| 摘要 |
PURPOSE:To prevent disturbance in thermal equilibrium and to make it possible to shorten a time for measurement in a plane and the like, by arranging lenses having an equal focal distance between a laser oscillator and a sample, whose absorptivity is measured, and contracting and expanding the diameter of laser light. CONSTITUTION:Lenses 2 and 3 have the equal focal distance. The outer diameter of the adjusting lens 3 is twice the outer diameter of the lens 2. Both lenses 2 and 3 are held on an optical rail 11. The lens 3 can set at twice the focal distance of the lenses with respect to the parallel laser light from a laser oscillator 1. The diameter of the measuring laser light is condensed after the light passes through the lens 2. The diameter is recovered to the original diameter again through the lens 3, and the parallel light is obtained. At this time, the lens 3 is moved back and forth with respect to the lens 2, and the diameter of the measuring laser light is contracted and expanded. In this way, the diameter of the measuring laser light at a sample 5 is arbitrarily changed. The change is temperature of the sample is measured with a thermocouple 7. The transmitting power and the like of the laser light with respect to the sample 5 are obtained. The absorptivity of the sample 5 is computed by a two-slope method.
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