PURPOSE: To produce the phase grating optical low-pass filter having stable performance at a low cost by improving the working dimensional accuracy thereof by the simple method.
CONSTITUTION: An optical glass plate 12A is cut by a projecting part 22 of a trapezoidal shape in section of a diamond wheel 20 while maintaining the diamond wheel 20 at a prescribed height t1 with a fixing base 30 in the process for cutting the optical glass plate 12A constituting the phase grating optical low-pass filter, by which a groove 16 of the trapezoidal shape in section is formed on the optical glass plate 12A. The parts on both sides of the groove 16 of the optical glass plate 12A are cut by shoulder parts 14 on both sides of the projecting part 22 of the diamond wheel 20, by which the thickness of the optical glass plate 12A is uniformalized.
OKAYAMA HIROAKI
ONO SHUSUKE
