The spectrophotometric colour analyser comprises an integral sphere with light source which irradiates both a test sample and a reference or control sample via apertures in the sphere. The respective emergent rays are focussed onto the inlet apertures of a twin spectrophotometer. Concave mirrors direct the beams onto diffraction screens. The split-spectrum beams are then directed onto the photo-cathode of an image analysing picture tube-electron multiplier. A computer controls the drive to a focussing and deflection system using magnet coils placed around the tube. The anode current is also controlled. By controlling the magnetic fields, the wavelength range of the part of the spectrum of interest can be selected. The intensities of the test and reference channels can be compared and evaluated by the computer.
Spectrophotometric colour analyser - uses single light source and computer-controlled photomultiplier for spectrum analysis