NIR LOWFS for Keck and TMT Roger Smith & David Hale.
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Transcript of NIR LOWFS for Keck and TMT Roger Smith & David Hale.
![Page 1: NIR LOWFS for Keck and TMT Roger Smith & David Hale.](https://reader036.fdocuments.net/reader036/viewer/2022062313/56649d3e5503460f94a172fe/html5/thumbnails/1.jpg)
NIR LOWFS for Keck and TMT
Roger Smith & David Hale
![Page 2: NIR LOWFS for Keck and TMT Roger Smith & David Hale.](https://reader036.fdocuments.net/reader036/viewer/2022062313/56649d3e5503460f94a172fe/html5/thumbnails/2.jpg)
ComparisonKeck IR TT TMT IRIS OIWFS
Detector 2.5 µm H2RG 2.5 µm H2RG Subarray, Low noise
Acquisition FoV 1200 x 1200 1000 x 1000 pixels
Plate scale 0.100 0.002 arcsec/pixel
Acquisition FoV 120 ~5 arcsec
Passband K J+H
Optics Full field, reimager with cold Lyot stop
3 probe arms with 2x2 lenslet inserted on brightest star.
Output frame rate (minimum)
1000 80 Hz
# windows,size
1 to few. 2x2 to 4x4
1 or 4,4x4 nested in 14x14?
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Topics• Thermo-mechanical– For Keck: proposal (optical layout, dewar layout)– For TMT: eDrawing
• Detectors considered• H2RG read mode• Resulting noise vs frame size (or rate)– For TMT– For Keck
• TMT sky coverage• Bad pixels: noisy, hot or insensitive
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Keck 1 Layout
LGS AO control schematic with the new NIR TTS system added (upper right). A fold located just in front of the science camera reflects light to the NIR TTS assembly mounted on a focus stage. The TTS output is processed to provide TT control of the Tip-Tilt Mirror (TTM) as an alternative to the existing visible TTS (STRAP) or in combination. Focus information, if available, could be used to control the wavefront sensor (WFS) focus.
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Keck 1 Pickoff Options
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Keck 1 reimaging dewar
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TMT: 3 R-theta probes
1 of 3 sensor dewars
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Sensor Dewar
Focal planeGetter on cold head
Cryotiger, decoupled from detector
Cold filter location
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Preliminary Cooling Curve
Masses and surface areas are guesses, to be updated from solid model !
Ample power margin; safe cooling rate.
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Keck 1 noise vs frame rate