Gas Cells

Additional Information

• The pathlength is the how far the incident beam travels through the gas. These are often termed as short, long or variable pathlengths.
• A short pathlength is sufficient for high concentration mixtures, for example, a reference cell filled with 100% methane.
• A long pathlength would be needed if the concentration of the gases is lower and often given as parts-per-billion (ppb), this would be needed when, for example, the levels of greenhouses gases are being measured in an air sample.
• Knight Optical can supply fixed or variable pathlength gas cells, where variable types used mirrors to increase the pathlength by reflecting the beam throughout the cell rather than straight through.
• There are also cell types for holding vapours and liquids. For example, our drilled cell windows can be used in demountable cell holders, which generally hold liquid samples.

Quality Assurance

• The flatness and irregularity of the transmission windows are tested on our Zygo Verifire XPZ interferometer, where we can also test the transmitted wavefront error of the window.
• We check the parallelism on our Trioptics PrismMaster which is accurate to 3 arc seconds.
• Transmission and reflection scans are conducted on our Agilent Cary 7000 Spectrophotometer which can perform spectral scans at multiple angles of incidence and different polarisations.
• We can then further test the infrared transmission on our Agilent Cary 660 FTIR spectrometer.
• All optics are 100% visually inspected before packaging, our staff are trained to ISO 10110 and MIL-0-13830A, and can check down to 10/5 scratch/dig which is especially critical in laser applications.