Patent ID: 6181726
Filing Date: 2001-01-30
Classification: G02B

Abstract:
An air-spaced etalon filter comprising:a first optical element having a first optical surface which is sufficiently flat to maintain a required Finesse;a second optical element having a second optical surface disposed apart from said first optical surface; anda plurality of spacer elements having a high degree of uniform flatness, parallelism and thickness, coupled to said first and second optical surfaces for defining a gap and for maintaining said first and second optical surfaces in a high degree of uniform flatness, parallelism and distance apart throughout the gap,wherein said plurality of spacer elements are formed from a spacer substrate having a low coefficient of thermal expansion, such as fused silica, and a flatness of less than 0.5 nm RMS that facilitates said high degree of uniform flatness and parallelism of said first and second optical surfaces.