Herriott-Type Cell ST

An incident beam enters the cell through the input / output aperture. The beam then undergoes 73 reflections between two gold-coated spherical mirrors, describing a circle of spots on the surface of the mirrors before exiting the cell through the input / output aperture. The dimensions of the mirrors, seperation between adjacents spots, and the diameter of the input / output aperture have been designed to avoid spot overlap and thus unwanted interference up to wavelengths of 3µm.

The input and output beams travel on different planes. This ensures clear seperation between the input and output beams, permitting accurate absorption measurements even in the case of misalignment or incorrect focusing. The cell is resistant to most common chemicals. The materials in contact with the gas are; Pyrex and BK7 Glass, Stainless Steel, CaF2, Gold, Viton, and Teflon. The cell can be operated at pressures from 10-3 Torr up to 1 atm. Gas inlet and outlet ports at either end of the cell allow for examination of flowing gases. Alternativeley the Pyrex tube can be removed in-situ without dismantling the cell, when 'room air' measurements are to be performed.

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Herriott-Type Cell ST


Herriott-type multipass absorption cell. Price upon request.


Price on Application

Fact File


Optical Path Length:29.9m
Volume:900 cm3
Overall length:50.2 cm
Overall width:13.7 cm
Overall height:9.4 cm
Mirror reflectivity (λ>1µm)>98.2%
Transmission (window excluded,  λ>1µm)>26.6%.

Maximum wavelength:
(To avoid interference between
 reflection spots)

Operating pressure:10-3 to 760 Torr
Window transmission (CaF2)0.2 µm to 9.5 µm