Presentation on theme: "Toolkit for testing CCD cameras"— Presentation transcript:
1Toolkit for testing CCD cameras Janusz UżyckiFaculty of PhysicsWarsaw University of TechnologyStrona tytułowa
2CCD matrix (Charge-Coupled Devices) CCD sensors are produced in full choiceof resolution and dimenstions. They are accessible with diameter bigger than half inch. It is very important in professional astronomy applications. The CCD sensors are low noise and have high sensivity.selected resolution: 2048 x 2048 pixels,15 x 15m each
3How it works main idea of readout from CCD sensor making a photoexposure timephotonscharges vs lightempty
11How it worksthree stages of charge moving process
12Consequence of usage the CCD We had to use ownProblems- the CCD matrix- control circuits- video signal amplifieranalog to digital converter (ADC)noise, temperature of an environment, dark current, ‘hot’ pixels, sensivity gradientto find the best timmingsnoise, gain selectiondigitalization effects: offset, non-linearity etc.
13Solutions - cold environment (about -10C) - noise and infra-red radiation reduction- statistical methods for analizing „black / dark photos” – finding the best parametersExample:CCDamplifierADClightreadoutWhat is a total gain of the circuit?
14Requirements for the toolkit for testing CCD cameras designed for PC platform:Windows XP and 2000 systems(main platform for electronics)Linux system possibleIt was used ROOT library package and Microsoft Visual C++.Punkt drugi planu prezentacji
15Requirements – continuation (1) read images in fitsastronomical format which is usedby our aparature(there are raw data from the CCD)
16Requirements – continuation (2) eliminate the offset and ‘hot’ pixelsby substraction of two successive images
17Requirements – continuation (3) display picturesthe preview allows to findmain errors instantlycut egdes for analize to findthe best useful part of view
18Requirements – continuation (4) XY histogram single pixel distributionit allows to find min/max brightness of viewX and Y profile (sum or average) to find unvisible errors, dark current effect for example
19Requirements – continuation (5) X and Y profile (projection) histogramsdivide the image into regions and make single pixel histograms, fit Gauss distribution parameters (mean and sigma values) We can estimate where is a bad region.
20Requirements – continuation (6) plot chart in mean and sigma axis to fit gain line and pitch of one (tangens of angle) Here is an answer for question: What is a total gain of the circuit?electrons / ADU value = pitch of the line
21CCD Toolkit in action examples of print-screens main window(management)Trzeci punkt planu prezentacji
22CCD Toolkit in actionpreview window(enlargement)
23CCD Toolkit in actionhistogramsfor XY & profiles