Experimental measurement of the variation in sensitivity within a single pixel of a CCD

Kavaldjiev, Daniel; Ninkov, Zoran

doi:10.1117/12.275189

Cited by 7 publications

(6 citation statements)

References 3 publications

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“…Diffusion has been measured with a knife edge, 2 a focused light beam, 3,4 or a pinhole mask. 5 We demonstrate a novel method of measuring the charge diffusion in a CCD.…”

Section: Introductionmentioning

confidence: 99%

Charge diffusion in the field-free region of charge-coupled devices

et al. 2010

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The potential well in back-illuminated charge-coupled devices ͑CCDs͒ does not reach all the way to the back surface. Hence, light that is absorbed in the field-free region generates electrons that can diffuse into neighboring pixels and thus decreases the spatial resolution of the sensor. We present data for the charge diffusion from a near point source by measuring the response of a back-illuminated CCD to light emitted from a submicron diameter glass fiber tip. The diffusion of electrons into neighboring pixels is analyzed for different wavelengths of light ranging from 430 to 780 nm. To find out how the charge spreading into other pixels depends on the location of the light spot; the fiber tip could be moved with a piezoelectric translation stage. The experimental data are compared to Monte Carlo simulations and an analytical model of electron diffusion in the field-free region. The presented analysis can be used to predict the charge diffusion in other back-illuminated sensors, and the experiment is universally applicable to measure any type of sensors.

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“…Diffusion has been measured with a knife edge, 2 a focused light beam, 3,4 or a pinhole mask. 5 We demonstrate a novel method of measuring the charge diffusion in a CCD.…”

Section: Introductionmentioning

confidence: 99%

Charge diffusion in the field-free region of charge-coupled devices

et al. 2010

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“…Note, however, that the measured pixel response variations inside the pixel active area may not necessarily be silicon related, but could be due to microlens imperfections. In many of the prior studies ( [6], [7], [8], [9]), the IPS variation is extracted by the deconvolution method. We therefore compare our forward modeling method with the deconvolution method.…”

Section: Resultsmentioning

confidence: 99%

“…[6] presents a new Continuous Self-Imaging Grating (CSIG) technique to measure the IPS map of the CCD in the framework of Euclid mission. Most prior publications studied extensively the IPS variation profiles of front and back illuminated CCDs [7], [8], [9], [10], but so far, few studies have been done on CMOS image sensors [11].…”

Section: Introductionmentioning

confidence: 99%

Measuring Intra-Pixel Sensitivity Variations of a CMOS Image Sensor

Mahato

Meynants²,

Raskin

et al. 2018

IEEE Sensors J.

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Some applications in scientific imaging, like spacebased high-precision photometry, benefit from a detailed characterization of the sensitivity variation within a pixel. A detailed map of the intra-pixel sensitivity (IPS) allows to increase the photometric accuracy by correcting for the impact of the tiny sub-pixel movements of the image sensor during integration. This paper reports the measurement of the sub-pixel sensitivity variation and the extraction of the IPS map of a front-side illuminated CMOS image sensor with a pixel pitch of 6 µm. Our optical measurement setup focuses a collimated beam onto the imaging surface with a microscope objective. The spot was scanned in a raster over a single pixel to probe the pixel response at each (sub-pixel) scan position. We model the optical setup in ZEMAX to cross-validate the optical spot profile described by an Airy diffraction pattern. In this work we introduce a forward modeling technique to derive the variation of the IPS. We model the optical spot scanning system and discretize the CMOS pixel response. Fitting this model to the measured data allows us to quantify the spatial sensitivity variation within a single pixel. Finally, we compare our results to those obtained from the more commonly used Wiener deconvolution.

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“…It causes an extra source of noise in the integrated flux signal because of the slight movement of the point spread function (PSF) within a pixel due to spacecraft pointing jitter. Intra-pixel sensitivity profiles of the front as well as back illuminated CCD's were studied extensively [2]- [5] but a few works have been done on CMOS image sensor [6]. To understand the scientific imaging capability, one must therefore characterize the intra-pixel sensitivity variation of the CMOS image sensor.…”

Section: Introductionmentioning

confidence: 99%

A novel technique to characterize the spatial intra-pixel sensitivity variations in a CMOS image sensor

Mahato

Meynants

Raskin

et al. 2017

2017 15th IEEE International New Circuits and Systems Conference (NEWCAS)

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To understand the scientific imaging capability, one must characterize the intra-pixel sensitivity variation (IPSV) of the CMOS image sensor. Extracting an IPSV map contributes to an improved detector calibration that allows to eliminate some of the uncertainty in the spatial response of the system. This paper reports the measurement of the sub-pixel sensitivity variation and the extraction of the 2D IPSV map of a front-side illuminated CMOS image sensor with a pixel pitch of 6 μm. Our optical measurement setup focuses a collimated beam onto the imaging surface with a microscope objective. The spot was scanned in a raster over a single pixel and its immediate neighbors in order to probe its response at selected (sub-pixel) positions. In this work we introduced a novel technique to extract the IPSV map by fitting (forward modeling) the measured data to a mathematical model of the image, generated in a single pixel that allows for a spatially varying sensitivity.

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Experimental measurement of the variation in sensitivity within a single pixel of a CCD

Cited by 7 publications

References 3 publications

Charge diffusion in the field-free region of charge-coupled devices

Charge diffusion in the field-free region of charge-coupled devices

Measuring Intra-Pixel Sensitivity Variations of a CMOS Image Sensor

A novel technique to characterize the spatial intra-pixel sensitivity variations in a CMOS image sensor

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