PerkinElmer Lambda 1050, Hardware Manual

Page: 28 / 82

28 . High-Performance Lambda Spectrometers Hardware Guide
For operation in the ultraviolet (UV) range, mirror M1 is raised to permit radiation from the
deuterium lamp to strike source mirror M2. Source change is automatic during
monochromator slewing.
Radiation from the respective source lamp is reflected from mirror M2 via mirror M3 through
an optical filter on the filter-wheel assembly (FW) to mirror M4.
The filter wheel is driven by a stepping motor to be in synchronization with the
monochromators. Depending on the wavelength being produced, the appropriate optical
filter is located in the beam path to prefilter the radiation before it enters the
monochromator. Filter change is automatic during monochromator slewing.
From mirror M4, the radiation is reflected through the entrance slit of Monochromator I. All
slits are located on the slit assembly (SA). The radiation is collimated at mirror M5 and
reflected to the grating table G1. Depending on the current wavelength range, the collimated
radiation beam strikes either the UV/Vis grating or the NIR grating.
NOTE: The NIR grating is not available in the Lambda 650 or 850 spectrometers.
The radiation is dispersed at the grating to produce a spectrum. The rotational position of
the grating effectively selects a segment of the spectrum, reflecting this segment to mirror
M5 and then through the exit slit. The exit slit restricts the spectrum segment to a near-
monochromatic radiation beam. Grating change is automatic during monochromator slewing.
The exit slit of Monochromator I serves as the entrance slit of Monochromator II. The
radiation is reflected via mirror M6 to the appropriate grating on grating table G2 and then
back via mirror M6 through the exit slit to Mirror M7. The rotational position of grating table
G2 is synchronized to that of grating table G1. The radiation emerging from the exit slit
exhibits high spectral purity with an extremely low stray radiation content.
In the UV/Vis and NIR range, a choice is provided between a fixed slit width, a servo slit, and
a slit program. When the servo slit is selected, the slit widths change automatically during
scanning to maintain constant energy at the detector.
From mirror M7, the radiation beam is reflected via toroid mirror M8 to the chopper assembly
(C). As the chopper rotates, a mirror segment, a window segment and two dark segments
are brought alternately into the radiation beam.
When a window segment enters the beam, radiation passes through to mirror M9 and is then
reflected via mirror M10 to create the reference beam (R).
When a mirror segment enters the beam, the radiation is reflected via mirror M10′ to form
the sample beam (S).
When a dark segment is in the beam path, no radiation reaches the detector, permitting the
detector to create the dark signal.