| 摘要 |
1,249,540. Radar. GENERAL ELECTRIC CO. 22 Dec., 1969 [27 Dec., 1968], No. 62395/69. Heading H4D. To determine a component V X , Fig. 2 of the velocity V of a moving object, the doppler shifts imparted to two beams of radiation, incident on the object along position vectors E 1 and E 2 having an angle bisector orthogonal to V x , and scattered along a common direction E s1 are differenced, said difference being proportional to said velocity component. The measurement is independent of any movement of the object perpendicular to V x . Thus to detect the velocity of a metal sheet 10, Fig. 3, leaving a mill and liable to wrinkling (perpendicular movement), a laser 18 emits a coherent beam which is split into two beams 11 and 13 which intersect at a common point 15 on the sheet. The beams make equal angles 0/2 with the perpendicular to the sheet, so that V x is the velocity of the sheet. The scattered radiation from the two beams is detected at 23 and therein mixed to produce the differential doppler frequency. Beam splitting semi-transparent and totally reflecting mirrors 22 and 24 may be incorporated in one solid optical block Fig. 4 having a semi-reflective face 30 and a totally internally reflecting back surface. As an alternative, a single beam of radiation 47, Fig. 5 may be incident on the sheet and the two differently scattered radiations detected by equally angularly offset means 48 and 52, 48 being a mirror and 52 being an optical mixer directing the combined radiation to the photodetector 54. |
