IOAA 2019, theory — Задача 4. Improving a common reflecting telescope

Theory problem sheet · 10 т.

Условие

A student has an average quality Cassegrain telescope, with primary and secondary mirrors having $\varepsilon_1 = 91\ \%$ reflectivity aluminium layers.

Consider the whole visual band and disregard any wavelength dependence and geometric effects.

a) What will be the change in the limiting magnitude of this telescope by replacing the mirror coatings with "premium" quality $\varepsilon_2 = 98\ \%$ reflectivity ones? (5 p) [5 т.]

b) Assuming the student also uses a star diagonal mirror, also with reflectivity $\varepsilon_1$ with the original telescope - what will be the improvement if he/she also replaces this piece with an $\varepsilon_3 = 99\ \%$ reflectivity (“dielectric” mirror) model, combined with the new $\varepsilon_2$ mirrors? (3 p) (A star diagonal mirror is a flat mirror, inclined to the optical axis by $45^{\circ}$.) [3 т.]

c) Is this difference obviously detectable by the human eye? Mark "YES" or "NO" on the answer sheet. (2 p) [2 т.]

Решение

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Оригинал в Архива: TH-problem-final.pdf · официални решения: TH-solution-final.pdf