Are 16 bits really needed in CCDs and infrared detectors for astronomy?

Fernando Gago; Luis Fernando Rodriguez-Ramos; Jose V. Gigante; D. Lopez-Arozena

doi:10.1117/12.550537

29 September 2004 Are 16 bits really needed in CCDs and infrared detectors for astronomy?

Fernando Gago, Luis Fernando Rodriguez-Ramos, Jose V. Gigante, D. Lopez-Arozena

Proceedings Volume 5499, Optical and Infrared Detectors for Astronomy; (2004) https://doi.org/10.1117/12.550537
Event: SPIE Astronomical Telescopes + Instrumentation, 2004, Glasgow, United Kingdom

Abstract

One of the problems found in the design of the electronics for astronomical instruments is the difficulty to find precise digitizers (16 bits) at high speed. In fact, most of the chips which claim to have 16-bit actually have a lower ENOB (Effective Number Of Bits), normally around 14, when considering their noise effects. In this paper, a technique based in auto-adjustable gain amplifiers is proposed as a way to relax the A/D requirements for astronomical CCDs and infrared detectors. The amplifiers will automatically toggle between 2 different gains depending on the pixel value. The technique is based on the fact that, due to the shot (photon) noise of the detectors, the maximum signal to noise ratio achievable in most of these devices is relatively low, allowing the use of A/D converters with an ENOB of only 14 (or even 12) bits when combined with auto-adjustable gain amplifiers. It will be shown that the lower resolution of the A/D converters will not affect the accuracy of the science data, even when many images are averaged out to compensate the effects of the shot noise. Furthermore, given that many real A/D converters do not reach an ENOB of 16, for low level signals the accuracy can be even slightly improved with the technique described in this paper. On the other hand, this relaxing of the A/D requirements can allow the use of off-the-shelf boards for the acquisition systems.

Citation Download Citation

Fernando Gago, Luis Fernando Rodriguez-Ramos, Jose V. Gigante, and D. Lopez-Arozena "Are 16 bits really needed in CCDs and infrared detectors for astronomy?", Proc. SPIE 5499, Optical and Infrared Detectors for Astronomy, (29 September 2004); https://doi.org/10.1117/12.550537

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

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
12 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Interference (communication)

Signal to noise ratio

Amplifiers

Sensors

Analog electronics

Quantization

Electrons

Show All Keywords

Keywords/Phrases

Search In:

Publication Years