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ATST Imager and Slit Viewer Optics
Ming Liang
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Optical layout of the telescope, relay optics, beam reducer and imager.
Optical Layouts
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Gregorian Position
Gregorian Instrument Bench
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Spot diagrams on the Gregorian focus
Spot Diagrams
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Design property Requirement
Field of view 3’ x 3’ for f/20 imager
1.5’ x 1.5’ for f/40 imager
Wavelength band 0.33 to 1.1 μm
Image quality Within the diffracted limitation
Focal surface Flat focal surface and telecentric output
Visible Imager Design Requirements
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FOV: 3’ x 3’. Wavelength band:0.33 to 1.1 μ.
Flat focal surface and telecentric output.
The total bulk absorption is about 7% at 330 nm wavelength band
N-BaK2 CaF2 N-BaK2 N-BaK2 CaF2 Silica
F/20 Visible Imager
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Spot diagrams for f/20 imager, within 3’x3’ fields. The circles in the spot diagrams are Airy disk size at 630 nm wavelength.
Up left: Normal position.
Up: 45º altitude.
Left: 45º azimuth.
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FOV: 3’X3’, wavelength band: 0.33 to 1.1 μm, slit mirror tilt 22.5°
Slit mirror
Slit viewer optics
F/20 imager
F/20 Visible Imager and Slit Viewer Optics
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Spot diagrams for f/20 slit viewer, within 3’x3’ fields. The circles in the spot diagrams are Airy disk size at 630 nm wavelength
Up left: Normal position.
Up: 45º altitude.
Left: 45º azimuth.
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N-BaK2 CaF2 N-BaK2 CaF2 N-BaK2 Silica
FOV: 1.5’ x 1.5’. Wavelength band:0.33 to 1.1 μ.
Flat focal surface and telecentral output
Con-focus with that of f/20 imager
F/40 Visible Imager
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Spot diagrams on f/40 Imager focus within 1.5’x1.5’ fields. The circles in the spot diagrams are Airy disk size at 630 nm wavelength
Up left: Normal position.
Up: 45º altitude.
Left: 45º azimuth.
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FOV: 1.5’x1.5’, wavelength band: 0.33 to 1.1 μm, flat focus.
The same guiding system works for both f/20 and f/40 imager.
F/40 imager
Slit viewer optics
F/40 Visible Imager, Slit Mirror and Slit Viewer Optics
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Spot diagrams for f/40 guider, within 1.5’x1.5’ fields. The circles in the spot diagrams are Airy disk size at 630 nm wavelength
Up left: Normal position.
Up: 45º altitude.
Left: 45º azimuth.
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Design property Requirement
Field of view 3’ x 3’ for f/20 imager
1.5’ x 1.5’ for f/40 imager
Wavelength band 1 to 5 μm
Image quality Within the diffracted limitation
Focal surface Flat focal surface and telecentric output
IR Imager Design Requirements
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FOV: 3’ x 3’. Wavelength band:1 to 5 μ., Flat focal surface and telecentric output.Lens materials (follow the light pass): ZnSe, BaF2, CaF2 and CaF2.
F/20 IR Lens Imager
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Spot diagrams of f/20 lens imager for wavelength from 1 to 5 μm. The circles in the spot diagrams are Airy disk size at 1.6 μm wavelength.
Spot Diagrams
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FOV: 1.5’ x 1.5’. Wavelength band:1 to 5 μ., Flat focal surface and telecentral output.To make it con-focus with f/20 imager, there are two more lenses than the f/20 IR lens imager. Lens materials (follow the light pass): ZnSe, BaF2, CaF2, ZnSe, BaF2 and CaF2.
F/40 IR lens imager
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Spot diagrams of f/40 IR lens imager. The circles in the spot diagrams are Airy disk size at 1.6 μm wavelength.
Spot Diagrams
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Reflected Imager Options(For visible and IR)
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Design property Requirement
Field of view 3’ x 3’ for f/20 imager
1.5’ x 1.5’ for f/40 imager
Wavelength band 0.33 to 28 μm
Image quality Within the diffracted limitation
Focal surface Flat focal surface and telecentric output
Optical Design Requirements
212 mirror F/20 imager with flat focal surface and telecentric output.
F/20 Reflected Imager
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Spot diagrams for f/20 Imager, within 3’x3’ fields. The circles in the spot diagrams are Airy disk size at 630 nm wavelength
Up left: Normal position.
Up: 45º altitude.
Left: 45º azimuth.
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Folding mirror
F/40 Reflected Imager
Optical layout of f/40 visible imager with flat focus and telecentral output FOV: 1.5’x1.5’, wavelength band: 0.33 to 1.1 μm.
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Spot diagrams on f/40 Imager focus within 1.5’ x 1.5’ field. The circles in the spot diagrams are Airy disk size at 630 nm wavelength
Up left: Normal position.
Up: 45º altitude.
Left: 45º azimuth.
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F/40 Imager
F/40 Imager folding mirrors
F/20 Imager
The drawing shows how to exchange the f/20 imager to f/40 imager. When the f/40 imager is inserted, the f/20 beam will be bypassed by the f/40 folding mirror to the detector.
Imager Exchange
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IR channel
Visible channel
Dichroic
Lens imagers in visible channel and mirror imagers in IR channel
System Arrangement
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Optical Train From Telescope to DetectorATST 250 K Visible Spectrograph
Example(Current Spectrograph to be presented by David Elmore
or HAO and Don Mickey for IR version)
Telescope – Collimator Relay – Beam Reducer – f/20 Imager – CT spectrograph
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F/20 imager
Spectrograph
F/20 Imager and Spectrograph
29The optical layout shows the whole system from telescope to spectrograph.
Whole Optical Layout
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Multiple Instrument Example
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Multiple Instrument Example
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Multiple Instrument Example