JP2003075110A - Shape measuring device - Google Patents

Abstract

(57) [Problem] To provide an object of the present invention, even if the surface of an object to be measured has a very smooth surface and it is very difficult to focus on the surface of the object to be measured. It is an object of the present invention to provide a shape measuring device that can easily focus and efficiently measure the shape of an object to be measured. According to an aspect of the present invention, there is provided a shape measuring apparatus that measures a position coordinate at an arbitrary position on each surface of an object to be measured and measures a shape of the object to be measured. Illumination optical systems L1 to L4 capable of adjusting the focus and projecting the chart image onto the object 4 and observing whether the chart image projected from the illumination optical system is focused on the surface of the object 4 Optical system L4-L6 for
And a stage 5 capable of moving the DUT 4 at least two-dimensionally with respect to the illumination optical system,
A position coordinate at an arbitrary position on the measured object is measured from an adjustment amount when the chart image from the illumination optical system is focused on the surface of the measured object and the position of the stage.

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to shape measurement of an object to be measured, and more particularly, to heightening the shape of the object to be measured even when the surface of the object to be measured is a mirror surface. It can be measured with high accuracy. 2. Description of the Related Art Various methods have been proposed for measuring a three-dimensional shape of an object to be measured very precisely. In particular, it is well-known that a method of measuring a three-dimensional shape by moving a probe and detecting a position where the probe is in contact with the object to be measured or an image of the object to be measured by an imaging optical system is used. There is a method of measuring a three-dimensional shape of an object to be measured from an image formation state of an image. However, according to the former method using a probe, the device becomes complicated, and such a device cannot be easily obtained. In addition, the contact may cause deformation or damage of the measured object. In the latter method, an optical system having a small depth of focus such as an industrial microscope is used to perform focusing so as to focus on the surface of an object to be measured, thereby detecting a position in the field of view in the height direction. It becomes possible. Therefore, one feature is that it can be easily introduced into a manufacturing site or the like more easily than a method using a probe. [0005] However, if the object to be measured has a mirror surface or is transparent like glass, focusing becomes very difficult. Also,
When measuring a tilted portion, the illumination light is reflected in different directions by the tilted portion, so that it is difficult for the illumination light to enter an optical system for focusing. Accordingly, it is an object of the present invention to easily focus on a surface of an object to be measured even if the surface of the object to be measured has a very smooth shape and it is very difficult to focus on the surface of the object to be measured. It is an object of the present invention to obtain a shape measuring device capable of efficiently measuring the shape of an object to be measured. In order to solve the above problems, according to an aspect of the present invention, a position coordinate at an arbitrary position on each surface of a measured object is measured, and a shape of the measured object is measured. An illumination optical system that can adjust the focus and projects a chart image onto an object to be measured, and observes whether the chart image projected from the illumination optical system is focused on the surface of the object to be measured. And a stage capable of moving the object under measurement at least two-dimensionally relative to the illumination optical system, and a chart image from the illumination optical system is placed on the surface of the object to be measured. The position coordinates at an arbitrary position on the object to be measured are measured from the adjustment amount at the time of focusing and the position of the stage. According to the above-described embodiment, the object to be measured is arranged on the stage which can move two-dimensionally, and the chart image is projected on the object to be measured. Then, the illumination optical system is focused while confirming the chart image with the observation optical system so that the projected chart image is focused on the surface of the measured object. In the case of focusing, focusing can be performed very quickly because the presence or absence of focus can be confirmed while observing the chart image without observing the surface of the object to be measured. Then, from the adjustment amount at the time of focusing and the position of the stage, it is possible to obtain position coordinates for an arbitrary portion of the object to be measured. Data can be obtained. Next, the present invention will be described in detail in embodiments of the present invention. However, the present invention is not limited to this. Next, a shape measuring apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG.
It is a schematic structure figure of the shape measuring device of the present invention. The shape measuring device includes a light source 1, a chart 2, a half mirror 3
And an XY stage 5, a focusing mechanism 8, and position display means 9 for displaying a position on a measurement surface. Then, the DUT 4 is set on the XY stage 5. Then, as an illumination optical system, L1 to L4
, And lenses L4 to L6 as an observation optical system. L4 is a lens commonly used for both the illumination optical system and the observation optical system, and is an objective lens. These optical systems have the same lens configuration as those generally used for industrial microscopes, and these optical systems are housed in a lens barrel normally used for industrial microscopes. The lens barrel itself is vertically movable so that focusing can be performed. Further, in the shape measuring apparatus of the present embodiment, the chart pattern mask 2 is inserted in the illumination optical system. On the other hand, a mark chart 7 is provided in the optical path of the observation optical system. The chart pattern mask 2 in this embodiment employs a cross-shaped pattern centered on the optical axis. Then, the chart pattern mask 2 is
It is arranged at a position optically conjugate to the above. On the other hand, the marked line chart 7 is also arranged at a position conjugate with the surface of the DUT 4 in the observation optical system. In the shape measuring apparatus having such a configuration,
First, an arbitrary position of the DUT 4 is matched with the center of the optical axis of the illumination optical system. Then, the light source 1 is driven to emit light, and the chart pattern is projected on the measured object by the illumination optical system. Then, the measurer observes the image projected on the object to be measured by the observation optical system. At this time, when the projected image of the chart pattern is not focused on the surface of the DUT 4, the chart pattern is blurred when the chart pattern is observed by the observation optical system. Therefore, the focal length is adjusted using the focusing mechanism 8 so that the chart pattern becomes clear. Then, the focus position is adjusted while observing the chart pattern by the observation optical system so that the projected image of the chart pattern can be clearly observed by the observation optical system. Since a signal from an encoder (not shown) attached to the XY stage and a signal from an encoder (not shown) attached to the focusing mechanism 8 are input to the position display means 9, focus position adjustment is performed. Is completed, the XY position information and the focusing distance information displayed on the position display means 9 are read. From these two pieces of information, the position on the surface of the DUT 4 can be measured. By performing such a measurement method at a plurality of arbitrary positions of the DUT 4, the surface shape of the DUT 4 can be measured. In addition, even if the surface of the DUT 4 is a mirror surface or a transparent surface, since the image formed on the surface is observed by the observation optical system, the surface of the DUT 4 can be observed. Even if it is not in the state, the in-focus position can be detected. By the way, in such a shape measuring device,
The chart pattern reaches the eyeball 6 of the measurer with very low contrast. Therefore, in the present embodiment, the dark field chart pattern shown in FIG. 2 is used. FIGS. 2A and 2B show an example of a chart pattern. FIG.
(A) shields most of the portion corresponding to the light beam passing portion, and forms a transparent portion that is thin in a cross. By doing so, a thin cross-shaped shining line appears to emerge at the time of focusing, and focusing can be performed very easily. Note that, as shown in FIG. 2B, a linear pattern in a vertical direction and a horizontal direction may be formed. The method of using the shape measuring device according to the present invention is not limited to this. In addition, it can also be used to detect the focal length (curvature radius) of a concave mirror or a convex mirror, to detect the center of a concave mirror or a convex mirror, and to detect the distance between transparent optical elements. However, a convex mirror cannot measure a radius of curvature larger than the working distance of the objective lens. When measuring the focal length of the concave and convex mirrors, the position of the illumination optical system is adjusted so that the chart pattern projected on the reflecting surface of the concave or convex mirror using the shape measuring apparatus of the present invention is focused. Adjust and measure the focus position. Next, the illumination optical system is moved so that the image formed by the illumination optical system is substantially at the focal position of the concave or convex mirror. Then, while observing the chart pattern image with the observation optical system, the position of the illumination optical system is adjusted until the image is focused, and the focus position is measured. Finally, the difference between the in-focus position when the chart pattern is imaged on the mirror surface of the concave or convex mirror and the position when the chart pattern is focused on the focal position of the concave or convex mirror is obtained. It is possible to accurately obtain the focal length of the convex mirror. When the concave or convex mirror is to be centered next, the side surface of the concave mirror is placed on a jig having a V-shaped cross section. Then, as performed when measuring the focal length, an image of the chart pattern projected from the illumination optical system of the shape measuring apparatus of the present invention is formed at the focal position of the concave mirror. Next, the concave mirror is rotated while the side surface of the concave or convex mirror is in contact with the V-shaped portion of the jig. When the concave or convex mirror is rotated, whether the center of the optical axis coincides with the center of the outer peripheral surface of the concave or convex mirror is measured by whether or not the image of the chart pattern can always be observed at the same position by the observation optical system. It is possible to do. Further, the shape measuring apparatus according to the present invention can be used in the following usage forms. For example, when a plurality of concave or convex mirrors are arranged in one subject,
The distance between the optical axes of the concave or convex mirrors can be measured. First, an image of a chart pattern projected from the illumination optical system is formed at a focal position of a concave or convex mirror to be a reference. After capturing this aerial image with the observation optical system and focusing so that the image of the chart pattern is clearly visible,
The image of the chart pattern of the illumination optical system and the image of the pattern mask of the observation optical system are completely overlapped. If they completely overlap, the optical axis of the concave or convex mirror and the optical axis of the measuring device will overlap, so the position of the XY stage is read by the encoder. Next, the XY stage is driven and moved to the focal position of the concave or convex mirror to measure the distance between the axes. At this position, the position of the focal point is captured in the same manner as that performed first at the focal position of the concave or convex mirror to be used as a reference. By detecting the difference between the position data at this time, the distance between the optical axes of the two concave or convex mirrors can be measured. As described above, according to the present invention described in the claims, even if the surface state of the object to be measured for shape measurement is transparent or mirror-finished, the surface of the object It becomes possible to measure each coordinate position on the upper part. Therefore, it is possible to obtain accurate shape data of the surface of the object to be measured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a shape measuring device according to an embodiment of the present invention. FIG. 2 is a diagram showing a configuration of a chart pattern mask used in the shape measuring apparatus according to the embodiment of the present invention. [Description of Signs] 1 ... Light source 2 ... Chart pattern mask 3 ... Half mirror 4 ... Measurement object 5 ... XY stage 6 ... Measurer's eyeball 7 ... Marked line chart 8 ... Focusing mechanism 9 ... Position display means

Claims (1)

Claims: 1. A shape measuring apparatus for measuring position coordinates at an arbitrary position on each surface of an object to be measured and measuring the shape of the object to be measured, wherein a focus adjustment is possible and a chart image is provided. An illumination optical system for projecting the object to be measured, an observation optical system for observing whether a chart image projected from the illumination optical system is focused on the surface of the object to be measured, and the object to be measured A stage that is movable two-dimensionally relative to the illumination optical system, and an adjustment amount and a position of the stage when a chart image from the illumination optical system is focused on the surface of the object to be measured. A shape measuring device for measuring a position coordinate at an arbitrary position on an object to be measured.