Lecture 11: Telescope Design

Question 1

cassegrain reflector

Answer 1

parabolic primary
hyperbolic secondary

focus easily accessible - ideal for mounting large and heavy instrumentation

Question 2

conic sections

Answer 2

circle
ellipse
parabola
hyperbola

Question 3

parabolic mirror

Answer 3

perfect imaging on axis for object at infinity

Question 4

elliptical mirror

Answer 4

perfect imaging on axis for object at finite distance
ellipse has two foci
object and image placed at foci of ellipse

Question 5

cassegrain relflector - focus of primary forms

Answer 5

virtual object for secondary mirror

Question 6

parabolic and hyperbolic shapes ensure

Answer 6

perfect aberration free focusing for on-axis object

Question 7

ritchy-chretien reflector

Answer 7

variant on cassegrain design
concave hyperbolic primary in addition to convex hyperbolic secondary

Question 8

ritchey chretien pros

Answer 8

reduces off-axis aberrations

better performance over wider field of view due to larger secondary mirror

Question 9

spherical abberation

Answer 9

rays from edge come to focus nearer to mirror than rays from centre

Question 10

a mirror is optimised in

Answer 10

ray tracing software by varying the conic parameter