Ametek Western Research IPS-4, User Manual

Page: 22 / 238

1-4 | IPS-4 Dual Bench (UV / IR) Analyzer
Dispersive Ultraviolet/Visible (DUVV) Spectrometer
Basic Analytical Theory
The DUVV Optical Bench measures transmittance, T
( )
λ
l
, over one or
more bands of wavelength,
( )
λ
l
. Transmittance is the ratio of the transmitted
power (originating from the source), I
( )
λ
l
, to the incident power, I
0
( )
λ
l
for
each wavelength (see Equation 1.1)
The DUVV Optical Bench operates in the near ultraviolet (200 to 400 nm)
and visible (400 to 800 nm) wavelength ranges of the electromagnetic
spectrum.
Optical Bench Design
An Optical Bench is composed of four main components:
• A source EM radiation (or “light”) in the wavelength region of interest.
• Measuring Cell with windows capable of transmitting light in the
region of interest and compatible with the sample composition.
• A wavelength selection device to isolate wavelengths of interest for a
specific application.
• A detector (or sensor) that is sensitive to the wavelength region.
The combination of the wavelength selection device and detector is
also referred to as a spectrograph. Figure 1-2 illustrates the complete
optical path from source to detector for the DUVV and Optical Bench.
Figure 1-2.
Analyzer light path,
UV schematic.

NOTE