# 3_-_Optics - 3 - Optics The Plan Three ways to follow the...

This preview shows pages 1–4. Sign up to view the full content.

3 - Optics I. Newton Newton and his reflecting telescope. ~1672 2 The Plan • Three ways to follow the track of light: – Ray tracing (optical systems) – Diffusion (in stars) – Gravitational lensing (distant galaxies) • Snell’s Law • Paraxial rays • Ray tracing • Aberrations – Spherical Aberration –Coma 3 Image quality • The atmosphere distorts the incoming wave front even further degrading the image. • Because light is a wave it is not possible to form a perfect image. (diffraction) • Bad optics further degrade the images. • How do you trace a ray through a lens and what are the aberrations? • Given a solution how is it improved. (Sorry, not this time!) 4 Diffraction θ 1.2 λ f where f = focal length/diameter and [ θ ] = [ λ ]

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
5 ~1.2 λ /D The Diffraction part of the Point Spread Function 6 Tradeoffs • The spot size (the diameter of a point source) is a combination of: – Diffraction – Geometric aberrations – Atmospheric seeing • In general the objective is to have the above contributions to the total image size to be about the same size. • Pick your battles carefully! 7 Apodization (taking the feet off) 8 It Really Works…
9 Snell’s Law n 1 sin( ϕ 1 ) = n 2 sin( ϕ 2 ) The limit of small ϕ, n 1 ϕ 1 = n 2 ϕ 2 , is called the Paraxial Limit.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 04/05/2009 for the course ASTRO 3332 taught by Professor Houck,j during the Spring '09 term at Cornell University (Engineering School).

### Page1 / 7

3_-_Optics - 3 - Optics The Plan Three ways to follow the...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online