Measurement method for locating the edge of the test object using laser

Abstract

A measurement method for locating the edge of an object under test using laser includes: setting up a laser unit, a slit unit, and a screen unit; placing a length measuring tool on the screen unit corresponding to the slit unit; projecting an interference fringe onto the screen unit by passing a laser light through the slit unit; taking the center of one of the bright fringes or the midpoint between the first dark fringes of another interference fringe as a center position of the interference fringe; and determining whether to add or subtract half the slit width to a scale value corresponding to the center position based on whether the object under test is located in the positive or negative axial direction of the length measuring tool relative to the obstruction, thereby obtaining a projection position of the edge projection of the object under test. This allows the edge projection position to be found without the need for dedicated calculation software.

Claims

1. A measurement method for locating the edge of an object under test using laser, comprising: sequentially and adjacently arranging a laser unit, a slit unit, and a screen unit; and arranging a length measuring tool on the screen unit corresponding to the slit unit, the length measuring tool having a plurality of scale lines; the slit unit including an adjacent object under test and a block, the object under test and the block forming a single slit with a slit width; the laser unit emitting a laser light, the laser light passing through the single slit and projecting an interference fringe on the screen unit, and an extension direction of the length measuring tool parallel to a fringe arrangement direction of the interference fringe; taking the center of a central bright fringe of one interference fringe, or the midpoint between a first dark fringe of another interference fringe, as a center position of the interference fringe; if the object under test is located in the positive direction of the length measuring tool relative to the block, then the center position corresponding to a scale value of the scale line plus half the slit width is a projection position of the edge of the object under test projected onto the length measuring tool. If the object to be measured is located in the negative direction of the length measuring tool relative to the obstruction, then the center position corresponds to the scale value of the scale line minus half the slit width, which is the projection position of the edge of the object to be measured onto the length measuring tool.

2. The measurement method for locating the edge of an object under test by laser as described in claim 1, further comprising maintaining the slit width, changing the relative position of the laser unit and the slit unit so that the laser light passes through the single slit at different positions of the edge of the object under test, thereby obtaining at least two projection positions; taking one of the projection positions as a reference position, the reference position as the origin of the coordinate axis, calculating the linear distance between the remaining projection positions and the reference position to obtain the coordinate position of the edge of the object under test, and finally comparing the change in the coordinate position of the same point on the edge of the object under test before and after wear to obtain at least one wear amount.

3. The measurement method for locating the edge of an object under test using laser as described in claim 1, further comprising: capturing an image of the interference fringes and the length measuring tool using an image capturing unit to form a fringe image; magnifying the fringe image at a first magnification to form a first magnified image, the first magnification being the largest positive integer in which the central bright fringe can still be observed to have an edge on each side of the fringe arrangement direction; taking a center line perpendicular to the fringe arrangement direction at the exact midpoint of the two edges; marking the center line on the fringe image; and magnifying the fringe image near the center line at a second magnification to form a second magnified image. The image has a second magnification factor of a positive integer between 5 and 15. Comparing the length measuring tool and the center line in the second magnified image, when the center line and one of the scale lines of the length measuring tool are separated by a distance difference, this distance difference is divided by the second magnification factor to obtain an original distance difference. When the center line is located in the negative direction of one of the scale lines, the original distance difference is subtracted from the scale value corresponding to that scale line to obtain the center position of the striped image. When the center line is located in the positive direction of one of the scale lines, the original distance difference is added to the scale value corresponding to that scale line to obtain the center position of the striped image.

4. The measurement method for locating the edge of the object to be measured by laser as described in claim 3, further comprising: when the distance difference between the center line and one of the scale lines is 0 units, directly taking the scale value corresponding to one of the scale lines as the center position of the stripe image.

5. The measurement method for locating the edge of the object under test by laser as described in claim 3, further comprising: after observing two edges in the first magnified image, taking an edge line perpendicular to the stripe arrangement direction on each of the two edges; comparing the length measuring tool in the first magnified image with the two edge lines; when the edge line is at a distance difference from one of the scale lines, dividing the edge distance difference by the first magnification to obtain an original edge distance difference; when the edge line is in the negative direction of one of the scale lines, subtracting the original edge distance difference from the scale value corresponding to the scale line to obtain an edge position of the stripe image; when the edge line is in the positive direction of one of the scale lines, adding the original edge distance difference to the scale value corresponding to the scale line to obtain the edge position of the stripe image; and subtracting the two edge positions and taking the absolute value to obtain the width of a central bright stripe of the stripe image.

6. The measurement method for locating the edge of the object to be measured by laser as described in claim 3, further comprising: after taking the center line, observing the other two edges of the central bright fringe perpendicular to the fringe arrangement direction, taking another center line parallel to the fringe arrangement direction at the very center of the other two edges, and the intersection of the center line and the other center line being a center point of the fringe image.

7. The measurement method for locating the edge of an object to be measured by laser as described in claim 3, further wherein the first magnification of the stripe image is a positive integer between 6 and 10.

8. The measurement method for laser positioning of the edge of the object to be measured as described in claim 1, further wherein the slit width is between 0.1 and 0.25 mm.

9. The measurement method for laser-locating the edge of an object to be measured as described in claim 1, wherein, The barrier is made of one of the following materials: polymer, metal, or ceramic.

10. The measurement method for laser-locating the edge of an object to be measured as described in claim 1, wherein, The barrier is made of plaster.

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