Stray light analysis of the Apache Point Observatory 3.5-m telescope system

Stephen M. Pompea; Richard N. Pfisterer; Jeffrey S. Morgan

doi:10.1117/12.459471

30 January 2003 Stray light analysis of the Apache Point Observatory 3.5-meter telescope system

Stephen M. Pompea, Richard N. Pfisterer, Jeffrey S. Morgan

Proceedings Volume 4842, Specialized Optical Developments in Astronomy; (2003) https://doi.org/10.1117/12.459471
Event: Astronomical Telescopes and Instrumentation, 2002, Waikoloa, Hawai'i, United States

Abstract

A stray light analysis of the Apache Point Observatory 3.5 meter telescope system was done to understand the performance for a variety of imaging modes. The telescope system consists of the 3.5-m telescope, its enclosure, and its associated imaging cameras. The purpose of the study was to assess the stray light performance of this system, identify where modification(s) would improve the system off-axis rejection characteristics, and assess the effectiveness of those modifications. A detailed telescope system geometry model was created, and scatter models were created for telescope and enclosure components. The computer model we created duplicated the pinhole stray light images taken with the telescope, thereby verifying the model. The Point Source Transmittance (PST), a commonly used metric for assessing stray light was used to evaluate the stray light performance of the system for a number of off-axis angles and to suggest modifications to enhance the system. The baseline PST of the existing system shows virtually no falloff with off-axis angle in the plane of the observatory slit. This is the result of (1) the focal plane having a large, unobstructed view of the Nasmyth mirror and cell, primary mirror cell, and baffles mounted on the Nasmyth cell, (2) relatively unobstructed illumination of telescope over a large range of angles in the plane of the slit, and (3) secondary and Nasmyth baffles that are not enclosed. These attributes create a series of first-level scatter paths that directly illuminate the focal plane. Our approach to stray light reduction was to address the light paths revealed by the various PST calculations. Our calculations have shown that significant gains can be realized with simple modifications to the telescope system.

Citation Download Citation

Stephen M. Pompea, Richard N. Pfisterer, and Jeffrey S. Morgan "Stray light analysis of the Apache Point Observatory 3.5-meter telescope system", Proc. SPIE 4842, Specialized Optical Developments in Astronomy, (30 January 2003); https://doi.org/10.1117/12.459471

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available