Abstract:
Thirty meter telescope is one of the new class of extremely large telescopes which
have a segmented primary mirror of thirty meter of total aperture that consists of 492
hexagonal segments. Several error sources like passive alignment parameters (piston,
tilt etc.), gravity induced effects, temperature induced effect contributes to the total
science loss in the instrument. To optimize the optical performance of the telescope
all possible error sources should be studied and characterized using some optical
performance metric.
During this project I have studied some passive alignment parameters like piston and
tilt, mount induced effect due to gravity and the effects of temperature change. I have
got the optical performance in some traditional metric like RMS WFE or 80 percent
encircled energy diameter separately for different error sources. But as the error sources
provide a wide spatial frequency bandwidth, none of them is reliable to give us a
complete picture. So, a non-traditional optical performance metric, normalized point
source sensitivity metric (PSSN), is used to characterize the optical performance of the
telescope. The advantages of this metric are - it is reliable for errors having a wide
frequency bandwidth and it is multiplicative in nature. So, we can get the complete
picture by multiplying the PSSN values achieved by analysing each error sources
separately. In this thesis the detailed study of the effects of the abovementioned errors
is presented. The PSSN values for these errors were calculated separately and by
multiplying them the total science loss due to those three error sources was calculated.
