Hitachi U-5100 Instruction Manual page 324

APPENDIX
Appendix a. Operating Principles of Model U-5100
Optics:
Figure "a" shows the optics of Model U-5100 ratio beam
spectrophotometer. For radiation source, a xenon flash lamp
is used. The white light emitted from the radiation source
passes through the filter and entrance slit and is converted
into a monochromatic beam by the Seya-Namioka mount
monochromator. This monochromator uses a Hitachi's
original stigmatic concave diffraction grating with a grating
constant of 1/600 nm, blaze wavelength of 250 nm and
diffraction area of 20 mm by 25 mm. The monochromatic
beam is restricted into a bandpass of 5 nm with the exit slit,
reflected by the toroidal mirror (M2) and split into a monitor-
side (reference) beam and a sample beam. The monitor-side
beam is incident on the monitor-side detector mounted in the
monochromator. The sample beam passes through a
sample in the sample compartment and impinges upon the
sample-side detector.
The sample and reference beams incident on the respective
detectors are converted into electric signals. The Model U-
5100 detects the reference beam in order to compensate for
variations in light quantity with time. This optics is called
"ratio beam." The ratio beam spectroscopy ensures a highly
stable photometric values unavailable with a single beam
spectrophotometer.
The beam at the center of a set 10 mm rectangular cell is 9
mm high and 3 mm wide.
APPENDIX - 1