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1 October 1990 Goniometer-spectrometer for index of refraction measurements from the near UV through the near IR
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Abstract
The Ml I erWede Goni ometer-Spectrometer Model 2 is a medi urn-high accuracy instrument for the determination of prism angles and index of refraction in the visible wavelength range (400-700nrn) With its automatic Heidenhain rotary encoder the instrument is capab''e of absolute accuracy to I O arcsec for prism angle measurements and i x I 05 for index of refraction measurements. Recently we have developed a modified version of this instrument to provide absolute index of refraction measurements in the wavelength range from the UV through the near IR (254nm-2325 nm). The absolute accuracy for index of refraction measurements in the range is j INIRQDILTIQt4 The classical methods of Rudberg and Franhoer are still the most accurate means of determining the absolute index oT refraction or bulk optical materials. Both methods utilize a collimator and telescope pair which are both focused at inflnity. The former is normally flxed and the latter is mounted on a goniometer arm equipped with a precision graduated circle to provide absolute angular position of the telescope. The collimator is used to project the slit image o various spectral lines through a prism made from the material to be tested Usually spectral lamps are used for the light sources but lasers have also been used. The telescope and the sample prism are each rotated about the vertical axis of the goniometer so that each is set at proper angle to produce a minimum angle of deflection of the projected slit image with the desired wavelength. The goniometer arm and telescope are then fine-adjusted so that the slit image 32 / SPIE Vol. 1327 Properties and Characteristics of Optical Glass II (1990)
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Gerd Joachim Ulbrich and Jens Trede "Goniometer-spectrometer for index of refraction measurements from the near UV through the near IR", Proc. SPIE 1327, Properties and Characteristics of Optical Glass II, (1 October 1990); https://doi.org/10.1117/12.34754
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