Patent ID: 7002696

Claim:
An optical band pass device, comprising: a. a first substrate having a very low absorption loss including an inner surface and an outer surface; said inner surface thereof having a very high reflective coefficient of r1; b. a second substrate having a very low absorption loss including an inner surface and an outer surface; said inner surface thereof including: a transmission-optimized optical portion to facilitate input of light beams into said device and a reflective portion having a reflective coefficient of r2 wherein r1 is greater than r2; said outer surface thereof having a transmission coefficient of t to facilitate input and output of light beams in and out of said device; said second substrate mounted parallel to said first substrate with respective inner surfaces facing each other; c. a beam collimating element positioned to guide an input light beam to travel through said optical portions of said second substrate, to: 1) hit a first point on said inner surface of said first substrate, 2) reflect off of said first point, at a near normal incidence angle, towards a second point on said reflective portion of said inner surface of said second substrate, said second point spaced from said optical portions so as not to interfere with said input light beam, 3) hit said second point and a) partially reflect off of said second point towards said reflective portion of said inner surface of said second substrate such that there is no interference of reflected beams within said device and b) partially travel through said respective surfaces of said second substrate to generate said one of said output light beams; d. an optical medium having a predetermined refractive index located between said inner surfaces of said first and second substrates; and; e. an optical converging element spaced from said outer surface of said second substrate for converging said output light beams incident thereon; and; f. a displacement transducer for measuring the changes in the spacing between said inner surfaces of said first and second substrates; said displacement transducer to generate a input signal for a controller g. a controller for monitoring the tunable operation of said interferometer using said input signal generated by said displacement transducer.