The CCD sensor was invented in 1969 by Willard Boyle and George E. Smith of AT&T Bell Labs.

Originally intended as a memory device

Pixel: Picture Element CCD: Charge-Coupled Device CMOS: Complimentary Metal-Oxide

Semiconductor Panchromatic: Sensitivity to a wide

range of wavelengths of light.

1. Photoelectric effect creates an electron-hole pair when light impinges upon a semiconductor

2. Each pixel accumulates a charge3. When sampled, the “bucket of charge”

for each pixel is transported off-chip to on off-chip amplifier

4. A capacitor is used to convert the charge to a voltage. V = q/C

Used largely in military and scientific applications.

The image-intensifier is added to a CCD to create an intensified CCD.

Provides single-photon sensitivity Also enables extremely short exposure

times. (down to 200ps) It reduces the shortcomings of a bare

CCD

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A: 200V Gating Voltage (variable)B: 1000V Micro-channel plateC: 6kV acceleration voltage

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A: 200V Gating Voltage (variable)B: 1000V Micro-channel plateC: 6kV acceleration voltage

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Is officially defined as the percentage of photons hitting a surface that will produce electron-hole pairs› Regular photographic film is about 10%› Human Eye is about 3%› CCDs can have a QE of more than 90% at

some wavelengths Useful for rating solar cells Doesn’t account for unwanted

recombination in material

Quantum Efficiency of CCD used in Hubble Space Telescope’s

Wide-Field and Planetary Camera 2

When charges are shifted from pixel to pixel it is the loss associated with each shift. A value of 0.999 is actually bad!

Most CCDs use 2000-4000 shifts to read a single pixel out.

Thermal excitations can excite electrons into the conduction band

This is the reason that most CCDs require extensive cooling (-90 to -40 °C)

Electronic amplifiers are not perfect and introduce their own noise.

This determines the “noise floor” of the CCD. It sets the limitation of how faint of an object a CCD can see.

Optically insensitive structures for each pixel (absorption loss)

Natural reflection of certain wavelengths (reflection loss)

Very long and very short wavelengths pass straight through sensor without generating an electron (transmission loss)

CCDs are simple application of the photoelectric effect

Intensified CCDs improve the light sensitivity of a bare CCD

Intensified CCDs are used in military and scientific application (mostly astronomy)

http://www.asiimaging.com/pdfs/Comparison_of_CCD_Cameras_to_an_Ideal_Camera.pdf

http://www.andor.com/learn/digital_cameras/?docid=326 http://www.dalsa.com/dc/documents/

Image_Sensor_Architecture_Whitepaper_Digital_Cinema_00218-00_03-70.pdf

http://www.dalsa.com/markets/ccd_vs_cmos.asp http://www.iccd-camera.com/technology_main.html http://en.wikipedia.org/wiki/Quantum_efficiency http://wfc3.gsfc.nasa.gov/MARCONI/machines-see.html