OSU College of Arts and Sciences Department of Astronomy

MODS Gratings & Prisms

This document provides information on the MODS spectroscopic dispersers. At present we have two dispersers, a low-resolution reflection grating and a double-pass prism, in each channel, with a provision for a future third disperser with properties to be determined (but no money, so don't start making plans).

Contents

MODS1 Disperser Table
General Properties

MODS1 Dispersers

This table summarized the current Dispersers mounted in MODS1. The MODS2 gratings and prisms are replicas of these and will have the same basic properties.

Type ID Lines
(mm-1)		 Blaze
Angle		 Order Center
Lambda
(nm)		 Useful Range
(nm)		 0.6" slit
(pixels)		 Resolution
(0.6" slit)
Grating Red G670L 250 4.3° 1 800 550-1050 3.90 2300
  Blue G400L 400 4.4° 1 400 320-600 4.25 1850
Prism Red P700L n/a n/a n/a 800 550-1050 4.0 500-200
  Blue P450L n/a n/a n/a 450 320-600 4.0 600-150

Details:

MODS1 G670L Grating:
Catalog Number:53999ZD01-271R
Serial Number:MR122-5-5-1
Lines*:250 grooves/mm
Order:1st
Blaze Angle*:4.3°
Ruled Area:306x408mm
Resolving Power:2300 (4pix) at 760nm
Est'd Useful Range:500 to 1050nm
Angle of incidence:19.5°
Anamorphic Factor:1.04
Blaze Curve:[ Small GIF (5k) | Big GIF (52k) | Data ]
Surface Figure @ 632.8nm*:0.07 waves of power
0.25 waves P-V @ 100%
0.033 waves rms
Delivered:December 2005

MODS1 G400L Grating:
Catalog Number:53999ZD01-584R
Serial Number:MR162-2-7-1
Lines*:400 grooves/mm
Order:1st
Blaze Angle*:4.4°
Ruled Area:306x408mm
Resolving Power:1850 (4pix) at 408nm
Est'd Useful Range:320 to 600nm
Angle of incidence:19.76°
Anamorphic Factor:1.04
Blaze Curve:[ Small GIF (5k) | Big GIF (52k) | Data ]
Surface Figure @ 632.8nm*:0.27 waves of power
0.198 waves P-V @ 100%
0.023 waves rms
Delivered:December 2005

General Properties

Gratings

Vendor:Newport Richardson Gratings
Grating Type:Ruled Plano Reflection Grating
Format:Rectangular
Size:420x320mm
Thickness:50mm
Mass:12kg
Ruled Area:408x306mm
Ruling:Resin Replica
Substrate:Zerodur (Schott)
Coating:Aluminum
Special:20mm hole borded through center

Prisms

Vendor: JML Optical Industries, Inc
Prism Type:Double-Pass with Immersed Reflective Coating
Format:Oval
Size:240x220mm
Angle:30°
Mass:10kg
Material: Blue: Fused Silica
Red: TIH6
Coating: Blue: Aluminum
Red: Protected Silver
Special: 20mm hole borded through center
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Updated: 2011 May 3 [rwp]