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TitleA Compact Combinatorial Device for Measurement of Nonlinearity of Radiation Detectors
Publication TypeJournal Article
Year of Publication2014
AuthorsSaunders, P., White D.R., and Edgar H.
JournalInternational Journal of Thermophysics
Pagination290 - 302
Date Published2014
ISSN0195928X (ISSN)
KeywordsCombinatorial devices, Combinatorial method, Combinatorial techniques, Degrees of freedom (mechanics), Geometry, glass, Least-squares fittings, Light emitting diodes, Neutral density filters, Nonlinearity, Optical instruments, Prisms, Radiation detectors, Radiation thermometry, Scattered radiations
AbstractA new compact computer-controlled device using a combinatorial technique for measuring the nonlinearity of radiation detectors is described. The device consists of two sets of four beam-splitter cubes optically cemented together and arranged so that radiation from a single source is split into four separate paths, then recombined after passing through one of five neutral density filters placed in each path. This allows for the measurement of 625 approximately equi-spaced inter-related flux levels based on only 16 unknown transmittance values. These can be solved for by least-squares fitting, leaving 609 degrees of freedom remaining to determine the nonlinearity of the detector. A novel aspect of the design is the use of neutral density glass plates optically cemented along all the external faces of the beam-splitter cubes, which act as beam dumps for any reflected or scattered radiation. The cube faces in the desired beam paths have clear glass plates with an anti-reflection coating applied at the wavelength of interest optically cemented to them. Operation at other wavelengths is achieved by simply replacing these plates with plates coated for the new wavelength. The performance of the device has been tested using a silicon photodiode with a collimated 650 nm LED as the source. The results demonstrate that the device is able to measure linearity to better than 1 part in (Formula Presented.). © 2014, Springer Science+Business Media New York.

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