 6 is screwed is cut in a direction parallel to the groove 2a. Note that the object to be measured 9 is accurately placed at a predetermined position on the upper surface of the stage 2 in order to measure the surface to be measured 9a.

The measuring head 3 is attached to a slider 14 that can freely slide between the supports 6 along a guide bar 7 in the left-right direction of the X-axis, and a light source 8 (see FIG.
), measurement means and other optical systems (both not shown)
is provided. The light source 8 is for irradiating/projecting a laser beam (reference beam) with a wavelength λ toward the surface to be measured 9a, and in this embodiment, helium neon (He −
Ne ) laser is used. The measuring means is for photographing interference fringes formed according to the surface condition of the surface to be measured 9a projected by the laser beam, and in this embodiment, a CCD (charge coupled device) is used. The photographed striped pattern is stored in a recording means (not shown). Note that there is no need to use coherent light as a means for forming interference fringes built into this measuring head; for example, when forming moiré fringes, it is necessary to emit light from a normal light source such as a xenon lamp. It may be light that

The moving means 4 is for sequentially moving the center position of the measuring head 3 for each of the many divided regions of the surface to be measured 9a. In this embodiment, as shown in FIG. 3, when measuring the n-th divided area αn, for example, the adjacent divided areas
In order to make part of the measurement area β cover n+1, the center position Cn' of the measurement head 3 is moved so as to be slightly shifted from the center position Cn of the divided area αn. In order to perform the moving operation quickly and accurately, the moving means 4 of this embodiment uses the first moving means 10 for movement in the X-axis direction, and for movement in the Y-axis direction perpendicular to the X-axis. It is configured to be carried out by the second moving means 11. The first moving means 10 includes a support 6
It consists of a step motor 12 fixedly attached to the motor 12, and a screw shaft 13 rotated by the motor 12. Note that the screw shaft 13 is connected to the slider 14
It is designed to be screwed into a screw hole cut approximately in the center of the body. On the other hand, the second moving means 11 includes a step motor 15 fixed to the reference surface 1a and a screw shaft 16 rotated by the motor 15.

The control means 5 controls the light source 8 as well as the first
, the operation of the motors 12 and 15 of the second control means 10 and 11, and for main scanning, that is, movement of the measuring head 3 in the Drive control and width scanning, that is -Y
Regarding the movement of the stage 2 in the direction, the motor 15 is configured to be driven and controlled for a specific time at every predetermined time interval. Therefore, according to this embodiment, the first and second moving means 10 and 11 are efficiently driven by the control means 5,
That is, the main scanning and the width scanning are carried out by the first and second moving means 10, respectively.
By having 11 perform the movement, it is possible to carry out the movement operation in a very rational manner in the minimum amount of time. In the above description, the stage and observation head were each provided movably, but one may be fixed and the other may be moved two-dimensionally. Furthermore, the present invention is applicable not only to interferometers but also to moiré cameras and the like. In addition, when using a laser in this invention, a He-Ne laser with a wavelength of 633 μm or a laser with a wavelength of 8
Preferably, an 80 μm semiconductor laser is used.

[0015]

As explained above, according to the shape measuring device according to the present invention, the moving means is suitably and rapidly operated by electrical control of the control means to move the observation head to a predetermined position in each region of the surface to be measured. Since it can be mechanically moved to different positions in sequence, unlike conventional manual movement work, even if the surface to be measured has a larger expanse than the measurement aperture,
The surface to be measured can be measured continuously and accurately without any gaps. Furthermore, measurements can be performed extremely smoothly and quickly.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a shape measuring device according to the present invention.

FIG. 2 is a block diagram showing the state of connection of the control means to electrical components, etc. according to the present invention.

FIG. 3 is an explanatory diagram showing regions to be measured on each surface to be measured by the observation head according to the present invention.

[Explanation of symbols]

1 Base 1a Reference surface 9 Object to be measured 2 Stage 3 Observation head 4(10,11) Transportation means 5 Control means

Claims (1)

[Claims] 1. A light source, a stage movably provided with an object to be measured placed on the upper surface, and a stage that is movably provided with a surface to be measured of the object to be measured. a measurement head that is provided above the stage and movable along the stage and includes a measuring means for measuring stripes formed according to the thickness of the object to be measured; a means of movement for moving along a surface;
A shape measuring device comprising: a control means for controlling the operation of the moving means so that the measurement head sequentially measures (with some of the measurement areas of the surface to be measured overlapping)