Thermo Scientific 074114, Руководство оператора

Страница: 23 / 148

2 • Description
Doc. 065378-01 1/12
15
Optical System
Component Function
Tungsten Lamp The light source for visible and near-infrared wavelengths (380 to
800 nm). The tungsten lamp is focused through an opening in the
internal structure of the deuterium lamp; this allows the lamps to
share the optical axis to the source lens.
Visible Focus Lens Focuses the visible light from the tungsten lamp to the through-
hole of the deuterium lamp.
Deuterium Lamp The light source for UV wavelengths (190 to 380 nm).
Source Lens Receives the light from the tungsten and deuterium lamps and
focuses it so that the beam passes through the flow cell.
Flow Cell The measurement site for sample absorbance. The cell has a flat
window on each side. Thermo Fisher Scientific offers five cells
for use with the Dionex PDA: standard cells (in both PEEK and
316 stainless steel), semi-micro cells (in both PEEK and 316
stainless steel), and semi-preparative cells (in PEEK only).
Spectrograph Lens Receives the light from the flow cell and focuses it onto the slit.
Filter Paddle The motorized filter paddle in the spectrograph has three
positions:
•
Open = Light passes, unobstructed, along the light path when
the holmium oxide filter is moved out of the light path.
•
Blocked = No light passes along the light path; used to
measure the dark signal without turning off the lamps.
•
Holmium = Places the holmium oxide filter in the light path;
used to verify wavelength accuracy.
Slit The width of the slit (equivalent to 1 nm) optimizes the optical
resolution.
Grating Diffracts the light beam into its component wavelengths and
directs the light onto the photodiode array.
Photodiode Array A series of 1024 photosensitive elements. Each element measures
a narrow band of the spectrum. A spectrum is obtained by
measuring the light intensity of each wavelength and reporting the
results over the selected wavelength range.