RESEARCH ON THE DEVELOPMENT OF ULTRA NARROW BAND FILTERS FOR OPTICAL AND SPECTROPHOTOMETRIC USE.
Rept. for 1 Jan 59-30 Dec 61,
SPECTROLAB INC NORTH HOLLYWOOD CALIF
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Investigations carried out by Spectrolab on the research and development of ultra narrow band filters for optical and spectrophotometric use are described. Filters with bandwidths of approximately 0.5 Angstroms were desired for the visible region. A theoretical study was made into the various types of light filters with respect to their possibilities as narrow band filters. Two approaches were considered for the development of very narrow band filters and some prototypes were successfully prepared. Once the filters were made, difficulties ensued in the measurement of their parameters. Several attempts were made to develop suitable techniques for such measurements. A method is described which is capable of giving a semi-qualitative evaluation of these filters. Further work in correlating theory and experiment is necessary in this area. An investigation was made regarding the feasibility of producing narrow band filters in the ultra violet and infrared regions. A materials investigation was conducted for appropriate film components in these regions. Satisfactory films have been produced in the 3000 to 4000 A region. Below this region the rare earths have demonstrated promising results but additional study and research is required. A variety of materials exist for the production of infrared interference filters but time and expense prohibited the preparation of narrow band filters in this region. Author