CIRCULAR WAVE-REVERSING INTERFEROMETER Russian patent published in 1997 - IPC

FIELD: measurement technology; checking spherical and aspherical (slightly other than spherical) surfaces of optical parts for correct shape. SUBSTANCE: double-frequency laser source 1 and collimator lens 2 produce collimator beam. Prism-cube 3 with polarized light-splitting layer bifurcates beam into operating and reference ones. Both arrive at viewing system with minimum loss due to reverse circular trace of waves , and photodetector 14 of this system, whose drive is connected to bidirectional bus 19, scans the field by interference in plane joined through projection system (positive elements 7, 9 and negative one 10) to surface 20 under check. Picked off output of photodetector 14 is signal whose phase varies with respect to that of reference signal picked off photodetector 15. Light-sensitive surface of photodetector 15 is joined with that of photodetector 14. Operating and reference signals are compared in phase-difference metering unit 16. Controller 17 functions to process data and to control operation of scanning photodetector 14 and phase-difference metering unit 16. This controller also computes topography of surface under check on display 18 by phase difference. Data exchange among unit 16, scanning photodetector 14, controller 17, and display is made over bus 19. EFFECT: improved accuracy and capacity of check due to automatic control based on optical heterodyning. 1 dwg