PURPOSE: To implement a compact configuration and light weight, by stacking a mirror and an A0 element, which split a light beam in a lightguide comprising a thin film of a derivative as a unitary body, and arranging an element, which converts linearly polarized light into a circularly polarized light, at the outside of a light sending end.
CONSTITUTION: Parallel light 23 comprising a TE wave does not satisfy Bragg conditions with respect to an A0 element 24. Therefore the light is advanced on a straight line and converged by a lens 25. An isotropic spotlight point is located on a cleavage plane 26. A collimator system 27 is placed at this point. Then parallel light rays are formed in a free space. A λ/4 plate 28 is provided in the light path and the linearly polarized light is converted into the circularly polarized light, which is sent to a material to be measured. The reflected light from the material to be measured passes the λ/4 plate 28 again. The light is returned to the thin film lightguide by the collimator system 27, made to be the TM wave, and advanced in the direction of 23. When the light is converted into the TE wave by the A024, the light undergoes Bragg diffraction, becomes light rays 29 by a lens 22, and is converged on a detector 30. Meanwhile, light 32 is projected on the detector 30 from a mirror 31.
SETSUNE KENTAROU
WASA KIYOTAKA
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