METHOD OF MANUFACTURING PRECISION CIRCULAR OPTICAL SCALES WITH DECREASED ANGLE ERRORS Russian patent published in 2014 - IPC G02B27/32 

FIELD: instrumentation.

SUBSTANCE: workpiece is degreased, cleaned, the first heat treatment is carried out and the positive photoresist is applied on the basis of diazo compounds. The second heat treatment, exposure and development are carried out, followed by washing with water of the rotating workpiece. The chromium masking material is applied to the workpiece in vacuum, and the protective photoresist layer is removed with an organic solvent. During exposure the amplitude of the second harmonic of the angular error dependence of location of axes of strokes is changed by changing the angle of slope of plate of exposure installation relative to the axis of the incident actinic radiation. During the synthesis of the used photomask its phase is changed so that the second harmonic of the angular error dependence of location of diameters of axes of strokes caused by the photomask is in antiphase of the second harmonic of the angular error dependence of location of diameters of axes of strokes made by the exposure operation.

EFFECT: reduction of the accumulated error of location of diameters of axes of strokes.