QC 351 A7 no. 56 / The 13.7 -m Czerny -Turner spectrograph at the McMath Solar Telescope is evaluated with regard to polarization and image -forming properties. The ratio of the transmissivity of the spectrograph for incident light linear polarized parallel to the slit, to the transmissivity for light polarized perpendicular to the slit is determined as a function of wavelength. Values of this ratio range from 0.3 to 20. The diffraction grating is responsible. It is shown that spectrograph transmission as a function of polarization may cause large photometric and radiometric errors. This fact is not unique to this particular instrument. Two mechanisms appear to contribute to the polarizance of the grating. These are (1) the Rayleigh or Wood's anomalies, and (2) a vector wave interaction introduced because the groove dimension is nearly the same as the wavelength. Peak polarizance Xp occurs at the Wood's anomalies, and for X > groove depth it is found that the wavelength of peak polarizance Xp is given by
λp = (0.7) d cos(B)
where d is the ruling separation and O the grating angle. Photoelectric scans of the solar spectrum were made across several of the Wood's anomalies to obtain their profiles.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/621653 |
| Date | 15 June 1970 |
| Creators | Breckinridge, James B. |
| Publisher | Optical Sciences Center, University of Arizona (Tucson, Arizona) |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | Technical Report |
| Rights | Copyright © Arizona Board of Regents |
| Relation | Optical Sciences Technical Report 56 |
Page generated in 0.0021 seconds