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Revelutioning the Digital Imaging ..

Presented by:- Aritra Roy.

E.C.E. , 3rdYear.

University Roll No:- 071430103007.

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WHAT IS CCD ??????

WHAT IS CCD ?????? Charge-coupled device (CCD) is a device for the

movement of electrical charge, usually from within the

device to an area where the charge can be manipulated.

This is achieved by "shifting"

the signals between stages

within the device one at a time.

Technically, CCDs are implemented as shift registers

that move charge between capacitive bins in the device.

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BASICS OF OPERATIONBASICS OF OPERATION

In a CCD for capturing images, there is a photoactive region

and a transmission region made out of a shift register.

Image is projected through a lens onto the

capacitor array causing each capacitor to

accumulate an electric charge proportional

to the light intensity at that location.

A control circuit causes each capacitor to

transfer its contents to its neighbor as shift

register.

The last capacitor in the array dumps its charge into a charge

amplifier, which converts the charge into a voltage.

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CCD SENSOR

In CCD, the electrical field at different parts of the surface iscontrolled by an array or matrix of electrodes; called the

gates.

When light or photons of high enough

energy strike the surface, electrons

are usually liberated from the surface.

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CCD SCCD SENSORENSORAARCHITECTURERCHITECTURE

Three types of Architecture :--

1. Full-Frame CCD

2. Interline Transfer CCD

3. Frame-Transfer CCD

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IINSIDENSIDE THETHE DDIGITALIGITAL CCAMERAAMERA

Inside the digital camera, at first an IR blocking filter is there,

followed by a color separation filter called Bayer Mask.

And finally it falls on the sensor which

turns it into electrical pulses by

electron to voltage conversion.

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IIMAGEMAGE SSENSINGENSING

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CCOMPARISONOMPARISON

1. Long history of high

quality performance.

2. High Dynamic range.

3. Low noise and best dMax.

4. High power consumption.

5. Small pixel size (small

sensors - best to develop

new cameras & lenses).

6. High Fill Factor.

1. Lower performance in past,

but now providing

comparable quality.

2. Moderate Dynamic range.

3. Noisier, but getting better

quickly.

4. Relatively low power

consumption.

5. Larger pixel size (larger

sensors - easier to use withincurrent camera technology).

6. Lower Fill Factor.

CCD Sensors CMOS Sensors

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AADVANCEDDVANCED CCDCCD 3 CCD3 CCD

Three-CCD cameras have three separate

charge-coupled devices (CCDs), each one taking

a separate measurement of red, green, and blue

light.

A trichroic prism assembly splits the incoming

light and directs the appropriate wavelength of

light to their respective CCDs.

Compared to one CCD cameras , three-CCD cameras generallyprovide superior image quality and resolution. By taking separatereadings of red, green, and blue values for each pixel, three-CCDcameras achieve much better precision than single-CCD cameras.

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FFURTHERURTHERAADVANCEMENTSDVANCEMENTS

Electron Multiplying CCD (EMCCD):-

In EMCCD a gain register is placed in

between shift CCD register and output

amplifier, to reduce readout noise.

Super CCD:- It uses octagonal pixels for higherhorizontal and vertical resolution at expense of

diagonal resolution than a traditional sensor.

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AAPPLICATIONPPLICATION

In Astronomy:-

In Digital Cameras:-

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