PURPOSE: To enable a parameter control for a production process by conducting an on-line measurement of a surface roughness of a product with a double-beam heterodyne optical interferometer connected to the production process.
CONSTITUTION: A coherent monochromatic output optical beam 21 is guided to an acouto-optical modulator 22, to generate a zero order beam 23 by an output form a frequency oscillator 24 of a frequency fm (40MHz) and a first order output beam 25 subjected to a frequency shift by a magnitude of a frequency fm relative to the zero order beam. The beam 25 is polarized into an orthogonal line from polarized measurement beam 30, 32 in a refractive polarizer 26 and radiated on a surface 34 to be measured. A reflected light from the surface is synthesized into a single measurement beam 27, the beam is again subjected to a frequency shift by a magnitude twice fm in the modulator 22 to form a measurement beam 29, the measurement beam and the beam 23 are dispersed into the orthogonal line form polarized beams 38, 40, including a coherent component in a polarized beam splitter 36 and detected 42, 44 and a phase shifting is calculated in a computer 46. Information on the phase shifting indicating a roughness of a measured surface is fed back to the production process, in order to keep a product within parameters.
TEIMOSHII BII KAARUSON
RICHIYAADO DABURIYUU PIITAASON
SUTEIIBUN EMU DENZAA
ROBAATO PII GUROSHIEN JIYUNIA
MAIKERU JIEI SHIYUMEINDA
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