Automatic Recording Laser Interferometer for Line Standards up to 2 m

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Abstract
A description is given of an automatic recording laser interferometer for calibrating line standards up to 2 m based on Eppenstein's principle, and various factors which limit the measuring accuracies are also investigated in detail. This fringe-counting interferometer uses two corner cube reflectors. One reflector is mounted with the objective of a photoelectric miscroscope on a carriage which moves at a uniform speed of 10 to 300 mm/min on an air track. An electric pulse, which corresponds to the center of a graduation line and is a gate signal for counting interference fringes, is produced by the zero crossing method from the derivative of a signal obtained when the graduation line image goes across a slit. The reflectors generate two different interference fringes in phase quadrature by using their polarization properties in reflection, so that fringe resolving power is raised to λ/16. The experimental results on line standards show that the standard deviation of a graduation line positioning is 0.04 μm and the accuracy of measurement on a 1 m line-interval is 0.08 μm in standard deviation.