WIYN Observatory

BENCH SPECTROGRAPH

The Bench Spectrograph is a stable, isolated spectrograph optimized for use with optical fibers. It permits relatively easy changes of configuration between high and low dispersion and between various spectral regions. Hydra, SparsePak, HexPak and GradPak all feed into the Bench Spectrograph.

The Bench Spectrograph was upgraded in 2008. The upgrade consisted of implementing a faster, all transmission collimator, the capability to use VPH transmission gratings over a full range of incidence angles, two VPH gratings, and a new CCD system. Together, these improvements have yielded gains in throughput of factors of 2-5 over the existing system while maintaining or improving spectral resolution and sampling for most applications, and at most degrading spectral resolution by 20%. More information on the upgrades can be found in the published SPIE papers: "The upgraded WIYN Bench Spectrograph", Knezek et. al and "WIYN bench upgrade: a revitalized spectrograph", Bershady et. al.

Available Bench Gratings

Grating l/mm Blaze Angle Peak Efficiency Ruling (mm) Notes
316 @ 7.0 316 7.0° 70% 259 x 213 Similar to BL181
400 @ 4.2 400 4.2° 70% 262 x 217 First Order Blue
600 @ 10.1 600 10.1° 72% 210 x 216 New Feb. 1999
600 @ 13.9 600 13.9° 70% 256 x 206 Similar to BL420
860 @ 30.9 860 30.9° 65% 262 x 217 Similar to KPC-24
1200 @ 28.7 1200 28.7° 55% 262 x 206 Similar to BL380
316 @ 63.4 316 63.4° 50% 206 x 406 Echelle grating
740 VPH 740 20°     Volume Phase Holographic
3300 VPH 3300 57°     Volume Phase Holographic

Sample Bench Configurations

Grating Central λ (Å) Order Lambda Coverage (Å)
BSC		 Spectral Resolution (Å)
Red Cable1 Blue Cable2
316 @ 7.0 7500 1 5290 5.72 8.87
316 @ 7.0 3750 2 2645 2.86 4.44
400 @ 4.2 5000 1 41993 4.56 7.07
600 @ 10.1 5500 1 2763 3.35 4.60
600 @ 13.9 7500 1 2724 2.86 4.43
600 @ 13.9 3800 2 1362 1.43 2.22
860 @ 30.9 10800 1 1680 1.64 2.54
860 @ 30.9 6000 2 840 0.77 1.19
860 @ 30.9 4000 3 560 0.52 0.80
1200 @ 28.7 7500 1 1231 1.19 1.84
1200 @ 28.7 4000 2 615 0.58 0.90
316 @ 63.4 6563 9 265 0.16 0.25
316 @ 63.4 3890 14 170 0.16 0.27
740 VPH 8798 1 2152 ?? ??
740 VPH 4399 2 1076 ?? ??
3300 VPH 5120 1 273 ?? ??

1Transmission of the red fibers drops off rapidly blueward of 4000(Å).
2Transmission of the blue fibers drops off non-uniformly redward of 8500(Å).
3Not recommended due to difficulty focusing over the wavelength range.

Last modified: 03-Apr-2020 16:10:21 MST