Introduction to CCD, EMCCD, ICCD

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Introduction to CCD, EMCCD, ICCD
The Speaker Leiting Pan The
Tutor Jingjun Xu
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Content

• Principle of CCD
• Parameters of CCD
• ICCD and EMCCD

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1.Principle of CCD
1.1 Development of CCD
Fig.1?????George Smith?Willard Boyle??????????????
?????CCD??
Fig.2 ??CCD????
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1.Principle of CCD
1.2 Photoelectric Conversion
Fig.3 silicon crystal have electrons arranged in
discrete energy bands The Valence Band and the
Conduction Band.
1.26eV??????1.12uM???????????,?????????,?
???????????????,?????????????????????,???????????
???,?????????????????????????,????????????????
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1.Principle of CCD
1.3 Charge Collection
Fig.4 the schematic diagram of electric potential
of single pixel.
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1.Principle of CCD
1.3 Charge Collection
Fig.5 The schematic diagram of electron produce
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1.Principle of CCD
1.4 Charge Transfer
???????,???????????????????CCD,??3??????????
????,?????????????????,??????????
Fig.6 The schematic diagram of electrons transfer
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1.Principle of CCD
5V 0V -5V
1.4 Charge Transfer
5V 0V -5V
5V 0V -5V
Time-slice shown in diagram
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1.Principle of CCD
5V 0V -5V
1.4 Charge Transfer
5V 0V -5V
5V 0V -5V
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1.Principle of CCD
5V 0V -5V
1.4 Charge Transfer
5V 0V -5V
5V 0V -5V
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1.Principle of CCD
5V 0V -5V
1.4 Charge Transfer
5V 0V -5V
5V 0V -5V
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1.Principle of CCD
5V 0V -5V
1.4 Charge Transfer
5V 0V -5V
5V 0V -5V
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1.Principle of CCD
5V 0V -5V
1.4 Charge Transfer
5V 0V -5V
Charge packet from subsequent pixel enters from
left as first pixel exits to the right.
5V 0V -5V
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1.Principle of CCD
5V 0V -5V
1.4 Charge Transfer
5V 0V -5V
5V 0V -5V
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
Fig.6 The schematic diagram of 2-D matrix
structure CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
In the split frame CCD geometry, the charge
in each half of the image area could be shifted
independently. Now imagine that the lower image
area is covered with an opaque mask. This mask
could be a layer of aluminium deposited on the
CCD surface or it could be an external mask. This
geometry is the basis of the Frame transfer CCD
that is used for high frame rate video
applications. The area available for imaging is
reduced by a half. The lower part of the image
becomes the Store area.
Image area
Image area clocks
Opaque mask
Store area clocks
Store area
Amplifier
Serial clocks
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
A common analogy for the operation of a CCD is as
follows An number of buckets (Pixels) are
distributed across a field (Focal Plane of a
telescope) in a square array. The buckets are
placed on top of a series of parallel conveyor
belts and collect rain fall (Photons) across
the field. The conveyor belts are initially
stationary, while the rain slowly fills
the buckets (During the course of the exposure).
Once the rain stops (The camera shutter closes)
the conveyor belts start turning and transfer
the buckets of rain , one by one , to a measuring
cylinder (Electronic Amplifier) at the corner of
the field (at the corner of the CCD) The
animation in the following slides demonstrates
how the conveyor belts work.
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
VERTICAL CONVEYOR BELTS (CCD COLUMNS)
RAIN (PHOTONS)
BUCKETS (PIXELS)
MEASURING CYLINDER (OUTPUT AMPLIFIER)
HORIZONTAL CONVEYOR BELT (SERIAL REGISTER)
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
Exposure finished, buckets now contain samples of
rain.
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
Conveyor belt starts turning and transfers
buckets. Rain collected on the vertical conveyor
is tipped into buckets on the horizontal conveyor.
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
Vertical conveyor stops. Horizontal conveyor
starts up and tips each bucket in turn into the
measuring cylinder .
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
After each bucket has been measured, the
measuring cylinder is emptied , ready for the
next bucket load.

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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
A new set of empty buckets is set up on the
horizontal conveyor and the process is repeated.
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
Eventually all the buckets have been measured,
the CCD has been read out.
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1.Principle of CCD
1.5 Charge Transfer of Area CCD
Fig.7 The schematic diagram of read sequence of a
CCD
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1.Principle of CCD
1.6 Pinciple of signal Acquisition in CCD

• ???????????????????????????????????,?????????????
  ?????????????,????????????,?????,?????????????????
  ???????????????????,?????????????????????????,????
  ????????
• ????????(Nyquist)??????????????,??????????????????
  ????????
• Nyquist?????????,?????????????????????????,??????
  ?????????????????,??????????????

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Image
CCD Recording
Image
CCD Recording
Centered On Pixel
On vertex of Pixels
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2.Parameters of CCD
2.1.1 Quantum Efficiency -FI CCD
They have a low Quantum Efficiency due to
the reflection and absorption of light in the
surface electrodes. Very poor blue response. The
electrode structure prevents the use of an
Anti-reflective coating that would otherwise
boost performance.
Fig.8 The schematic diagram of Thick Front-side
Illuminated CCD
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2.Parameters of CCD
2.1.2 Quantum Efficiency -BI CCD
Light enters from the rear and so the electrodes
do not obstruct the photons. The QE can approach
100 .These thinned CCDs become transparent to
near infra-red light and the red response is
poor. But Very good blue response
Fig.9 The schematic diagram of Thinned Back-side
Illuminated CCD
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2.Parameters of CCD
2.1.3 QE- AR Coatings
With an Anti-reflective coating we now have three
mediums to consider
The reflected portion is now reduced to In
the case where the
reflectivity actually falls to zero! For silicon
we require a material with n 1.9, fortunately
such a material exists, it is Hafnium Dioxide.
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2.Parameters of CCD
2.1.4 QE-FI CCD and BI CCD
Fig.10 The graph compares the quantum of
efficiency of a thick frontside illuminated CCD
and a thin backside illuminated CCD.
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2.Parameters of CCD
2.1.4 QE- Deep Depletion BI CCD
Red photons are now absorbed in the thicker bulk
of the device.
Fig.12 The graph shows the improved QE response
available from a deep depletion CCD.
Fig.11 The schematic diagram of Deep Depletion BI
CCD
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2.Parameters of CCD
2.2 Noise

• 1.Photon Shot noise (Ns)
• Incoming photons follow poisson statistics
• Given by the square root of the signal
• Important when measuring small changes over a
  large background
• 2.Readout Noise (Nr)
• Due to the preamplifier and electronics. Higher
  the speed, higher Nr
• Important in measuring low light levels e.g.
  weak fluorescence
• 3.Dark Noise (Nd)
• Thermally generated electrons in the absence of
  any light
• Cooling minimizes this noise
• Important when long exposures are required
  e.g., Luciferase imaging
• 4.Pixel response non-uniformity
• This noise source can be removed by Flat
  Fielding, an image processing technique

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2.Parameters of CCD
2.2 Noise-overall noise
Fig.13 The graph shows the total noise and the
relation with detected number of photons.
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2.Parameters of CCD
2.2.3 Noise-dark current
Fig.14 The graph shows the dark current noise is
depend on temperature.
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2.Parameters of CCD
2.2.3 Noise-dynamic range
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2.Parameters of CCD
2.3 Spatial Resolution

• For high resolution spectroscopy, we offer
  cameras with 13 µm pixel size otherwise 26 µm
  pixel size is standard.
• The higher resolution devices typically have
  slightly lower dynamic range and lower maximum
  signal to noise due the lower well capacities.

Fig.15 The picture shows the choice for pixel
size.
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2.Parameters of CCD
2.4 Time Resolution

• Fast cameras have higher read noise
• Speed also means available light is limited1000
  frames per second means 1 ms worth of light per
  frame

• Smaller field of view (ROI)
• Binning
• Read-out rate
• Vertical clock speed
• Computer

Fig.16 The picture shows the frame transfer of
CCD
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2.Parameters of CCD
2.4 Time Resolution
????F/s A B C D ??
Overlapped 133.69 106.84 31.37 31.37 31.37
Non-overlapped 72.89 66.67 26.65 26.65 26.65
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2.Parameters of CCD
2.5 Parameters of Andor EMCCD
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2.Parameters of CCD
2.5 Parameters of Andor EMCCD
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2.Parameters of CCD
2.5 Parameters of Andor EMCCD
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3.ICCD and EMCCD
3.1 Typical CCD,EMCCD,ICCD
CCDCharge Couple Device EMCCDElectron
Multiplying CCD ICCDIntensified CCD
Fig.17 Typical CCD ???
Fig.18 ECCD ???
Fig.19 ICCD ???
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3.ICCD and EMCCD
3.2.1 Basics of ICCD
Intensified CCD camera are equipped with one
or more(cascaded) image intensifier(s) that are
mounted in front of the CCD camera either fiber
optically or lens coupled. The image intensifier
is gateable and acts as fast shutter. Its gain is
adjustable.

• Ultimate sensitivity it is possible to measure
  single photons.
• UV extended spectral sensitivity down to 200 nm.
• The most important an extremely short shutter.

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3.ICCD and EMCCD
3.2.1 Basics of ICCD

• Input window capable of transmitting light over
  the range near UV visible to near IR with
  gateable photo cathode deposited on its inner
  surface.
• Micro channel plate (MCP) to provide electron
  gain.
• Output window on which a suitable luminescent
  screen (phosphor) in deposited.

Fig.20 ICCD ?????
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3.ICCD and EMCCD
3.2.2 Photo Cathode
Gating considerations The intensifier gate is
achieved giving a pulse combing from a high
voltage module. The output level if the HV-pulse
module is usually 50V to block the image
intensifier and drops to 180V during exposure
time . Due to this pulse shape
photoelectrons escape the photo cathode only
during ,i.e., the camera is only active
during ,with the high conductivity of the
photo cathode, allows the intensifier to be gated
as quickly as 5ns.
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3.ICCD and EMCCD
3.2.3 Micro Channel Plate (MCP)
Fig.21 ICCD?MCP?????

• A typical MCP consists of about 10,000,000
  closely packed channels of common diameter .
• The diameter of each channel is 10 microns.
• Every electron entering a channel in the MCP
  collides with the channel wall and produces
  secondary electrons, produce further secondary
  electrons is an electron gain up to
  . The l/d parameter (length/diameter) of the
  channels determines the maximum gain. A typical
  value is l/d40.

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3.ICCD and EMCCD
3.3.1 Principle of EMCCD
EMCCD(Electron-Multiplying CCD)??,????????
?????(On-chip multiplication)??,?????????????????
,????????,???????????????????EMCCD????CCD?????????
????(??)???????????????,???????,????????????????
????????,????1???????????2??????,?????????????????
????1???2?????????????????????????????,???????,?
???????????????????????,??????1.011.015?,?????
????????(????????????????),?????????????1000????
??????????????????????AD?????,??????????????
????,??????????????????????EMCCD??????????????????
?,AD???????????????,????EMCCD??????????????,??????
???,????????????????
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3.ICCD and EMCCD
3.3.2 Advantage of EMCCD

• ????????????CCD
• ???????????
• ????????,?????,???????????,?????????
• ????????????
• ??????

Fig.22 EMCCD??????
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3.ICCD and EMCCD
3.4 ICCD and EMCCD

• ICCD????????????,?????????50EMCCD??ccd??,???????
  ????90
• ICCD????????????????EMCCD?????????????,?ICCD????,
  ????????
• ICCD????????????,??????????(????)????????EMCCD???
  ??????,??????
• ICCD???????,???,???ICCD?????EMCCD????
• ICCD???????????????EMCCD???????????

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3.ICCD and EMCCD
Fig.23 The ICCD of Lavision corp. Germany
Fig.24 EMCCD of Andor corp. U.K.
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3.ICCD and EMCCD
????ICCD,EMCCD,LCSM,CCD pixel
???????????,?????????,?????,????,????!
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THE END
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