Design, construction, and performance data are given for a vacuum grating spectrometer which has been used in the frequency range 300–10 cm−1. The Czerny–Turner optics used have proved advantageous for high-resolution far infrared spectrometers. Use of recently developed radiation filtering techniques, light pipes, and light cones lead to a very simple and convenient spectrometer. A sample volume to path length ratio much lower than those found for conventional infrared gas sample cells is possible using light-pipe sample cells. The length of such sample cells may be easily extended without the additional optics needed for conventional long path length sample cells.
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The gratings are used over the frequency range νmin to νmax. νmin and νmax are the frequencies at which the intensity of radiation diffracted in the first order is approximately 50% of the peak intensity at the grating blaze.
Mirror M1 is covered with a layer of soot from a plumber's candle.
Chopper blades consist of 5-mm thick crystals of the salts shown.
Filters TG-i are polyethylene transmission gratings ruled on both sides with grooves orthogonal and with i lines/mm.
If the Golay cell is used a quartz filter is mounted on F1. With the bolometer the quartz bolometer windows act as filters.
The filters mounted on F2 are Yoshinaga-type filters containing the crystals indicated.
Either mirror M1 is covered with a layer of soot, or a 6-mil thick piece of black polyethylene is taped across the detector window
Chopper blades for the 140–450 cm−1 region consist of 5-mm thick crystals of the salts shown. For lower frequencies an aluminum chopper is used.
Filter mounts R1 and R2 hold reflection filters. R-i is a reststrahlen crystal of salt i while Z-i is a grating with i lines/mm used in zero order.
Filters TG-i are polyethylene transmission gratings ruled on both sides with grooves orthogonal and with i lines/mm.
A quartz plate is used with the Golay cell; the filter is left blank with the bolometer.
A coarser transmission grating is desirable for this region.
The gratings are used over the frequency range νmin to νmax. νmin and νmax are the frequencies at which the intensity of radiation diffracted in the first order is approximately 50% of the peak intensity at the grating blaze.
Mirror M1 is covered with a layer of soot from a plumber's candle.
Chopper blades consist of 5-mm thick crystals of the salts shown.
Filters TG-i are polyethylene transmission gratings ruled on both sides with grooves orthogonal and with i lines/mm.
If the Golay cell is used a quartz filter is mounted on F1. With the bolometer the quartz bolometer windows act as filters.
The filters mounted on F2 are Yoshinaga-type filters containing the crystals indicated.
Either mirror M1 is covered with a layer of soot, or a 6-mil thick piece of black polyethylene is taped across the detector window
Chopper blades for the 140–450 cm−1 region consist of 5-mm thick crystals of the salts shown. For lower frequencies an aluminum chopper is used.
Filter mounts R1 and R2 hold reflection filters. R-i is a reststrahlen crystal of salt i while Z-i is a grating with i lines/mm used in zero order.
Filters TG-i are polyethylene transmission gratings ruled on both sides with grooves orthogonal and with i lines/mm.
A quartz plate is used with the Golay cell; the filter is left blank with the bolometer.
A coarser transmission grating is desirable for this region.