METHOD FOR MANUFACTURING DIFFRACTIVE OPTICAL ELEMENT

摘要

Disclosed is a method for manufacturing a diffractive optical element in which heat generation from the inside of an insulating substrate can be reduced to stabilize an etching rate. Also, disclosed is a method for manufacturing a diffractive optical element comprised of an insulating substrate which is provided with projections and depressions on its surface.  The method comprises measuring the electrical resistivity of the insulating substrate and selecting an insulating substrate having an electric resistivity above a predetermined value, and dry-etching the insulating substrate selected in the selecting process to form projections and depressions on the surface thereof.