SHARC II: a Caltech Submillimeter Observatory facility camera with 384 pixels

Charles Darren Dowell; Christine A. Allen; R. Sachidananda Babu; Minoru M. Freund; Matthew Gardner; Jeff Groseth; Murzy D. Jhabvala; Attila Kovacs; Dariusz C. Lis; Samuel Harvey Moseley Jr.; Thomas G. Phillips; Robert F. Silverberg; George M. Voellmer; Hiroshige Yoshida

doi:10.1117/12.459360

17 February 2003 SHARC II: a Caltech submillimeter observatory facility camera with 384 pixels

Charles Darren Dowell, Christine A. Allen, R. Sachidananda Babu, Minoru M. Freund, Matthew Gardner, Jeff Groseth, Murzy D. Jhabvala, Attila Kovacs, Dariusz C. Lis, Samuel Harvey Moseley Jr., Thomas G. Phillips, Robert F. Silverberg, George M. Voellmer, Hiroshige Yoshida

Author Affiliations +

Proceedings Volume 4855, Millimeter and Submillimeter Detectors for Astronomy; (2003) https://doi.org/10.1117/12.459360
Event: Astronomical Telescopes and Instrumentation, 2002, Waikoloa, Hawai'i, United States

Abstract

SHARC II is a background-limited 350 μm and 450 μm facility camera for the Caltech Submillimeter Observatory undergoing commissioning in 2002. The key component of SHARC II is a 12 × 32 array of doped silicon 'pop-up' bolometers developed at NASA/Goddard. Each 1 mm × 1 mm pixel is coated with a 400 Ω/square bismuth film and located λ/4 above a reflective backshort to achieve >75% absorption efficiency. The pixels cover the focal plane with >90% filling factor. At 350 μm, the SHARC II pixels are separated by 0.65 λ/D. In contrast to the silicon bolometers in the predecessor of SHARC II, each doped thermistor occupies nearly the full area of the pixel, which lowers the 1/f knee of the detector noise to <0.03 Hz, under load, at the bath temperature of 0.36 K. The bolometers are AC-biased and read in 'total power' mode to take advantage of the improved stability. Each bolometer is biased through a custom ~130 MΩ CrSi load resistor at 7 K and read with a commercial JFET at 120 K. The JFETs and load resistors are integrated with the detectors into a single assembly to minimize microphonic noise. Electrical connection across the 0.36 K to 4 K and 4 K to 120 K temperature interfaces is accomplished with lithographed metal wires on dielectric substrates. In the best 25% of winter nights on Mauna Kea, SHARC II is expected to have an NEFD at 350 μm of 1 Jy Hz^-1/2 or better. The new camera should be at least 4 times faster at detecting known point sources and 30 times faster at mapping large areas compared to the prior instrument.

Citation Download Citation

Charles Darren Dowell, Christine A. Allen, R. Sachidananda Babu, Minoru M. Freund, Matthew Gardner, Jeff Groseth, Murzy D. Jhabvala, Attila Kovacs, Dariusz C. Lis, Samuel Harvey Moseley Jr., Thomas G. Phillips, Robert F. Silverberg, George M. Voellmer, and Hiroshige Yoshida "SHARC II: a Caltech submillimeter observatory facility camera with 384 pixels", Proc. SPIE 4855, Millimeter and Submillimeter Detectors for Astronomy, (17 February 2003); https://doi.org/10.1117/12.459360

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