Narrow-band wide-angle tunable stages of an optical filter (based on two-beam interferometers with semitransparent metallic layers)

This paper discusses the possibility of creating narrow-band wide-angle and tunable stages of an optical filter, based on two-beam interferometers with semitransparent metallic layers. The use of such multiple two-beam interference of light at metallic semitransparent layers makes it possible to simplify the layout of the sequential filter stages. To stabilize the alignment and to make it possible to tune over the spectrum, it is proposed to cement or rigidly attach the main elements into one unit with air gaps in each stage. The gaps allow alignment elements to be placed in them and make it possible to tune the stage in a wide spectral range. The main formulas are obtained for a two-beam interferometer with a wide angular field of view, along with a version of these formulas for a stage with gaps. A working prototype of a cemented first stage has been created and tested.