| 摘要 |
1,200,758. Photo-electric analysis. ELTRO G.m.b.H. & CO. GES FUR STRAHLUNGSTECHNIK. Aug.3, 1967 [Aug.25, 1966], No.35632/67. Heading G1A. The dispersive or diffractive effects of a medium is determined by observing the effect upon a diffraction pattern generated by a grating when the medium is interposed between the grating and the illuminating source of monochromatic coherent light. In Fig. 2 light from a laser passes through a medium 2, such as the atmosphere, where it is rendered largely incoherent to illuminate a diffraction grating 5. The diffraction pattern generated by the grating is viewed periodically with the aid of a rotating mirror 6, by a telescope 10 containing a photo-multiplier 16. Different orders of the pattern are selected by rotating the telescope about an axis through the grating. In alternate periods the telescope receives a reference beam via mirror 4 and glass fibre light guide 13. The two beams are balanced by a wedge 19 variably positioned in the reference beam according to the output of the photomultiplier. The position of the wedge indicates the intensity of that part of the diffraction between being viewed. In another embodiment Fig. 1 (not shown) there is no reference beam. |
