1 Introduction General introduction to the course, introduction lecturer, introduction participants, course objectives, historic overview of solid-state image sensors, literature, conferences, periodicals, applications and links to specific websites 60 30 30 50 30 20 0 2 Semiconductor Physics A review of the semiconductors physics related to electrical conduction in silicon, Si doping with P and As : n-type silicon, Si doping with B : p-type silicon 20 0 0 20 0 0 0 3 MOS Capacitor MOS capacitor in accumulation, depletion, deep-depletion and weak inversion 20 20 20 30 20 0 0 4 Charge Transport Transporting a charge packet from one MOS-capacitor to the next one 20 20 10 20 10 0 0 5 CCD Transport Transporting a charge packet from one CCD cell to the next one, channel definition, 4-phase transport, 3-phase transport, 2-phase transport, single phase transport, virtual CCD, channel definition 35 35 10 35 0 0 0 6 Input Structures CCD electrical input structure by means of a fill-and-spill method 10 10 0 0 0 0 0 7 MOS Transistor Working principle of the MOS transistor : cut-off, linear region, saturation region, source-follower configuration, offset differences between source-followers 15 15 15 15 15 0 0 8 Output Structures CCD output structure, CMOS active pixel output structure, floating diffusion amplifier, conversion factor/gain 35 25 25 35 25 0 0 9 Photodiodes Working principle of photodiodes, photodiode in integration mode, reset of photodiodes, pinned-photodiodes, fully depleted pinned-photodiodes, n-type and p-type pixels 20 10 20 20 20 20 0 10 Photon Sensing By means of a photogate or photodiode, readout by means of a CCD register or CMOS readline 10 0 10 10 0 0 0 11 One Dimensional Imagers Linear, Bi-linear and Quadri-linear arrays 15 15 0 15 0 0 0 12 Two Dimensional Imagers Working principle of the Frame-Transfer CCD, Full-Frame CCD, Interline Transfer CCD, Frame Interline Transfer CCD, XY-MOS sensor, rolling shutter versus global shutter 40 40 20 40 20 30 0 13 CMOS Imagers Two-dimensional CMOS array with passive and active pixels, without ADC, with single ADC, with column level ADC and with pixel level ADC 25 10 25 25 10 0 0 14 A-to-D Converters Flash ADC, Single-Slope ADC, Sigma-Delta ADC, Successive Approximation ADC, Cyclic ADC, Pipelined ADC. How many bits are needed for a certain application? 25 0 0 25 0 0 0 15 CMOS Pixels Passive Pixels, APS with photodiodes, APS with photogates, APS with pinned-photodiodes, shared pixel concept, pinned-photodiodes with 3T, logarithmic pixels, correlated-double sampling, data-double sampling, example of circuit diagram, example of pixel lay-out, wide-dynamic range pixels, global shutter pixels, pinned photodiodes 65 0 50 65 50 50 0 16 CMOS Scaling What is the effect of Moore's Law on the imaging performance of CMOS image sensors ? What is the effect on pixel size and fill factor ? 25 0 25 25 25 0 0 17 CMOS versus CCD What are the major differences between both technologies ? Cost, power consumption, functionality, image quality 25 0 25 25 0 0 0 18 Economics of Imagers Why are solid-state imagers that expensive ? What is the impact on cost when more circuitry is integrated on the imaging chip ? 20 0 20 0 0 0 0 19 Scanning Modes TV standards. Progressive scanning, interlaced scanning, non-interlaced scanning 30 20 10 30 0 0 0 20 Switchability Switching between 2 aspect ratios while keeping the number of line on imager constant 25 25 0 0 0 0 0 21 Smear Smear in frame-transfer CCD, in interline-transfer CCD and in CMOS image sensor 25 25 0 25 0 0 0 22 Optics Brief overview of geometric optics : positive lens, negative lens, lens aberrations, field-of-view, depth-of-field, F-number, diffraction limit, lens MTF 90 0 0 60 90 0 0 23 Dark Current Dark current, dark current fixed-pattern noise, dark shot noise : where does it come from ? how to correct ? how to reduce ? temperature effect on dark current 60 40 40 60 0 0 0 24 Transport Inefficiency What is the effect of transport inefficiency on the image quality ? 10 10 0 0 0 0 0 25 Buried Channel CCD Surface channel and Buried channel CCDs 10 10 0 10 0 0 0 26 Blooming and Anti-Blooming What is blooming and how to avoid : anti-blooming by clocking, or lateral anti-blooming, vertical anti-blooming, anti-blooming in CMOS image sensors 20 20 10 20 0 0 0 27 Electronic Shutter Electronic charge reset or integration time shortening, rolling shutter versus global shutter, flickering, global shutter pixels with 4T, 5T, 6T and 7T, pipelined shuttering pixels, global shuttering in the charge and in the voltage domain 45 35 35 45 35 50 0 28 Resolution What is the effect of number of pixels on the image quality ? 5 0 0 5 0 0 0 29 Sampling What is the effect of sampling on image quality ? Nyquist theorem, aliasing, Moire-effects 35 0 0 35 0 0 0 30 Modulation Transfer Function Geometrical MTF, Moire-effects, effect of the fill-factor on geometrical MTF, eye MTF, film MTF 50 0 0 50 0 0 0 31 Light Sensitivity Absorption coefficient, light absorption in silicon, generation of electron-hole pairs, collection of charge carriers, spectral response, quantum efficiency, optical formats, cross-talk 55 45 45 55 25 0 0 32 Colour Imaging Why is colour imaging so difficult ? Colour diagrams, colour imaging by means of a rotating filter wheel, by means of a colour prism, by means of silicon as colour splitter and by means of colour filters, stripe filters, mosaic filters, Bayer pattern, interpolation or demosaicing, colour matrixing, effects on sensor resolution 100 60 60 100 60 0 0 34 Noise Definition of kTC noise, reset noise, correlated-double sampling, 1/f noise, RTS noise, thermal noise, quantization noise, dark shot noise, transfer-gate noise, photon shot noise, dark fixed-pattern noise, light fixed-pattern noise, leakers, soft errors, hard errors, defects, perception of noise, transfer curve of an image, cosmetic defects, radiation damage 150 120 120 150 150 240 0 35 Number of Photons/Electrons How many electrons does one get in a pixel for a certain amount of light input ? How many Volts does one get at the output of the sensor for a certain amount of light input ? 25 0 0 0 25 0 0 36 Dynamic Range Definition of dynamic range, influence of integration time, temperature and pixel frequency on dynamic range, wide-dynamic range pixels, pixels with multiple gain, multiple exposures, pixels with multiple photodiodes 30 20 20 30 0 0 0 37 Noise as a Measurement Tool Using the typical photon shot noise characteristics as a measurement tool for analyzing solid-state sensors or cameras, photon transfer curve, photon shot-noise method, mean-variance method, practical use of the photon shot noise method, noise as a diagnostic tool, photon transfer curve by means of multiple images, by means of 3 images, by means of 2 images and by means of a single image 30 30 30 30 30 60 0 38 Signal-to-Noise Ratio Definition of signal-to-noise ratio, effect of manipulation of images on signal-to-noise ratio : adding images, subtracting images, multiplying/dividing images 35 15 15 35 15 0 0 39 Increasing Light Sensitivity How can the light sensitivity of an imager being increased : use of micro lenses and its limitations, optimization of the multi-layer structures, amorphous silicon top layers, back-side illumination, binning in the charge domain, in the voltage domain and in the digital domain, light pipes, increase of near-IR sensitivity for Si devices 85 30 30 75 0 60 0 40 Special Developments Building-block concept and stitching, sub-sampling, binning, multi-mode CCD, super-CCD, Time-Delayed Integrating, electron-multiplying CCD, image sensors for SWIR 55 25 0 55 0 60 0 41 How CCDs Are Made An overview of the CCD production process is given in 60 sheets : from bare silicon substrates till a complete device with colour filters and micro lenses 30 30 0 0 0 0 0 44 How To Measure ? The dark current, dark non-uniformities, light non-uniformities, light sensitivity, quantum efficiency, saturation level, linearity, conversion gain, MTF (Siemens Star, slanted edge), transport efficiency, cross-talk and image lag 80 0 0 80 80 0 0 45 Analysis of Specifications The data-sheets of 3 existing CMOS image sensors are analyzed and compared with each other 60 0 45 45 0 0 0 46 Image Processing Binary Tips, Look-Up Table, Histograms, Histogram Stretching, Processing with a Kernel, Low-Pass Filtering, High-Pass Filtering, Median Filtering, Fourier Transform 60 0 0 0 60 0 0 47 Auto-White Balancing Why is auto-white balance needed ? Metamerism of the human eye/brain, AWB based on the Grey World, AWB based on White Points, adaptive thresholds in AWB 35 0 0 0 35 0 0 48 Optical-Low-Pass Filtering Why is optical-low-pass filtering needed ? How is it implemented ? Contouring and unsharp masking 30 0 0 0 30 0 0 49 Vignetting Lens vignetting, sensor vignetting. Correction of vignetting : intensity and sharpness correction 30 0 0 0 30 0 0 50 Matrixing Why is colour matrixing needed ? Influence of colour filters, sensor quantum efficiency, cover glass, lens transmission. Relation between matrix coefficients and signal-to-noise ratio, how to find the matrix coefficients, using weighting factors to optimize the matrix coefficient 80 0 0 0 80 0 0 51 Demosaicing Bilinear interpolation, interpolation based on constant hue, gradient based interpolation, adaptive interpolation, luminance-chrominance based interpolation, adaptive luminance-chrominance interpolation 50 0 0 0 50 0 0 52 Dark Current Correction correction by means of black lines/columns, correction by means of a single dark frame subtraction, correction by means of multiple dark frame subtraction, correction in the case of long exposure times, correction in the case the camera has no mechanical shutter 30 0 0 0 30 30 0 53 Column FPN Correction Column FPN correction by means of a measured correction signal, influence of temporal noise on the column FPN correction 20 0 0 0 20 30 0 54 Defects Correction Correction of defects in the case the address of the defect is known and in the case the address of the defect is unknown, detection of defects, correction of defect columns 20 0 0 0 20 0 0 55 Noise Filtering Noise reduction by means of low-pass filtering, by means of adaptive filtering, K nearest neighbour algorithm, sigma filter, salt-and-pepper noise filtering, median filtering in one and two dimensions 35 0 0 0 35 0 0 56 Auto Exposure Definition of ideal exposure, analog gain, digital gain, global correction, local correction 0 0 0 0 0 0 0 57 Auto Focus contrast detection method, phase detection method, PDAF pixels, extended depth-of-field 0 0 0 0 0 0 0 58 Camera System Complete overview of all the artefacts discussed and all correction methods applied. A clear insight is given how the correction of one particular artefact can influence the correction of another one 20 0 0 20 20 0 0 59 Demonstration Live demonstration of several image sensor aspects : dark current, fixed-pattern noise, resolution, thermal noise, power supply noise, dynamic range, light sensitivity, black-level control 60 0 0 40 0 10 0 60 Human Eye Comparison is being made between the human eye on one hand and the CMOS and CCD sensors on the other hand 15 15 15 15 15 0 0 61 Evaluation Closure and evaluation of the course 10 10 10 10 10 0 0 62 Exercises Practical exercises on various topics are available : clock generation for the sensor, timing, power dissipation, dark current distribution and non-uniformities, electronic shuttering, colour interpolation, dynamic range, smear, signal-to-noise, noise, conversion of units, camera systems, etc. 840 0 0 380 0 0 0 63 Hands-On Evaluation in-class evaluation of image sensors and cameras, dark current, dark fixed-pattern noise, noise floor in dark, performance, light performance such as PRNU, linearity, full well, MTF, light sensitivity, etc. 0 0 0 0 0 0 750 64 Recent Developments What are new developments in the CIS world, introduced in the last 12 months ? 180 0 0 0 0 0 0
