| SOLUTION |
The
solution required a number of stages because of the
extremely low level of the excited fluorescence, which
was not made clear at the outset.
The light source: A Xenon flash lamp, was tried but
rejected because of high electrical noise, a high
intensity mercury lamp gave excellent results.
The detector: As the amount of light excited was so
small a photomultiplier had to be used, both standard
and avalanche photodiodes proved insufficiently sensitive.
The optics: Given the constraints of the small space
available and the necessity of focussing on a 1mm
cross section flow cell, a system of concave mirrors
was designed. The resulting system gave good signal
levels on the full range of chemical samples. |
| TECHNOLOGIES
REQUIRED |
Photodetectors,
Optics, Mechanical Engineering, Light Sources, Electronics. |
