Abstract: An optical filter is provided for use in color projection display imaging systems which utilize liquid crystal light valves for image modulation. The optical filter is a dichroic coating which separates light into different colors. The optical filter is located on a light transmissive surface of a color splitting device such as a Philips prism. The optical filter is formed from layers of at least two different dielectric materials including a high refractive index material, such as zirconium oxide and a low refractive index material such as aluminum oxide. The low refractive index material has an average refractive index of no less than about 1.6. The high refractive index material has an average refractive index which is sufficiently greater than the average refractive index of the low refractive index such that the average refractive index of the high refractive index material divided by the average refractive index of the low refractive index material yields a ratio that is greater than about 1.

Abstract: A spectral wavelength discrimination system and method for using are provided which allows the wavelength of a beam of radiation to be accurately determined using compact inexpensive optics and electronics. The system is particularly useful for identifying the emission wavelength of a multi-component marker system which includes a plurality of components having different wavelength ranges. The system comprises a wavelength selective beamsplitter, termed a Linear Wavelength Filter, that directs predetermined fractions of the beam at each wavelength into each of two output beams. The intensities of these output beams are measured. The measurements and selected system parameters, including the beamsplitter spectral characteristics and the detector sensitivity characteristics are used in a special algorithm for performing Fourier based wavelength-dispersive analysis. The unique solution of the Fourier based analysis is the wavelength of the beam of radiation.