Princeton Instruments NIRvana-LN, User Manual, Page: 34 / 122

34 NIRvana
™
-LN System Manual Issue 4
4.6.2 Optical Center of the Array
An LN-cooled detector shrinks when the Dewar is filled with liquid nitrogen, and the
detector cools down to operating temperature. For side-on Dewars, the optical center of the
array shifts downward by 0.022” [0.559 mm] and toward the mounting face by 0.010”
[0.254 mm]. Because of this, an image area or a focus set at room temperature will change
as a detector cools.
The NIRvana-LN is designed so the optical center of an array is offset at room temperature.
Now, when a detector cools to operating temperature, the optical center of the array is at the
center of the nose.
4.6.3 Array Orientation
All users with rectangular arrays must first determine the correct orientation of the detector.
All detectors must be mounted in the correct orientation to take advantage of the many
hardware and software features. The detector should be mounted so that the short axis of the
array is parallel to the entrance slit. The long axis will therefore correspond to the
wavelength axis of the spectrum, for maximum resolution.
The simplest way to determine the long and short axes of an array is to make a visual
inspection of the faceplate. The faceplate cutout closely corresponds to the dimensions of
the underlying array, which will itself be visible through the window.
4.7 Using an External Shutter
NIRvana-LN detectors do not contain internal shutters. However, a Princeton Instruments
25 mm external shutter, which is typically placed over the entrance slit of a spectrograph,
can be purchased.
Perform the following procedure to install a
Princeton Instruments-supplied 25 mm External
Shutter onto a spectrometer:
1.
Verify that the detector’s power supply is
OFF.
2.
Bolt the entrance slit shutter assembly to the
entrance slit of the spectrograph. The entrance
slit shutter mount used with Acton SpetraPro
series spectrographs requires no disassembly.
See
Figure 4-3 .
3.
Connect the shutter cable to the
Shutter
connector on the back of the NIRvana-LN’s
electronics box.
Adapter
Spectrometer
Figure 4-3: Entrance Slit Shutter
Mount
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