Course 7. Imaging and Display

Module 1. Flat panel displays

    1.1 Introduction    
        1.1.1 Desirability of flat panel displays
            1.1.1.1 Small size and weight
            1.1.1.2 Wall mountable
        1.1.2 Competition to cathode ray tubes
    1.2 Liquid crystal displays (LCD)
        1.2.1 Nature of liquid crystals
            1.2.1.1.Liquid in form
            1.2.1.2 Have some of the properties of solid crystals
            1.2.1.3 Materials
        1.2.2 Display operation
            1.2.2.1 Liquid crystals do not emit light
            1.2.2.2 Image generation accomplished by varying transmission
                       or reflection of the liquid crystal
            1.2.2.3 Activated by voltage applied across two plates that
                       enclose the liquid crystal
        1.2.3 Dynamic scattering type
            1.2.3.1 Uses fact that voltage causes scattering of light passing thru the material
            1.2.3.2 This was the original form, now not widely used
        1.2.4 Twisted nematic type
            1.2.4.1 Polarized light rotated thru 90 degrees by voltage
            1.2.4.2 Device between two polarizers
            1.2.4.3 Excellent display characteristics
            1.2.4.4 Relatively slow
        1.2.5 Matrix types
            1.2.5.1 Solid state device at each matrix intersection
            1.2.5.2 Switches the material at that point from one state to the other
            1.2.5.3 Use of thin film transistors
            1.2.5.4 Active matrix type
            1.2.5.5 Passive matrix type
            1.2.5.6 Matrix type LCDs are the most advanced type
        1.2.6 Properties of LCD displays
            1.2.6.1 Luminance
            1.2.6.2 Contrast ratio
            1.2.6.3 Color
            1.2.6.4 Response time
            1.2.6.5 Size
    1.3 Light emitting diode (LED) displays
        1.3.1 Solid state device
            1.3.1.1 Based on p-n junctions in semiconductors
            1.3.1.2 Electric field causes emission of light
        1.3.2 Use of LEDs in displays
            1.3.2.1 Format
            1.3.2.2 Character matrix
            1.3.2.3 Scarcity of short wavelength LEDs
        1.3.3 Properties of LED displays
            1.3.3.1 Luminous intensity
            1.3.3.2 Contrast ratio
            1.3.3.3 Color
            1.3.3.4 Response time
            1.3.3.5 Size
    1.4 Electroluminescent displays
        1.4.1 Nature of electroluminescence
            1.4.1.1 Electroluminescence is direct conversion of electric
                       energy to light a solid phosphor
            1.4.1.2 Excited by electrical field
            1.4.1.3 Involves acceleration of charge carriers to optical levels
            1.4.1.4 Materials used
        1.4.2 Types of electroluminescent displays
            1.4.2.1 Thin film electroluminescence (TFEL)
            1.4.2.2 Direct current electroluminescence (DCEL)
        1.4.3 Properties of electroluminescent displays
            1.4.3.1 Luminance
            1.4.3.2 Contrast ratio
            1.4.3.3 Color
            1.4.3.4 Resolution
            1.4.3.5 Size
    1.5 Gas discharge (plasma) displays
        1.5.1 Physical mechanism
            1.5.1.1 Ionize gas with an electric field
            1.5.1.2 Recombination radiation leads to emission of light
        1.5.2 Structure
            1.5.2.1 Matrix format
            1.5.2.2 Excitation
        1.5.3 Properties
            1.5.3.1 Luminance
            1.5.3.2 Contrast ratio
            1.5.3.3 Color
            1.5.3.4 Resolution
            1.5.3.5 Size


Module 2. Cathode ray tubes (CRT)

    2.1 Construction
        2.1.1 Electron Gun
            2.1.1.1 Heated cathode
            2.1.1.2 Control grid cylinder
            2.1.1.3 Anode
        2.1.2 Focusing
            2.1.2.1 Electrostatic
            2.1.2.2 Magnetic
        2.1.3 Horizontal & vertical deflection
            2.1.3.1 Raster scan
            2.1.3.2 Electrostatic deflection
            2.1.3.3.Electromagnetic deflection
            3.1.3.4 Comparison of electrostatic and electromagnetic deflection
        2.1.4 Screen
            2.1.4.1 Metal backing or aluminization
            2.1.4.2 Pixel format
            2.1.4.3 Phosphors
            2.1.4.4 Luminescent properties
            2.1.4.5 Persistence
            2.1.4.6 Resolution (Modulation transfer function)
        2.1.5 Color CRTs
            2.1.5.1 Types of phosphor
            2.1.5.2 Shadow masks
    2.2 Flat panel CRTs
        2.2.1 Advantage
            2.2.1.1 Conventional CRT is bulky
            2.2.1.2 Flat panel device takes much less room
        2.2.2 Channel multiplying CRT
            2.2.2.1 Two sections
            2.2.2.2 Electron gun in rear section
            2.2.2.3 Beam turned 180 degrees by electrode
            2.2.2.4 Strikes screen in front section
        2.2.3 Beam guide CRT
            2.2.3.1 Pairs of grid plates form beam guides
            2.2.3.2 Guides transfer beam parallel to screen
        2.2.4 Matrix drive and deflection
            2.2.4.1 Large array of beams
            2.2.4.2 Deflection electrodes
    2.3 High Definition TV (HDTV)
        2.3.1 Introduction to HDTV
            2.3.1.1 Requirements
            2.3.1.2 Competing technologies to CRT
        2.3.2 CRTs for HDTV
            2.3.2.1 Specifications
            2.3.2.2 Current status
            2.3.2.3 Manufacturing difficulties
    2.4 Input to CRTs
        2.4.1 Keyboards
            2.4.1.1 Standard typewriter
            2.4.1.2 Special function keys
        2.4.2 Light pens
        2.4.3 Tablets
            2.4.3.1 Capabilities for digitizing
            2.4.3.2 Electronic
            2.4.3.3 Acoustic
        2.4.4 Touch screens
            2.4.4.1 Infrared
            2.4.4.2 Resistive membrane
            2.4.4.3 Capacitive
        2.4.5 Mouse and joy sticks
    2.5 Applications of CRTs
        2.5.1 CRTs converts electrical signal into visual display
        2.5.2 Video displays
            2.5.2.1 Broadcast TV
            2.5.2.2 Video tapes
            2.5.2.3 Video discs
        2.5.3 Computer terminal
            2.5.3.1 Need high contrast
            2.5.3.2 Largely alphanumeric
        2.5.4 Instrumentation (oscilloscopes) see Module 5-2
        2.5.5 Radar
            2.5.5.1 Requires high persistence
            2.5.5.2 Include alphanumeric information
            2.5.5.3 Two dimensional presentation with beam intensity modulation
        2.5.6 Image recording
            2.5.6.1 Needs high resolution
            2.5.6.2 Transfer to recording medium
                - External focusing optical system
                - Fiber optic faceplates


Module 3. Basics of Imaging

    3.1 Basic concepts
        3.1.1 General imaging system
            3.1.1.1 Optical images captured by optics and sensor array
            3.1.1.2 Stored image is processed
                - Digitizing
                - Intensifying
                - Filtering
                - Feature extraction
            3.1.1.3 Results displayed
        3.1.2 Sampling theory
            3.1.2.1 Pixel definition
            3.1.2.2 Resoloution and spatial frequency
            3.1.2.3.Quantization
            3.1.2.4 Bandwidth
            3.1.2.5 Nyquist rate
            3.1.2.6 Discretization
            3.1.2.7 One-dimensional signals
            3.1.2.8 Two-dimensional signals (Images)
        3.1.3 Ideal systems
            3.1.3.1 Properties
            3.1.2.2.Impulse response
    3.2 Fourier transforms
        3.2.1 Definition
            3.2.1.1 Converts from time domain to frequency domain
            3.2.1.2 Fourier transforms of selected functions
        3.2.2 Properties of Fourier transform
            3.2.2.1 Convolution theorem
            3.2.2.2 Correlation theorem
        3.2.3 Two-dimensional Fourier transform
            3.2.3.1 Definition
            3.2.3.2 Lens makes Fourier transform in its back focal plane
    3.3 Spatial filters
        3.3.1 Insertion of filter in the focal plane of a lens
            3.3.1.1 Improve image quality
            3.3.1.2 Remove or enhance selected features
        3.3.2 Types of filters and their effects
            3.3.2.1 High pass
            3.3.2.2 Low pass
            3.3.2.3 Vertical pass
            3.3.2.4 Horizontal pass
    3.4 Noise in imaging systems
        3.4.1 Optical noise sources
            3.4.1.1 Signal fluctuations
            3.4.1.2 Sensor noise
            3.4.1.3 Dark current
        3.4.2 Electronic noise sources
            3.4.2.1 Johnson noise
            3.4.2.2 Amplifier noise
        3.4.3 Fourier analysis of noise
        3.4.4 Noise remediation
            3.4.4.1 Experimental design
            3.4.4.2 Digital filters
            3.4.4.3 Oversampling


Module 4. Diverse Imaging Systems and Their Applications

    4.1 Analog optical data processing
        4.1.1 Typical optical arrangement
            4.1.1.1 Two equal lenses separated by twice their focal length
            4.1.1.2 Light distribution in front focal plane of 1st lens
            4.1.1.3 Amplitude mask in rear focal plane
            4.1.1.4 Light passing thru mask goes to 2nd lens
            4.1.1.5 Detector array or other recording device at rear focal point of 2nd lens
        4.1.2 Processing
            4.1.2.1 With no mask, this forms original light distribution, but inverted
            4.1.2.2 Mask allows processing of pattern by filtering part of light
                       in transform plane
            4.1.2.3 Operations include convolution, correlation, scaling and
                       frequency translation
        4.1.3 Results
            4.1.3.1 Highly parallel processing
            4.1.3.2 Compatible with processing of data in an optical format
    4.2 Feature recognition
        4.2.1 The complex matched spatial filter
            4.2.1.1 Essentially a hologram of the feature
            4.2.1.2 Formation of complex matched spatial filters
        4.2.2 Optical arrangement
            4.2.2.1 Two equal lenses separated by twice their focal length
            4.2.2.2 Complex matched spatial filter at rear focal point of 1st lens
            4.2.2.3 Positions of desired feature appear as bright spots at
                       rear focus of 2nd lens
    4.3 Digital signal processing
        4.3.1 Principles
            4.3.1.1 May have to do analog to digital conversion on incoming signal
            4.3.1.2 Digital signal processing chips with programs for specific purposes
        4.3.2 Noise reduction in images
            4.3.2.1 Optical arrangement for image enhancement
            4.3.2.2 Sample signal at intervals and convert to digital
            4.3.2.3 Process numerical data in computer
            4.3.2.4 Compare each pixel to its neighbors and remove aberrations caused by noise
            4.3.2.5 Apply weighting coefficients to increase range of gray scale
            4.3.2.6 Convert back to analog for viewing
            4.3.2.7 Procedure can enhance image, remove clutter and increase contrast
        4.3.3 Image recognition
            4.3.3.1 Many features of images stored in memory
            4.3.3.2 Extract features from scene
            4.3.3.3 Perform correlation with each stored image
            4.3.3.4 Determine features present in scene
            4.3.3.5 Use these features to identify objects in scene
        4.3.4 Adaptive filtering
            4.3.4.1 Adapts in real time to varying conditions
            4.3.4.2 Optical arrangement for adaptive filtering
            4.3.4.3 Analog signal sampled and converted to digital
            4.3.4.4 Perform Fourier transform to analyze frequency content
            4.3.4.5 Remove unwanted frequency components
            4.3.4.6 Convert signal back to analog
            4.3.4.7 Useful for improving communication signals
    4.4 Acousto-optic processors
        4.4.1 Principles
            4.4.1.1 Moving acoustic wavefronts scatter light
            4.4.1.2 Moving acoustic wavefronts shift optical frequency
        4.4.2 Bragg devices
            4.4.2.1 Bulk Bragg cell
            4.4.2.2 Surface acoustic wave (SAW) cell
        4.4.3 Acousto-optic spectrum analyzer
            4.4.3.1 Analyzes microwave signals
            4.4.3.2 Optical arrangement
            4.4.3.3 Microwave signal converted to acoustic waves
            4.4.3.4 Light with frequency components arising from different
                       microwave frequencies is separated and sent to different detectors
        4.4.4 Acousto-optic correlation
            4.4.4.1 Two microwave signals
            4.4.4.2 Optical arrangement with SAW cell
            4.4.4.3 Laser beam split in two and interacts with SAWs
            4.4.4.4 Two laser beams heterodyned
            4.4.4.5 Time average signal proportional to correlation of microwave signals
    4.5 Applications of signal and image processing
        4.5.1 Video processing
            4.5.1.1 Image and video compression
            4.5.1.2 Target and object recognition
            4.5.1.3 Image restoration
            4.5.1.4 Medical imaging
        4.5.2 Speech and audio processing
            4.5.2.1 Automatic speech recognition
            4.5.2.2 Speech analysis and synthesis
        4.5.3 Radar and sonar signal processing
            4.5.3.1 Automatic target recognition
            4.5.3.2 Seismic data analysis
        4.5.4 Aerial photograph interpretation
            4.5.4.1 Interpretation of satellite weather data
            4.5.4.2 Search for specific military targets
        4.5.5 Industrial applications
            4.5.5.1 Production inspection
            4.5.5.2 Quality control
        4.5.6 Automated optical character recognition


Module 5. Printing and Photochemical Means of Image Display

    5.1 Printers
        5.1.1 Impact printers
            5.1.1.1 Pen type
                - Flatbed systems
                - Drum systems
            5.1.1.2 Ball printers
            5.1.1.3 Daisy wheel printers
            5.1.1.4 Wire matrix printers
        5.1.2 Electrostatic printers
            5.1.2.1 Matrix of pins which charge paper in a pattern
            5.1.2.2 Liquid toner attracted to charged areas
            5.1.2.3 Color requires four stages
        5.1.3 Ink jet printers
            5.1.3.1 Image formed by ink droplets striking paper
            5.1.3.2 Production of droplets
            5.1.3.3 Deflection of droplets
            5.1.3.4 Drop-on-demand systems
        5.1.4 Laser printers
            5.1.4.1 Electrophotography (xerography)
            5.1.4.2 Steps in the electrophotographic process
                - Charge
                - Expose
                - Develop
                - Transfer
                - Fix
                - Clean
            5.1.4.3 More detail on laser printers in Course 8
        5.1.5 Thermal printers
            5.1.5.1 Direct printing on thermally sensitive paper
            5.1.5.2 Thermal transfer printing on plain paper
            5.1.5.3 Dye sublimation thermal transfer
        5.1.6 Comparison of printing technologies
            5.1.6.1 Image quality
            5.1.6.2 Resolution
            5.1.6.3 Speed
            5.1.6.4 Color capabilities
    5.2 Recording materials
        5.2.1 Silver halide film
            5.2.1.1 Mechanism of image formation
            5.2.1.2 Processing
            5.2.1.3 D log E curve
            5.2.1.4 Resolution
            5.2.1.5 Spectral range
            5.2.1.6 Sensitivity
        5.2.2 Dry silver films
            5.2.2.1.Developed by heat    
            5.2.2.2 Resolution
            5.2.2.3 Spectral range
            5.2.2.4 Sensitivity
        5.2.3 Diazo recording
            5.2.3.1 Destruction by light of diazonium salt
            5.2.3.2 Resolution
            5.2.3.3 Spectral range
            5.2.3.4 Sensitivity
    5.3 Film-based devices
        5.3.1 Transfer from cathode ray tube screens
            5.3.1.1 Cameras to photograph CRTs
            5.3.1.2 CRTs with fiber optic face plates
        5.3.2 Film recorders
            5.3.2.1 High resolution hard copy with many colors
            5.3.2.2 Slide-making systems
            5.3.2.3 Systems for making overheads


Module 6. Electronic and Optoelectronic
Means of Modern Image Display

    6.1 Basic considerations
        6.1.1 Optical specifications
            6.1.1.1 Pixel format
            6.1.1.2 Resolution
            6.1.1.3 Brightness
            6.1.1.4 Contrast ratio
            6.1.1.5 Color
        6.1.2 Circuit interfaces
            6.1.2.1 Driver circuits
            6.1.2.2 Control circuits
        6.1.3 Packaging
            6.1.3.1 Size
            6.1.3.2 Weight
    6.2 Applications of flat panel displays
            Technology of flat panel displays has been covered in
            module 7.1 CRT displays have been covered in module 7-2
        6.2.1 Liquid crystal displays
            6.2.1.1 Laptop and desktop computers
            6.2.1.2 TV to 14 inches
            6.2.1.3 Color projector plates
            6.2.1.4 Aircraft cockpit displays
            6.2.1.5 Calculators and watches
            6.2.1.6 Telephones and FAX machines
            6.2.1.7 Dashboard displays
            6.2.1.8 Highway information displays
        6.2.2 Light emitting diodes
            6.2.2.1 TV indicators
            6.2.2.2 Electronic toys and games
            6.2.2.3 Clocks
            6.2.2.4 Appliances
            6.2.2.5 Test and medical instruments
        6.2.3 Electroluminescent displays
            6.2.3.1 Wall mounted TV
            6.2.3.2 Aircraft cockpit displays
            6.2.3.3 Industrial equipment
        6.2.4 Gas discharge displays
            6.2.4.1 Appliances and audio equipment
            6.2.4.2 Cash registers
            6.2.4.3 Portable PC monitors
            6.2.4.4.Industrial process control displays
    6.3 Emerging types of display
        6.3.1 Vacuum fluorescent
            6.3.1.1 Principles
                - Heated cathode emits electrons
                - Electrons accelerated to anode coated with phosphor
                - Phosphor emits light
                - Wire grid controls flow of electrons
            6.3.1.2 Performance
                - Usually green or blue-green in color
                - Limited number of pixels
        6.3.2 Gas-electron-phosphor displays
            6.3.2.1 High energy electrons excite phosphors
            6.3.2.2 Large screen flat panel display
            6.3.2.3 Suitable for display of computer graphics
        6.3.3 Electrophoretic displays
            6.3.3.1 Small charged colored particles suspended in dye of different color
            6.3.3.2 Particles drawn to transparent electrode by electric field
            6.3.3.3 Light reflected from surface of dye/particle mixture
            6.3.3.4 Development lags that of competing displays like liquid crystal displays
        6.3.4 Electrochromic displays
            6.3.4.1 Uses oxides of metals, like tungsten trioxide
            6.3.4.2 Oxide is oxidized or reduced by electric current
            6.3.4.3 Displays have problems with slow switching
            6.3.4.4 Potential for use in large message displays
    6.4 Projection displays
         6.4.1 Cathode ray tube
            6.4.1.1 Electron optics, phosphor screen and projection optics in single tube
            6.4.1.2 Schmidt reflector optics often used
            6.4.1.3 Three monochrome tubes used for red,green and blue
        6.4.2 Oil film light valve
            6.4.2.1 Mirror sends light from source to viscous oil surface
            6.4.2.2 Electron beam scans oil surface in video picture raster
            6.4.2.3 Surface deforms in varying amounts
            6.4.2.4 Where oil is deformed, light is reflected to projection optics
        6.4.3 Laser beam projection
            6.4.3.1 Three lasers for red, green and blue
            6.4.3.2 Rotating prism used for line scanner
            6.4.3.3 Galvanometer mirror used for vertical and frame scanner
            6.4.3.4 Laser beams sent directly to screen
        6.4.4 Liquid crystal panels
            6.4.4.1 White light separated into three primary colors, each color
                       goes to a different panel
            6.4.4.2 Light passing thru panels imaged on projector optics
            6.4.4.3 Each pixel in panel driven by thin film transistor
        6.4.5 Comparison of projection display technologies
            6.4.5.1 Image quality
            6.4.5.2 Resolution
            6.4.5.3 Size
            6.4.5.4 Cost
    6.5 High definition television (HDTV) technology
        6.5.1 Direct view cathode ray tubes
            6.5.1.1 Advantage: High quality picture
            6.5.1.2 Disadvantage: Large size
        6.5.2 Projection cathode ray tube
            6.5.2.1 Advantage: High quality picture
            6.5.2.2 Disadvantages: Large size and limited viewing angle
        6.5.3 Liquid crystal display
            6.5.3.1 Advantages: High quality picture and small size
            6.5.3.2 Disadvantages: Small picture and high cost
        6.5.4 Thin film electroluminescent display
            6.5.4.1 Advantage: Small package
            6.5.4.2 Disadvantage: Color not well developed
        6.5.5 Gas discharge displays
            6.5.5.1 Advantage: Small package
            6.5.5.2 Disadvantage: Color not well developed


Module 7. Spatial Light Modulators

    7.1 Introduction
        7.1.1 Function of spatial light modulators
            7.1.1.1 Impose desired spatial pattern on light beam computing
        7.1.2 Format
            7.1.2.1 Array of individually addressable shutters
            7.1.2.2 Shutters opened or closed to impose desired spatial pattern
            7.1.2.3 Alternatively, work in reflection and impose spatial
                       pattern on reflected beam
    7.2 Liquid crystal light valve arrays
        7.2.1 Structure
            7.2.1.1 Scattering devices
            7.2.1.2 Polarization devices
        7.2.2 Performance
            7.2.2.1 Size of arrays
            7.2.2.2 Speed
            7.2.2.3 Contrast ratio
    7.3 Magnetooptic light valve arrays
        7.3.1.Magnetooptic effects
            7.3.1.1 Faraday effect
            7.3.1.2 Kerr effect
        7.3.2 Design
            7.3.2.1 Thin film magnetooptic material on nonmagnetic substrate
            7.3.2.2 Magnetic field applied using intersecting current-carrying conductors
            7.3.2.3 Polarization of light rotated according to magnetic field
        7.3.3 Performance
            7.3.3.1 Size of arrays
            7.3.3.2 Speed
            7.3.3.3 Contrast ratio
    7.4 Acousto-optic devices
        7.4.1 Structure
            7.4.1.1 Acousto-optic modulators fabricated in arrays
            7.4.1.2 Each channel controlled by transducer and oscillator
        7.4.2 Performance
            7.4.2.1 Size of arrays
            7.4.2.2 Speed
            7.4.2.3 Contrast ratio
    7.5 Optically addressed devices
        7.5.1 Advantages of optical addressing
            7.5.1.1 Provides an all optical switching device
            7.5.1.2 No need for fast rising voltage pulses
            7.5.1.3 Very high speed
            7.5.1.4 Very low switching energy
        7.5.2 Ferroelectric-photoconductive switching devices
            7.5.2.1 Layers of ferroelectric material and photoconductor
                       between transparent electrodes
            7.5.2.2 Materials like lanthanum-modified lead zirconate titanate (PLZT)
            7.5.2.3 Device between crossed polarizers
            7.5.2.4 Ferroelectric poled in the plane of the film
            7.5.2.5 Voltage drop across the photoconductor
            7.5.2.6 Light pattern imposed on device
            7.5.2.7 Photoconductor becomes conductive and voltage drop is across ferroelectric
            7.5.2.8 Polarization switches perpendicular to plane where light intensity is high    
            5.5.2.9 Device switches from opaque to transparent where light intensity is high
        7.5.3 Optically bistable devices
            7.5.3.1 Nature of optical bistability
            7.5.3.2 Structure of a typical optically bistable switching device
            7.5.3.3 Operation of a typical optically bistable switching device
            7.5.3.4 Self-electro-optic effect devices (SEEDs)
    7.6 Applications
        7.6.1 Image overlaying systems
        7.6.2 Helmet mounted displays
        7.6.3 Miniature displays
        7.6.4 Holographic computer memories
        7.6.5 Digital optical computing


Module 8. Image Processing Equipment

    8.1 Charge-coupled devices (CCD)
        8.1.1 Principles
            8.1.1.1 Silicon integrated circuit
            8.1.1.2 Information carried by charge packets under set of clocked electrodes
            8.1.1.3 Potential wells store charge
            8.1.1.4 Charge shifted from one cell to another by varying voltage
        8.1.2 Operation as sensor
            8.1.2.1 Two dimensional array
            8.1.2.2 Image projected on array
            8.1.2.3 Charge pattern produced in array
            8.1.2.4 Sequential charge transfer to readout register
            8.1.2.5 Serial readout register shifts charge to output node for signal processing
        8.1.3 Features
            8.1.3.1 Solid state device has low power consumption
            8.1.3.2 High resolution
            8.1.3.3 Linear response, large dynamic range
            8.1.3.4 Low readout noise
    8.2 Cameras
        8.2.1 CCD cameras
            8.2.1.1 Optical design
            8.2.1.2 Line scan cameras
            8.2.1.3 Progressive scan cameras
            8.2.1.4 Frame transfer cameras
            8.2.1.5 Number of pixels
            8.2.1.6 Resolution
            8.2.1.7 Frame rete
            8.2.1.8 Color CCD cameras
        8.2.2 Image orthicons
            8.2.2.1 Uses photoemission to convert visual image to electrical signal
            8.2.2.2 Structure and operating principles
            8.2.2.3 High signal-to-noise ratio
            8.2.2.4 Works at very low light levels
        8.2.3 Vidicons
            8.2.3.1 Uses photoconductivity to convert visual image to electrical signal
            8.2.3.2 Structure and operating principles
            8.2.3.3 Spectral response
            8.2.3.4 High signal-to-noise ratio
            8.2.3.5 SEC vidicon offers high sensitivity
            8.2.3.6 Vidicons now used more than orthicons
    8.3    Computer interface equipment
        8.3.1 Basic considerations
            8.3.1.1 Input resolution
            8.3.1.2 Input accuracy
            8.3.1.3 Maximum sampling rate
            8.3.1.4 Input range
        8.3.2 Analog-to-digital (A/D) converters
            8.3.2.1 A/D converter types
                - Integrating
                - Successive approximation
                - V/F counting
                - Flash
            8.3.2.2 A/D triggering methods
            8.3.2.3 Data transfer modes
            8.3.2.4 Specifications
                - Speed
                - Resolution
        8.3.3 One-dimensional data acquisition equipment
        8.3.4 Two-dimensional data (image) acquisition equipment
            8.3.4.1 Plug-in data acquisition boards
                - Analog input boards
                - Multifunction boards
                - DC accuracy
                - Performance vs price
            8.3.4.2 Plug-ins vs external systems
                - Cost
                - Expandability
                - Portability
                - Transfer rate
            8.3.4.3 Frame grabbers
                - Real time capture of images from cameras
                - Available as plug-in cards
        `        - Differential configurations
                - Performance specifications
            8.3.4.4 Frame buffers
                - Temporary storage for acquired image
                - First-in/first-out buffers
            8.3.4.5 Scanners
                - Flatbed scanners
                - Input of photos and slides to computer
        8.3.5    Computer input
            8.3.5.1 Computer input ports
            8.3.5.2 RS-232 interface
            8.3.5.3 RS-422 interface
            8.3.5.4 IEEE-488 interface
            8.3.5.5 Peripheral Component Interconnect (PCI)\Standard for local bus
                - Boards for transfer of image to PCI bus


Module 9. Image Processing Software

    9.1 Data acquisition software
        9.1.1 Programming compared to use of integrated packages
            9.1.1.1 Programming offers higher performance, lower initial cost and greater flexibility
            9.1.1.2 Integrated package offers ease of use and shorter time to get applications started
        9.1.2 Data acquisition software packages
            9.1.2.1 One dimensional
            9.1.2.2 Two dimensional
    9.2 Image processing software
        9.2.1 Digital signal processing chips
            9.2.1.1 Prewritten for specific purposes
            9.2.2.2 Chips programmed to perform necessary steps for processing in the computer
        9.2.2 .Functions of image processing software
            9.2.2.1 Viewing
                - Acquire images
                - Load images
                - Display images
                - Annotate images
                - Measure images
            9.2.2.2 Processing
                - Refine images
                - Uses filters, morphological processes, edge detection
                - Produces enhanced images
            9.2.2.3 Geometric operations
                - Zooming
                - Rotation
                - Cutting and pasting
                - Scaling
                - Cropping
                - Warping
            9.2.2.4 Mathematical operations
                - Histograms
                - Fourier transforms
                - Correlation
                - Edge detection
            9.2.2.5 Analysis
                - Extracts numerical data on images
                - Extracts numerical data on results of processing
            9.2.2.6 Recording
                - Recording of procedures
                - Recording of results
            9.2.2.7 Display
    9.3 Specific example of image processing software: Laser beam profile determination
        9.3.1 Input
            9.3.1.1 Photodetector array systems
            9.3.1.2 CCD camera systems
            9.3.1.3 Scanning pinhole systems
            9.3.1.4 Scanning slit systems
            9.3.1.5 Scanning knife edge systems
        9.3.2 Processing
            9.3.2.1 Analog data digitized and stored
            9.3.2.2 Data from scanning systems integrated
            9.3.2.3 Gaussian fit determination
                - 2-dimensional least squares analysis
                - Image subtraction using reference Gaussian
            9.3.2.4 Generation of beam profile
                - Contour maps
                - Cross section profiles
                - Isometric plots
            9.3.2.5 Beam quality calculation
        9.3.3 Dutput of beam characteristics
            9.3.3.1 Graphics available
                - Polar plots
                - Contour plots
                - Profile plots
                - Isometric plots
            9.3.3.2 Power distribution
            9.3.3.3 TEM modes
            9.3.3.4 M2
            9.3.3.5 Spot size
            9.3.3.6 Beam divergence

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