Abstract: A spherical sample cell (FIG. 4A) bears an external inwardly specular laye defining a hollow imaging mirror 11D and an optical aperture 11E. The mirror acts as an integrator of both the exciting radiation for irradiating the sample and the resulting excited radiation to be analysed, the former entering and the latter exiting through the aperture 11E. Optical integration resulting from multiple internal reflections provides multifold increase in excited radiation compared with bare cells, which is of particular advantage in Raman spectrophotometry. Alternatively, the mirror may be provided in two complementary halves in a two-part cell-holder, in which case any conventional sample cell that fits within the mirror may be used. Spectrophotometers adapted for use with the sample cell or the cell holder as well as methods based on them are described.

Abstract: A spectrophotometric system includes an optical device for providing an optical path from a radiation generating means to a radiation receiving means. The optical device includes a substantially opaque layer which defines first and second coplanar face regions having different optical functions.

Abstract: In spectrophotometric apparatus in which there are a plurality of operating parameters a system for selecting predetermined combinations of operating parameters is provided, having as many user operable main mode selection stations as there are main modes in the design range of the system and having a mode multiplying system which is adapted to modify, in response to the operative state of user operable control means, each main mode selected out of at least some of the main modes in the range, for converting the selected main mode into an auxiliary mode.