Specifications

Chapter 3 First Light 31
has been properly installed. See your detector and spectrograph manual for mounting
instructions. A suitable light source, such as a mercury pen-ray lamp, should be mounted in
front of the entrance slit of the spectrograph. Any light source with line output can be used.
Standard fluorescent overhead lamps have good calibration lines as well. If there are no
“line” sources available, it is possible to use a broadband source such as tungsten for the
alignment. If this is the case, use a wavelength setting of 0.0 nm for alignment purposes.
Note: If you purchased an optical-fiber adapter and cable, install them only after the
regular alignment procedure has been successfully completed. Consult the Optical Fiber
Adapter manual for specific instructions.
In a typical spectrograph, light enters the entrance slit and is collected by a collimating mirror.
Collimated light strikes the grating and is dispersed into individual wavelengths (colors). Each
wavelength leaves the grating at a different angle and is reimaged by a focusing mirror onto
the intensifier photocathode at the exit focal plane. Essentially, what a spectrograph does is to
form an image of the entrance slit in the exit focal plane with each position in the plane
representing a different wavelength. As each wavelength images at a different horizontal
position, the spectrum of the input light is spread across the CCD. Individual wavelengths
focused at different horizontal positions along the exit port of the spectrograph are detected
simultaneously. Rotating the diffraction grating scans wavelengths across the CCD, allowing
the intensity at individual wavelengths to be readily measured.
Spectroscopy Procedure
If the system cables haven’t as yet been installed, connect them as follows (system power off).
• Connect the 25-pin cable from the DETECTOR connector on the
Analog/Control module panel to the mating connector at the camera. Be sure to
secure the cable at both ends.
• Connect one end of the 9-pin serial cable to the SERIAL COM connector on the
Interface Control module panel. Connect the other end to the computer interface
as described in Appendix I. Be sure to secure both ends of the cable.
• Connect the line cord from the Power Input assembly on the back of the
controller to a suitable source of AC power.
Coolant
Circulator
Computer
110/220
Shutter
TAXI cable
(Serial Com)
Controller
SerialDetector
EXPERIMENT
110/220
Inlet
Outlet
110/220
Detector
Detector-Controller
Spectrometer
Figure 9. System connection diagram, TE camera