2 July 2010 PSF and MTF measurement methods for thick CCD sensor characterization
Author Affiliations +
Knowledge of the point spread function (PSF) of the sensors to be used in the Large Synoptic Survey Telescope (LSST) camera is essential for optimal extraction of subtle galaxy shape distortions caused by gravitational weak lensing. We have developed a number of techniques for measuring the PSF of candidate CCD sensors to be used in the LSST camera, each with its own strengths and weaknesses. The two main optical PSF measurement techniques that we use are the direct Virtual Knife Edge (VKE) scan as developed by Karcher, et al.1 and the indirect interference fringe method after Andersen and Sorensen2 that measures the modulation transfer function (MTF) directly. The PSF is derived from the MTF by Fourier transform. Other non-optical PSF measurement techniques that we employ include 55Fe x-ray cluster image size measurements and statistical distribution analysis, and cosmic ray muon track size measurements, but are not addressed here. The VKE technique utilizes a diffraction-limited spot produced by a Point-Projection Microscope (PPM) that is scanned across the sensor with sub-pixel resolution. This technique closely simulates the actual operating condition of the sensor in the telescope with the source spot size having an f/# close to the actual telescope design value. The interference fringe method uses a simple equal-optical-path Michelson-type interferometer with a single-mode fiber source that produces interference fringes with 100% contrast over a wide spatial frequency range sufficient to measure the MTF of the sensor directly. The merits of each measurement technique and results from the various measurement techniques on prototype LSST sensors are presented and compared.
© (2010) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
P. Z. Takacs, P. Z. Takacs, I. Kotov, I. Kotov, J. Frank, J. Frank, P. O'Connor, P. O'Connor, V. Radeka, V. Radeka, D. M. Lawrence, D. M. Lawrence, } "PSF and MTF measurement methods for thick CCD sensor characterization", Proc. SPIE 7742, High Energy, Optical, and Infrared Detectors for Astronomy IV, 774207 (2 July 2010); doi: 10.1117/12.856738; https://doi.org/10.1117/12.856738


MTF measurement technique for GOES imager
Proceedings of SPIE (August 25 1998)
Phase-shifting Zernike interferometer wavefront sensor
Proceedings of SPIE (September 26 2011)
Characterization of prototype LSST CCDs
Proceedings of SPIE (July 21 2008)
System Design Considerations Of CCD Based Line Imagers
Proceedings of SPIE (August 23 1988)
Dynamic Response Of An Electro-Optical Imaging System
Proceedings of SPIE (September 04 1989)

Back to Top