Optical Filters; Uv Source Optical Filter; Pmt Optical Filter; Figure 10-4. Excitation Lamp Uv Spectrum Before/After Filtration - Teledyne T101 Operation Manual

Teledyne ML - T101 Operation Manual

10.2.4. OPTICAL FILTERS

10.2.4.1. UV Source Optical Filter

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Figure 10-4. Excitation Lamp UV Spectrum Before/After Filtration

10.2.4.2. PMT Optical Filter

The Model T101 analyzer uses two stages of optical filters to enhance performance. The
first stage conditions the UV light used to excite the SO
light that are not needed to produce SO
from reacting to light not produced by the SO
Zinc-vapor lamps output light at other wavelengths beside the 214nm required for the
 SO
SO * transformation including a relatively bright light of the same wavelength
2 2
at which SO * fluoresces as it returns to its SO
2
intensity of the light emitted by the UV lamp at 330nm is so bright, nearly five orders of
magnitude brighter than that resulting from the SO
SO * fluorescence.
2
BEFORE
SO *
2
Fluorescent
Spectrum
300 400
WAVELENGTH (nm)
To solve this problem, the light emitted by the excitation UV lamp passes through a
bandpass filter that screens out photons with wavelengths outside the spectrum required
to excite SO into SO * (Figure 10-4).
2 2
The PMT used in the Model T101 reacts to a wide spectrum of light which includes
much of the visible spectrum and most of the UV spectrum. Even though the 214 nm
light used to excite the SO
direction of the PMT as it interacts with the sample gas. A second optical bandpass filter
placed between the sample chamber (see Figure 10-2) and the PMT strips away light
outside of the fluorescence spectrum of decaying SO
reflected UV form the source lamp and other stray light.
*. The second stage protects the PMT detector
2
* returning to its ground state.
2
UV SOURCE OPTICAL FILTER
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is focused away from the PMT, some of it scatters in the
2
Principles Of Operation
by removing frequencies of
2
ground state (330 nm). In fact, the
2
* decay, it would drown out the
2
AFTER
BANDWIDTH
SO * FLUORESCENT
2
SPECTRUM
200 300 400
WAVELENGTH (nm)
* (see Figure 10-5) including
2
500
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