M74050
1/4M IMAGING SPECTROGRAPHS
32
10 COMMUNICATION METHODS
In order to satisfy the needs of as many users as possible, the MS260i is designed to be controlled from a
variety of sources.
The MS260i is capable of automatically controlling an optional filter wheel, Models USFW-100 or 74010 . It
is also able to interface with the motorized filter wheel included with Oriel’s APEX2 light sources. These
filter wheels hold up to six 1-inch [25.4 mm] diameter filters. Neutral density filters can be used for intensity
adjustment. Order sorting filters may be installed to block higher order diffraction.
The filter wheel may be mounted to the male flange of the spectrograph slit or slit holder. The filters are
mounted external to the spectrograph. Thus, the refractive index and thickness of the filters do not
significantly affect the focal distance to the collimating mirror inside the spectrograph. With internal filters,
this distance would be different for every wavelength and every filter, and would therefore adversely affect
resolution. The MS260i is designed and manufactured to have errors of only a fraction of a millimeter in the
focal distance. Positioning the filters externally, usually before the input slit, has only a slight effect on the
light throughput. Since the slit acts as a secondary source, the focal distance is not affected.
Figure 23: Model 74010 Filter Wheel