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Theory Of Operation Teledyne API M100E Analyzer Operation Manual
222
11.2. THE UV LIGHT PATH
The optical design of the M100E’s sample chamber optimizes the fluorescent reaction between SO
2
and UV
Light (refer to Figure 11-2) and assure that only UV light resulting from the decay of SO
2
* into SO
2
is sensed by
the instruments fluorescence detector.
UV radiation is generated by a lamp specifically designed to produce a maximum amount of light of the
wavelength needed to excite SO
2
into SO
2
* (214 nm) and a special reference detector circuit constantly
measures lamp intensity (refer to (Equation 11-2)). A Photo Multiplier Tube (PMT) dete
cts the UV given off by
the SO
2
* decay (330 nm) and outputs an analog signal. Several focusing lenses and optical filters ensure that
both detectors are exposed to an optimum amount of only the right wavelengths of UV. To further assure that the
PMT only detects light given off by decaying SO
2
* the pathway of the excitation UV and field of view of the PMT
are perpendicular to each other and the inside surfaces of the sample chamber are coated with a layer of black
Teflon
®
that absorbs stray light.
Figure 11-2: UV Light Path
04515F DCN6048