Astronomical application of infrared array detectors

Abstract

Major innovations in semiconductor technology have led to the recent availability to the astronomical community of arrays comprising several thousands of detectors, each simultaneously sensitive to near infrared radiation. The application of these infrared array detectors to astronomy is revolutionising the way we see the sky at these wavelengths.

Whilst similar in concept to digital imaging arrays as used by optical astronomers, there are nevertheless many areas in which the design, implementation, and optimisation of imaging arrays used in ground based near infrared astronomy differ significantly from those applied to their optical counterparts. This thesis examines the requirements for detector arrays used for astronomical near infrared imaging, and in particular examines the operation and optimisation of the recently available SBRC 62 x 58 pixel indium antimonide hybrid focal plane array. I develop a model of this array that allows us to simulate its behaviour across a wide range of observational configurations, and how its inherently non-linear response to photon illumination may be characterised and compensated for. I also develop a model that allows us to predict the sensitivity of this detector array when used in the new near infrared imaging camera (IRCAM), recently commissioned at the United Kingdom 3.8 metre Infrared Telescope on Mauna Kea, Hawaii.

Finally, I present novel infrared images of the Orion Nebula as obtained with IRCAM during the instrument commissioning. I examine the techniques used to make the observations, and to reduce the many individual frames into one single continuous mosaic. I compare the new images with previous data, and discuss the nature of several new infrared sources seen in our images, particularly with regards young stars embedded in the gas and dust of the region. These large scale, seeing limited near infrared images clearly demonstrate the large step forward taken by infrared astronomy with the introduction of imaging arrays.