Crosswise subtracted differential confocal paraboloid peak curvature radius measurement method
A differential confocal and radius measurement technology, applied in measuring devices, instruments, optical devices, etc., can solve the problem of low measurement accuracy of the curvature radius of the paraboloid apex, improve the sensitivity of fixed focus and signal-to-noise ratio, and eliminate common mode Effects of Noise, High Focus Measurement Accuracy
Active Publication Date: 2019-06-14
BEIJING INSTITUTE OF TECHNOLOGYGY
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[0007] The purpose of the present invention is to solve the problem that the measurement accuracy of the radius of curvature of the apex of the paraboloid is not high, and to provide a method for measuring the radius of curvature of the apex of the paraboloid with a lateral subtraction differential confocal. Virtual pinhole lateral subtraction detection to sharpen the confocal characteristic curve of the defocus detection optical path system, and to realize the differential confocal of the measured surface through the differential subtraction processing of the pre-focus and post-focus sharpening confocal characteristic curves of the dual optical path detection Bipolar fixed focus measurement, through the linear fitting of the differential confocal fixed focus curve to improve the focus position capture accuracy, and then realize the high-precision measurement of the curvature radius of the paraboloid vertex
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Embodiment 1
[0037] as attached Figure 5 As shown, the measurement steps of the lateral subtraction differential confocal paraboloid vertex curvature radius measurement method are:
[0038] 1) Start the measurement software of the main control computer 28, turn on the laser 32, and the light emitted by the laser 32 passes through the microscope objective lens 33 and the pinhole 34 to form a point light source 1. The light emitted by the point light source 1 is irradiated on the parabolic mirror 5 to be measured after passing through the beam splitter 2 , the collimator lens 3 , the measuring objective lens 4 and the plane half mirror 35 .
[0039] 2) Adjust the measured parabolic mirror 5 so that it has a common optical axis with the collimating lens 3, the measuring objective lens 4 and the plane half-mirror 35, and the measuring objective lens 4 converges the parallel light beams emitted by the collimating lens 3 into a measuring beam and irradiates it on the subject On the measured pa...
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The invention belongs to the technical field of optical precision measurement, and relates to a crosswise subtracted differential confocal paraboloid peak curvature radius measurement method. In the method, faculae detected by detectors separately in front of and behind a focus in a differential confocal detector are crosswise subtracted by using different sizes of virtual pinholes, and thus a sharpened crosswise subtracted confocal response curve is acquired; the two crosswise subtracted confocal response curves are subjected to differential subtraction to acquire a crosswise subtracted differential confocal response curve; surface peak and focus positions of a parabolic mirror under test are accurately determined according to the zero crossing point of the crosswise subtracted differential confocal response curve, and thus the accurate value of the peak curvature radius of the parabolic mirror under test is acquired. According to the method provided by the invention, the slope of thelaser differential confocal light intensity response curve, which is subjected to crosswise subtraction, close to the zero crossing point is more than that of the traditional differential confocal light intensity response curve, so that the focus fixing sensitivity is high, and the measurement accuracy is improved; and the anti-environmental interference ability is strong. The method is high in measurement accuracy and strong in anti-environmental interference ability.
Description
technical field [0001] The invention belongs to the technical field of optical precision measurement, and relates to a method for measuring the radius of curvature of the apex of a paraboloid by lateral subtraction and differential confocal, which can be used for high-precision detection of the radius of curvature and focal length of the apex of the paraboloid. Background technique [0002] Focusing accuracy is the main factor affecting the measurement of the radius of curvature and focal length of a paraboloid. However, the traditional measurement method is limited by the diffraction limit and cannot continue to improve the focusing ability of the beam. The invention improves the precision of focusing by using the laser differential confocal focusing method of lateral subtraction, so as to realize the high-precision measurement of the radius of curvature of the paraboloid and the focal length. [0003] The paraboloid can reflect the point light source at its focal point int...
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Inventor 邱丽荣郝群肖阳赵维谦
Owner BEIJING INSTITUTE OF TECHNOLOGYGY