Optical study on adaptive cassegrain telescope

Other Title(s)

دراسة بصرية لتلسكوب كاسكرين التكيفي

Dissertant

Ali, Shruq Mahdi

Thesis advisor

Ahmad, Muhammad Salih

University

University of Baghdad

Faculty

College of Science

Department

Astronomy and Space Department

University Country

Iraq

Degree

Ph.D.

Degree Date

2007

English Abstract

In manufacturing an adaptive mirror for use, for example, in a typical adaptive astronomical telescope, actuator and mirror design are constrained by optical, electrical and mechanical trade-offs and manufacturing process limitations.

For a certain optical design, however, the designer must have beforehand feeling of how Zernike coefficients values that are utilized by the control algorithm can affect the creation of an adequate conjugate shape on the adaptive mirror.

The main goal of this research is to obtain this feeling by examining the Zernike coefficients of an aberrated image wave-front for a typical Cassegrain system, and utilizing them to show the feasibility of designing and constructing the desired adaptive mirror.

First, several Cassegrains of different focal ratios but of the same primary (2.167m) are proposed.

Then the performance is examined by using Qbasic program.

Six cases of shortest back focal lengths but of different F1/# are thoroughly examined by employing Zemax software.

The performance of these six cases is re-examined by adding Zernike coefficients on their secondary profiles.

Second, work was concentrated on examining the performance of 2.5F1/# configuration of different secondary mirror sizes.

A configuration of 0.65 m secondary hyperbolic mirror employing eleven Zernike coefficients Z1 ,Z2 ,Z3 ,Z4 ,Z5 ,Z6 ,Z7 ,Z8 ,Z9 ,Z10 and Z11 shows a diffraction limited performance.

For F1#5 system with Zernike coefficients Z1=0.000021, Z4=0.000012 and Z11=0, the Strehl Ratio and RMS radius was 1 and 0.001 respectively.

Varying the secondary mirror dimension resulting in increasing or decreasing the coefficients values by the same scaling factor.

Main Subjects

Astronomy

Topics

• Optical properties

No. of Pages

93

Table of Contents

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-604476