Laser gyrometer

Abstract

Abstract 1,237,663. Lasers. COMPAGNIE GENERALE D'ELECTRICITE. 5 May, 1969 [6 May, 1968], No. 22845/69. Heading H1C. [Also in Divisions H3-H5] Specification describes a ring laser gyrometer, whereas instead of using the simple relation: between the angular speed # imparted to the gyrometer and the frequency difference #f, between the contrarotating light beams 4(f 1 ) and 5(f 2 ), Fig. 1, K being a constant, the following relation is used, involving the intensities I 1 and I 2 of the two beams: A, B, C, D and K being constants. The second term may be ignored and the remainder simplified: Thus photo detectors 11 and 10 behind partly transparent mirror 3 produce signals respectively representing the intensities I 1 and I 2 of the beams 4 and 5 and beam combining mirrors 6, 7 and 8 and non-linear photo detector 9 produce a signal having the difference frequency #f of the two beams. The three detector outputs are fed to a computer 12, shown in detail in Fig. 2. The intensity signals I 1 and I 2 are summed at 14 and the sum signal fed to the control input of a variable frequency multiplier 15. The detector signal at frequency #f is frequency multiplied in means 16 and 19 by respective factors # and α. The resultant signal at frequency #.#f is fed to 15 which thereby produces a signal at frequency #.#f.(I 1 I+2). Said signal and the signal at frequency α#f from means 19 are fed to respective cycle counters 18 and 17, which, by counting the number of cycles occurring in equal predetermined time intervals -established by clock 20, produce signals proportional to -the respective frequencies. Said signals are subtracted in means 21 to produce an output signal proportional to #F, and to #.

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