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Telescopes - Coggle Diagram

- - - - fast -- small f/R
      - slow -- large f/R
  - - - Airy Disk: θmin = 1.22*λ/d
    - - PSF is often spread out in within ~4𝜎 in diameter
      - 1.7 × seeing (i.e. within ~2 × seeing)
- - - - Nasmyth focus
      - Cassegrain focus
      - Coudé focus
  - - - polar axis
      - declination axis
    - - height axis
      - azimuth axis

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Telescopes

Telescopes

basics

refracton and reflection

focus

image scale: S = F·θ

telescope types

telescope mounts

prime focus

Newtoian

Cassegrain

Gregorian

Schmidt-Cassegrain

Schmidt Camera

Maksutov

Refractor

Nasmyth focus

Cassegrain focus

Coudé focus

equatorial/polar

alt-az

polar axis

declination axis

height axis

azimuth axis

aberrations

spherical aberration

spherically shaped mirror has on-axis aberration

parabolic shape mirror has no spherical aberration

coma

astigmatism

distortion

Field curvature

Vignetting

Quantify the Performance

image scale: S = F·θ

plate scale: 1/F = θ/S

point source

human eye limit magnitude is 6.5

limiting magnitude: m = 5lgD + 2.5lgt + C

surface brightness

focal ratio: R = F/D or f/R

fast -- small f/R

slow -- large f/R

field of view

FOV = 2arctan(w/(2f)), w is the sensor width

Point Spread Function(PSF)

diffraction

Airy Disk: θmin = 1.22*λ/d

FWHM ~ 2.35*𝜎

PSF is often spread out in within ~4𝜎 in diameter

1.7 × seeing (i.e. within ~2 × seeing)

corrector

adaptive

active optics