Abstract
A new device is described with which the calibration of a standard scale up to 1000 mm long can be made in terms of interference fringes in an hour’s run. A standard scale on a carriage is translated longitudinally with uniform speed of 5 mm/min. Fringes produced by a Michelson interferometer are changed to a train of electric pulses that measures the translation with the unit of a quarter of wavelength used (5461 Å), and these pulses are accumulated on a counter successively. An impulse is produced by a fixed photoelectric microscope at every passage of graduation lines across the microscope axis. At every moment when the impulse comes from the microscope, the immediate content of the counter is taken out and printed automatically. A maximum of six photoelectric microscopes are used in tandem to extend the limited coherence length, and the batches of data are shown to be connected without introducing any appreciable errors. Thus a single run over 300 mm has made it possible to calibrate all graduations with a total accuracy of ±0.1 μ.
© 1964 Optical Society of America
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