TRISPEC Grisms

The insrument has a grism wheel for each channel, and five grisms can be mounted on the each wheel. Currently, only one set of the low dispersion grisms are installed on the grism wheels. This set can almost cover the wavelength range of 0.46 to 2.5 µm simultaneously. The set of the grisms are orignally designed by N.Ebizuka. See also the web page by N.Ebizuka (Japanese). The specification and the measured efficirncy of these grisms are the below table and figures.


Specification of low disersion grisms

 
 
Optical
IR1
IR2
Dispersion grade
Low
Low
Medium
Coverage
0.46 - 0.90 µm
0.90 - 1.80 µm
1.90 - 2.50 µm
Resolving power (slit width: 300 µm)
138
142
360
Resolving power (slit width: 450 µm)
92
95
240
Resolving power (slit width: 600 µm)
69
71
180
Material
BK7
BK7
FTM16
Order
1st
1st
1st
Brazed wavelength
0.665 µm
1.30 µm
2.22 µm
Grooves
200 l/mm
120 l/mm
150 l/mm
Blaze angle
15.0 deg
17.45 deg
36.8 deg
Prism apex angle
15.0 deg
18.0 deg
36.8 deg


Efficiency of low dispersion grisms (at room temperature)


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Last Modification Date: 2001/02/18
Last Modification Author: Makoto Watanabe <watanabe@z.phys.nagoya-u.ac.jp>