Specifications for visitor filters for the LRS

Gary J. Hill, April 2002

Several positions are available for visitor or custom filters to be used in the LRS on a temporary basis. Filters can be used for imaging or as blocking filters for spectroscopy. Spare filter holders are available, which will accommodate circular filters with the following characteristics:

  • Diameter: 100 (+0.0/-0.3) mm
  • Thickness: 8 mm
  • Flatness: 1 wave per inch or better, 1 arcminute maximum wedge
  • Clear aperture 85% (85 mm)
The thickness cannot be less than 5 mm or more than 10 mm. Thinner filters will not allow the instrument to focus, and thicker are not accommodated by the holders. If there is demand, we can create holders that will accept 4.0 inch diameter circular filters, but we will need 6-8 weeks notice.

In order to use a custom filter in the LRS, it must be mounted in a spare position, and the focus offset for the filter must be determined. It should have a unique and not overly long name, to identify it in the ICE software. Spaces are not allowed in the identifying name.

If custom filters are being ordered from a manufacturer, we recommend the following specifications in addition to the bandpass and size:

  • blocked less than 10^-3 from 0.35 to 1.2 microns
  • hard AR coating
  • no visible pinholes (for use with CCD detector)
    • this is for interference filters
  • will be used at 10 Celsius, normal incidence in f/5 beam
  • sealed on the edge with no light leaks and marked with the name
  • transmission curves to be supplied
Specific questions can be directed to Gary Hill at: hill@astro.as.utexas.edu

Last updated: Sun, 08 Jan 2012 02:08:00 -0600 caldwell


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