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Date Announced: 10 Jan 2012
Photonics Technologies, Woking, UK. Specialist supplier of lasers and accessories for the atomic and molecular spectroscopist introduces Herriott type, multi-pass gas cells into their extensive range of components and instruments.
For atomic absorption spectroscopy to able to measure low concentrations of aerosols and molecules in a mixed gas it is necessary to increase absorbance by having a long path length through the sample. Herriott type cells multiply the effective path length through a gaseous medium and thereby increase absorbance. This improves an absorption spectrometer’s resolution and sensitivity but keeps the test instrument light and small.
Photonics Technologies’ Herriott type cells have a total optical path of 30m and are suited to infrared absorption spectroscopy and other applications which require a long interaction path with a gaseous sample. Applications include gas monitoring in the laboratory or industrial environments, for spectrometer manufacturers and end user researchers wishing to develop or build a near-infrared absorption spectroscopy system.
The design and materials used to construct these gas cells make them very compact and robust and this, combined with the stability of the optical configuration, makes them ideal for measurements in laboratory and field applications.
The Herriott cell is manufactured to ensure uncompromised performance. Within a glass cell, two spherical concave mirrors face each other and the incident laser beam enters the cell through a hole in one mirror then undergoes 73 reflections, describing a circle of spots on each mirror surface, before exiting through a hole in the second mirror. The beam enters the cell in the horizontal plane, whilst the output beam exits at a higher angle which ensures a clear separation between input and output beam, permitting accurate absorption measurements even in cases of incorrect alignment or poor focussing.
Two models of Herriott Type Cell are offered, CMP-30 and CMP-30 HP, the latter is strengthened for high pressure applications with the Pyrex tube of the CMP-30 standard being replaced by a steel tube. It also incorporates a high pressure release valve and can be used for applications up to 5 atm.
The cells are resistant to the most common chemicals. Materials in contact with the gas are Pyrex and BK7 glass, stainless steel, CaF2, Gold, Viton and Teflon. Gas inlet and outlet ports at both ends of the cell allow for examination of flowing gases. When ‘room air’ measurements are to be performed the Pyrex glass pipe can be removed in-situ without dismantling the cell.
E-mail: info@photonicstechnologies.com
Web Site: www.photonicstechnologies.com
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