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Build the largest telescope you can!
refractors reflectors doubling time ~ 50 yr
ASTR633 Astrophysical Techniques Course slides Chapter 2: - - PowerPoint PPT Presentation
ASTR633 Astrophysical Techniques Course slides Chapter 2: - - PowerPoint PPT Presentation
ASTR633 Astrophysical Techniques Course slides Chapter 2: Telescopes Build the largest telescope you can! reflectors refractors doubling time ~ 50 yr Huygens-Fresnel principle Huygens-Fresnel principle wikipedia! Airy Function k = 2 /
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Huygens-Fresnel principle
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Huygens-Fresnel principle
wikipedia!
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Airy Function
k = 2π/λ
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Reflectors vs Refractors
Refractors have wavelength-dependent focus (chromatic aberration). Reflectors do not. Refractors need bubble-free volumes. Reflectors only need bubble-free surfaces. Refractors must be supported at the edge ! weakest point. Reflectors can be supported over the entire back. Refractors require large tubes. Reflectors allow for more compact designs.
! All OIR scientific telescopes are reflectors.
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Newtonian
wikipedia!
No correction for curved primary => aberrations
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Cassegrain
wikipedia!
Ritchey-Chretien has a hyperbolic (not parabolic) primary
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Gregorian
wikipedia!
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UH 2.2m Equatorial Mount and Coudé Focus
88-inch Reflector
- El. 13,824
Observing Platform
Control Room
Coudé Room Aluminizing Tank
Figure 6.3: Layout of the 2.2-m telescope dome
http://www.ifa.hawaii.edu/88inch/manuals/user.pdf
coudé = elbow
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CFHT —> MSE?
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Subaru Alt-Az Mount and Nasymth Focus
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Arecibo Spherical Reflector
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Two mirror system
plate scale = θ/y ≈ (y/f)/y = 1/f
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IRTF Secondary Mirror
f/38
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Pan-STARRS Secondary Mirror
f/4.4
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LSST Optical Design
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LSST Optical Design
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Gemini IR Optimized Telescope
http://www.gemini.edu/project/announcements/press/2004-12.html
50g Ag
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GBT = Green Bank Telescope (aka Great Big Thing)
100m f/0.6, λ = 3mm - 30cm Largest steerable structure in the world Off-axis paraboloid Active surface
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Inteferometry —> structural rigidity on long baselines
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