JPS54141149A - Interference filter - Google Patents

Abstract

PURPOSE: To achieve the improvement in performance by specifying the film thickness relations of materials of high and low refractive indices to be laminated on a transparent substrate.

CONSTITUTION: High refractive index materials 5a thru 5d such as cerium oxide or other of about 2.35 in refractive index and low refractive index materials 6a thru 6c such as magnesium fluoride or other of about 1.38 in refractive index and laminated on a transparent glass substrate 4 by continuously varying film thicknesses in the direction perpendicular to the advancing direction of light while maintaining the relations of nHdH∝nLdL where the film thicknesses of the high refractive index materials 5a thru 5a are let to be dH, their refractive indices to be nH, the film thicknesses of the low refractive index materials 5a thru 6c to be dL and their refractive indices to be nL. Then, wavelength light of about 0.7μm transmits through one end part Ta of the glass substrate 4 and wavelength light of about 1.1μm at the other end part Tb, whereby the characteristics of difference spectral spectra may be continuously obtained depending upon the places used.

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