Abstract: A method of collecting optical energy which allows the use of short focal length mirrors of relatively small physical size and in particular the use of the standard collecting mirrors usually employed in such spectrophotometers, for a wide range of sample sizes and collection configurations. A relatively large diameter internal surface, which in many cases can be incorporated into the design of other elements in the sampling system, is used. A physically large cell is interfaced to a radiation collector, such as a mirror. In this case the nut sealing the end window on the cell is internally coated (with gold in the preferred embodiment) to constitute a surface and this acts as a transfer mechanism for the backs-scattered radiation from sample. A solid collecting angle of 60 degrees (in this example) can be so obtained to transfer the energy to the standard radiation collector, such as a collecting mirror, of the spectrophotometer.

Abstract: A liquid cell for use in spectroscopic analysis of flowing liquids formed by a front plate (1) as an optical window, a back plate (2) providing a reflecting surface (6), and a sealing means (3) between the two plates. In the back plate there are entry part (4) and exit part (5) for liquids to the cell. This arrangement is convenient to connect for liquid through-put, and gives extra sensitivity and allows detection of very small quantities of material present in the flow.