Abstract

A theory is presented for metal light pipe spectroscopy in the infrared. Methods are described for producing sensitive spectra of thin films and powders inside the pipe. Propagation of infrared radiation down the pipe is analyzed. Sensitivities and resultant spectral shapes are predicted. There is a discussion about how to get optimum signal-to-noise ratios for instrument drift-limited spectra typical of FT-IR spectroscopy in the present application. Considered in the optical theory are the effects of skew rays, effects of light scattering, effects of pipe bending, and the presence of absorbing gasses. The method is predicted to be ideal for monolayer absorption spectroscopy.

Far Infrared Transmission through Metal Light Pipes*

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Ray Traces through Hollow Metal Light-Pipe Elements

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Transmittance of skew rays through metal light pipes

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Custom-built light-pipe cell for high-resolution infrared absorption spectroscopy of tritiated water vapor and other hazardous gases

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Opt. Express 27(12) 17251-17261 (2019)

Transmission of submillimeter waves through metal light pipes

Ensheng Fu
J. Opt. Soc. Am. B 13(4) 702-705 (1996)