GB1534894A - Magneto-optic analysers - Google Patents

Abstract

1534894 Magneto-optic analyzer HITACHI Ltd 15 March 1976 [14 March 1975 7 May 1975 20 June 1975 29 Sept 1975 14 Nov 1975] 10317/76 Heading G1A A magneto-optic analyzer for detecting and identifying atoms in a sample 3 comprises a light source 1, e.g. a laser, a birefringent polarizer 2 from which the light emerging in two directions 9, 10 has different planes of polarization, a reflector 6 and a detector 5 positioned to receive forward scattered light from the sample 3 along a path 11, this being separated from the incident light path by the polarizer 2 following the rotation of the plane of polarization of the scattered light during its double passage through the sample 3 by a magnetic field produced by means 7, 8. Rotation of the polarizer 2 by motor 13 produces amplitude modulation of the light received by detector 5 the A.C. component of which represents the forward scattered light and can be separated electronically from the noise signal produced by leakage light through the polarizer. Leakage light may be reduced per se by wavelength selective filters, prisms or diffraction gratings arranged along the optical path or combined with reflector 6. In a further embodiment Fig. 6 (not shown) a further polarizer (2') transmits only scattered light to detector 5 which has a plane of polarization orthogonal to that of the incident light on the sample. Second detectors (10) Fig. 7 and 5-1 Fig. 8 (not shown) may be positioned to receive light from the sample not deflected by the polarizer (2) and provide a compensating signal for fluctuations in light level caused by foreign atoms &c. in the sample. Still further improvements in signal-noise ratio may be achieved by modulating the light from the sample by a chopper (13) Fig. 9 (not shown), by angularly oscillating the reflector (6), or by rotating the magnetic field Fig. 12 (not shown). The signals from detector 5 are then passed to demodulating circuits, Figs. 11a-11c (not shown) and (Fig. 12).