1 Optics •Design Overview –Overview –Performance •Coude Feed •Gregorian •Prime Focus •Primary Mirror Overview •Secondary Mirror Overview Jim Oschmann Ron Price Optical Design Overview • Primary Mirror – 4 meter clear aperture, off axis (12 meter parent) – F/2 • Heat stop at prime focus – Allows 3-5 arc minutes through system – Potential occulting disk area • Secondary Mirror – 600 mm off axis gregorian – Gregorian focus at f/13 • Feed Optics – Relay image to Coude area – F/69 (over elevation & azimuth axis) – Contains Deformable and tip/tilt mirrors for AO – Further interface optics for specific instruments needed
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Optics Overview d - Welcome to the DKIST | DKIST · 2020. 1. 22. · Optics •Design Overview –Overview –Performance •Coude Feed •Gregorian •Prime Focus •Primary Mirror
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• Primary Mirror– 4 meter clear aperture, off axis (12 meter parent)– F/2
• Heat stop at prime focus– Allows 3-5 arc minutes through system– Potential occulting disk area
• Secondary Mirror– 600 mm off axis gregorian– Gregorian focus at f/13
• Feed Optics– Relay image to Coude area– F/69 (over elevation & azimuth axis)– Contains Deformable and tip/tilt mirrors for AO– Further interface optics for specific instruments needed
2
M2
M4
DM
M3
M3
M4
M2
M1
Coude Focus
3
Coude Focus
0.1”
Gregorian Focus
4
Gregorian Focus
0.2”
Prime Focus
5
Prime Focus
13 arc sec
Primary Mirror Overview
• Blank Configuration• Blank Material• Polishing• Support System• Procurement Schedule
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Preliminary Mirror Blank Configuration
Ø12100 PARENT PARABOLOID
4000
(4100)
100
ALL DIMENSIONS IN MM.
Ø4237
SURFACE A
SURFACE B
ATST PRIMARY MIRROR
PARENT PARABOLOID
GEOMETRICAL AXIS OF ATST PRIMARY MIRROR BLANK
AXIS A,GEOMETRICAL AXIS OF
PARENT PARABOLOID
A
SECTION A-A
Mirror Blank Material
• Selection of mirror blank material is driven by large temperature gradients from front to back
• Ultra-low-expansion material is needed to maintain optical figure under these conditions