| 摘要 |
PURPOSE: To obtain a gauge interferometer which can be used within the maximum length measuring range and hasμm-level measurement accuracy by superimposing a measurement beam upon a reference beam on a position detector array and evaluating the intensity distribution on the detector array by using a program control method. CONSTITUTION: Light emitted from a light source 1 is split into a measurement beam A and a reference beam B trough a beam splitter 2 and the beam A is converged on a target 4 through an objective lens 3. The returning beam of the beam A is projected upon a diffraction grating 6 and a diode array 7 on the back of the grating 6 through a convergent lens 5. The reference beam B, on the other hand, is passed through a variable multiple reflector 8, reflected by a vibrating mirror 9, and reaches the grating 6 and array 7 where the beam B is superimposed upon the beam A. When a gauge interferometer is constituted in the above-mentioned way, an intensity change occurs on the array 7 and the position of the target 4 can be found from the maximum intensity of contrast. The position of the maximum intensity of contrast can be decided by automatically evaluating the signal outputted from the array 7 by means of an evaluating means 10 by using a program control method.
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