Optical filter

An optical filter comprising:

• a plate of colored glass having band-pass filter characteristics and defining a transmission band over a visible region of relatively narrow width, and
• an interference multilayer film formed over the colored glass plate and having a reflection band for removing a predetermined range of wavelengths from the transmission band so that the optical filter defines a specified transmission band,
• the interference multilayer film including at least two unit layers and a first intermediate low refractive index material layer interposed therebetween, each of the unit layers including two high refractive index material layers and a second intermediate low refractive index material layer interposed therebetween,
• wherein the second intermediate low refractive index material layer has an optical thickness of .lambda..sub.0 /2, and the first intermediate low refractive index material layer and the high refractive index material layers have an optical thickness of .lambda..sub.0 /4, where .lambda..sub.0 is a dominant wavelength for the interference multilayer film.