JPS54123085A - Spectrophotometer - Google Patents

Abstract

PURPOSE:To give an optical system having little stray light to a photometer having vertically split slits by shifting been light incident upon a concave diffraction grating out of the direct incident point, while imparting fine rotations to the grating, so that the light of zero order is shifted from the slit. CONSTITUTION:The light from a lamp 1 is divided by a split lens 2 into two beams, which are guided through sample reference calls 3 and 4 and a holed slit 5 having vertically split portions into a photometer chamber. The respective beams are dispersed by a concave diffraction grating 6 and are reflected by a mirror 9 so that the absorptivity is metered by a detector 7. At this time, the grating 6 is slightly turned, as shown in arrow, to return the light of zero order onto the surface of the slit 5 thereby to eliminate the reflections at the end faces of the cells 3 and 4. The portion of the zero order light returned is further guided into an optical trap 8 to prevent the stary light due to the random reflections at the slit 5 so that a spectrophotometer having little stray light can be produced without deteriorating the brightness of the photometer.