Shape measurer with adjustable image magnifying power in two axes

Abstract

The shape measure has one light source to project to object to be measured, one electronic imaging device, such as one CCD camera, to take laser image, and one calculator to calculate the coordinate positions of various points. In the present invention, one curved reflector or one telecentric cylindrical lens combination is used in regulating the image scaling power in the laser projecting direction, and other cylindrical lens combination is used in regulating the image scaling power in the laser width direction to improve the resolution, which degrades with the increased distance during measurement. After precise optical analysis and design, the visible distance of CCD camera may become the effective measurement depth.

Description

technical field [0001] The invention relates to a shape measuring device for biaxially modulating the magnification of an image, which adopts the characteristics of a telecentric optical structure in an optical system to uniformize the resolution of the far and near, and is a high-resolution and uniform image-taking device. Background technique [0002] In the imaging device for general shape measurement, a fixed-focus lens is usually used to cooperate with a fixed-resolution and fixed-size CCD camera to have a fixed viewing angle in both vertical and horizontal directions, so when the distance from the object is closer, the range seen The smaller the distance, the greater the resolution; on the contrary, when the distance from the object is farther, the larger the range seen, the smaller the resolution. When the range of light (or surface) that the CCD camera can see in the direction of the projected light is larger than when it is perpendicular to the light (or surface), i...

AI Technical Summary

Problems solved by technology

[0003] Existing methods can already obtain higher resolution in the direction of projected light, but they cannot solve the fact that the resolution will become lower and lower as the distance from the light source gets farther and farther away. The problem of uneven resolution occurs when the When the resolution at short distances is sufficient, the resolution at long distances is insufficient; in addition, in the prior art, the resolution perpendicular to the direction of projected light is determined by the parameters of the CCD camera, so the selected focal length and object distance have determined the direction resolution

If you want to change the resolution perpendicular to the projected light direction, you can only change the object distance or focal length, but usually a shape measuring device has its desired object distance in operation, so the range of object distance that can be adjusted is relatively limited. Therefore, the focal length of the objective lens will probably be changed; whether it is to change the object distance or the focal length, the resolution of the projected light direction will also change accordingly, so it is necessary to change the anisotropic or anamorphic lens group parameter

Since the focal length of the objective lens directly determines the resolution of one axis, in fact, based on cost considerations, most of the imaging lenses use commercially available fixed-focus lenses, such as monitor lenses, whose focal length value is only a certain value, so the design must meet Two-axis resolution is difficult

[0004] like figure 1 Shown is a schematic diagram of the resolution of the existing non-modulated image magnification. A projected light plane 11 is projected onto the surface of an object 20 to be measured, and the situation presented by the reflected light 7 captured by the equidistant CCD pixels is completely Without adjusting the magnification of the image, the projected light direction has a fairly large field of view, but the resolution at the long-distance drops rapidly, and because the depth of field of the general imaging objective lens is very limited, the long-distance measurement accuracy is very poor, and it is almost useless

[0005] like figure 2 Shown is the existing U.S. Patent (No. 6,046,812) using a cylindrical mirror to improve the resolution schematic diagram, with a projected light plane 11 projected onto the surface of an object 20 to be measured, and the reflected light 7 captured by its equidistant CCD pixels The presented situation, where the use of cylindrical mirrors to shorten the field of view in the direction of the projected light, improves the resolution, but the resolution at the far end is still much lower than that at the near end

Images