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Hi-Res CCD Camera Survey,

A.K.A., Misc Camera Stuff


Counter Rotating Cameras
Image Capture
Differential Gearing.

Stepper Motor.

Permanent-magnet Generator powers Cameras.

Bi-directional Optical Data Transfer.



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Image Capture Block Diagram
Image Capture (showing green channel only) & Variable Gain Amplifier
Image Capture (showing green channel only) & Multiplying DAC for variable gain module
8 bit Offset & 8bit Gain Control


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Table 1 CCD Sensor Survey
Mfg.
Part #
Size
Pixel.Rate #Pixels Frm Rate
_Dim_
  Fill 
Factor
Dy Rng Note
Anti
Blom
& Intgn
Sec- 
tions
Price
                           
DALSA IA-D2-1024 1024.x 1024 16 MHz 1.05M . 10ux10u     3k:1 . . . $
DALSA IA-D9-2048 
MEGASENSOR_TM
2056 x 2056 60 MHz 4.23M 14 f/sec 12u x 12u   100% 3k:1 . . 4 $
DALSA IA-D9-5000 
MEGASENSOR_TM
5000 x 5000 60 MHz 25M 2.f/sec 
4f/sec
NOTE_[2]
12u x 12u   100% 2k:1 requires
Shutter
NOTE_[1]
.. 4 $
Mfg.
Part #
Size
Pixel.Rate #Pixels Frm Rate
Dim
  Fill 
Factor
Dy Rng Note
Anti
Blom
& Intgn
   
LORAL CCD422 1024.x.1024 . .   15u x 15u .   10k:1 requires
Shutter
NOTE_[1]
. 2 $
LORAL CCD441 2048 x 2048 . .   7.5x7.5 .   . requires
Shutter
NOTE_[1]
. . $
LORAL CCD442 . . .   . .   10k:1 requires
Shutter
NOTE_[1]
. . $
TI TC215 1000 x 1018 20MHz .   . 15fps   60dB anti- 
bloomg
yes 2 $
Mfg. Part # Size Pixel.Rate #Pixels   . Frm Rate   Dy Rng Note Anti
Blom
& Intgn
Sec- 
tions
Price
NOTES:
[1] The device needs to be covered during readout:

The photosite structure is made up of contigouous CCD elements with no voids or inactive areas. In addition to sensing light, these elements are used to shift image data vertically, that is, there is no buffer memory below the photosites as is usual in most CCD sensor arrays. Consequently, the device needs to be covered during readout.

[2]

Camera Metrics
(what is needed)
Optical (Lens) Speed
Depth of Field
Dynamic Range / S/N ratio
  (>14bits, 84dB)
Exposure Control
(Antiblooming & Integration Control)
E x p o s u r e
What WLs are Needed? RGB? UV-NIR?
Spectral Efficiency
(Sensitivity)
Analog SignalProcessing
Correlated DoubleSampling
D.C. Restore
Dynamic Range Extending
Ideal Random Access Pixels, RAP
Spectral Bandwidth
(< 300nm to > 900nm)
S/N Enhancment
(TEC) 6deg = 6dB
ADC 12 bit - 14 bit Programmable Gain
(ADC Reference)
Stacked Sensors
1st Set for Overexposure (Blooming)
2 nd Set for Underexposure (Noise)
Combined: Extends Dynamic Range
Sequential Color
Color Wheel
Digital PRNU Compensation (Gain & Offset) Spatial Resolution (pixels) Image Sharing with Multiple Stacked & Registered CCD Array Sensors
Interference
Optical Communications WL
LASER Blinding
Sun Light Reflections, Glare
  Sub-pixel Shifting
PiezoShifter
(see Pixel Shift rule)
Optical Considerations
Relay Lens Arrangement
Beamsplitter
Focal Plane for Each WL (compensation)
Other Sensors UV, NIR, FIR
Fixes for Errors:
Kinks
Video Encoding/Adaptive Gain Ranging
Large Area CCD Area Arrays
(a Survey)
Temporal Resolution
Frame Rate
Pixel Sample Rate
---- C C D   C a m e r a   A r c h i t e c t u r e  ----
System Block Diagram
Pixel Shifting for increased Resolution
(Each Camera's view is offset < 1 photosite spacing, looking at different parts of the same image).

 

  Various Modes of Speed / Resolution Tradeoff 
   P i e z o  S h i f t e r
If two sensors are shifted the distance of 1/2 photosite spacing in the X axis relative to the two remaining cameras: the horizontal resolution would be doubled; the vertical resolution is unchanged; the horizontal frame rate has been reduced by 1/2; the vertical image resolvable picture elements is unchanged

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..
    All CCD sensors have a variation in gain and offset between photosites; this is known as PRNU, or Photosite Non-uniformity.
    Its effect is to limit the apparent S/N ratio. However, since it is a stationary phenomenon--unlike dark noise--it can be characterize,
    mapped and ultimately canceled out. This can be accomplished either as a analog subtraction at the ADC input, or as a
    digital subtraction--as in the figure--a LUT stored map of the gain and offset coefficients.
CCD, Analog to Digital Convertor, Host Interface
With Lowpass Filter, Correlated Double Sampling, D.C. Restore,
Programmable ADC Reference, Local Timing & Control, and Digital PRNU Compensation


 
 

A r c h i t e c t u r e
Stacked cameras: 
Large Area CCD Area Array -- Options --

CCD Array
Size
# Pixels
Frame Rate
Pixel Rate
Frame
Rate
Pixel Rate
1k x 1k 1,048,576 x 30 31,457,280/sec x 60  62,914,560/sec
           
Coverage:
x = 120deg.
y = 120deg.
3 cameras
8.53pixel/deg.
 
Coverage:
x = 60deg.
y = 60deg.
12 cameras
17.06 pixel/deg.  
           
CCD Array
Size
# Pixels
Frame Rate
Pixel Rate
Frame
Rate
Pixel Rate
2k x 2k 304,194,304
x30
125,829,120/sec
x 60
251,658,240/sec
           
Coverage:
x = 120deg.
y = 120deg.
3 cameras
17.06 pixel/deg.  
Coverage:
x =  60deg.
y =   60deg.
12 cameras
34.13 pixel/deg.  

Dynamic Range & S/N ratio

 Exposure Control 

 
Wish List:
Random Access Pixels, (RAP)
In the best of all worlds: It would be of great benefit if Area Array CCD architecture enabled access and control of individual photo sites--random access pixels, RAP.

By selectively emptying overexposed photosites before blooming (overflowing their wells); and allowing other underexposed photosites to integrate longer (for periods >frame interval)--absolute exposure on a pel by pel basis--dynamic ranges order of 2 x (S/N dB) of the sensor might be attainable. ( this assumes other features of this architecture are employed) [2]
 

Until RAP is Available:
Two cameras stacked & registered (looking at the same scene): one camera's exposure is predicated on the brightest part of the scene--peak light; the second camera's exposure is based on some deterministic lower light level, thereby capturing previously noisy parts of the scene. Of course, the over exposed image data from that sensor is useless and discarded--as is the noisy data from the other camera. 

By combining the best of both sensors the overall dynamic range of such a system is enhanced in one of two ways:. 

The temporal resolution of the extreme areas (noisy & over exposed) is equal to one camera, while the non-extreme areas--gooddata--are equal to the sum of both cameras. 

If the two cameras are setup for maximum spatial resolution--in the staggered pixel mode--then the spatial resolution of the two extreme areas (noisy & over exposed) is equal to one camera, and the non-extreme areas--when combined--are equal to the sum of both cameras ( i.e., resolution = X2). 
 

Stacked cameras:

The photosites of each camera are registered on the same scene elements.

Each camera is transfering its image sequentially in concert with the other cameras, having the effect of increased frame rate (1 camera FR = 7.5 FPS; 4 cameras, effective FR = 30 FPS).

Each camera's sensor has the property of shifting its registration a few microns in either X and/or Y directions.

If two cameras were shifted the distance of 1/2 photosite spacing in the X axis relative to the two remaining cameras: the horizontal resolution would be doubled; the vertical resolution is unchanged; the horizontal frame rate has been reduced by 1/2; the vertical image resolvable picture elements is unchanged

Max Frame Rate, all cameras registered on same image, outputting twice as fast as one camera 

Max Resolution: Each camera offset, looking at different parts of the same image     (between photo sites).. 

Best of Both: In a multiple camera--more than two--there can be a "Mix & Match' arrangement: some cameras     grouped for max frame rate , while the rest are setup for max resolution. 


Some areas of a scene are over exposed (blooming) while other areas are under exposed --noisy. 



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Scenario:
Two cameras stacked & registered (looking at the same scene): one camera's exposure is predicated on the brightest part of the scene--peak light; the second camera's exposure is based on some deterministic lower light level, thereby capturing previously noisy parts of the scene. Of course, the over exposed image data from that sensor is useless and discarded--as is the noisy data from the other camera. 

By combining the best of both sensors the overall dynamic range of such a system is enhanced in one of two ways:. 

The temporal resolution of the extreme areas (noisy & over exposed) is equal to one camera, while the non-extreme areas--gooddata--are equal to the sum of both cameras. 

If the two cameras are setup for maximum spatial resolution--in the staggered pixel mode--then the spatial resolution of the two extreme areas (noisy & over exposed) is equal to one camera, and the non-extreme areas--when combined--are equal to the sum of both cameras ( i.e., resolution = X2).
 


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[1]Remember:
Electronic Exposure Control of CCD or CCD type arrays is a matter of controlling the number of photoelectrons that are allowed to accumulate in the wells of what constitutes the "photo-sites." 

This is done by periodically dumping excess photo-electrons from the "wells" before they fill and overflow, and cause blooming. 

This dumping continues until transfer time occurs: This is where all of the accumulated photoelectrons remaining, are "dropped thru" to the waiting analog bins below, and are then shifted out--pixel by pixel--as raw video. 

The above can be thought of as normal exposure to over exposure. In the case of under exposure, the integration time is extended beyond the normal transfer interval (e.g., 1/60 sec) i.e., dumping is held off beyond the normal readout time, or frame transfer time (one frame time). 

Of course, for extended exposure time: frame time can be extended to some multiple of normal frame time (e.g, 1/60 sec) by buffering previous images and allowing longer integration time

1) Thermo Electric Cooler
TEC cooling for improved S/N ratio--for every ~6 degrees C reduction: a doubling of S/N ratio, or one bit is added to the dynamic range.
2) Sequential Color:
Color wheel, Sequential Electric LCD Filters --Red, Green, Blue; Clear, Yellow, Cyan; etc.
Vibration Heat/Cold extremes G-forces, shock from large ordinance: in situ or local detonation, incoming impacting round(s).
"Relay Lens Arrangement for Image Sharing with Multiple CCD Arrays."

Short Explanation:
The relay lens(s) captures the focusing/converging image light (cone of confusion) from the taking lens before it converges or focuses on the focal plane, and collimates it (stops the converging process). The beamsplitters (cemented prisms) steal some percentage of the image light and allows the remaining light to pass undistorted, to the next beamsplitter, and so on. 

By the proper selection of the beamsplitter's transmission/reflection ratio, equal amounts of image light go to each of the finite number of CCD array sensors.



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Video Encoding/Adaptive Gain Ranging





Hemispherical Mirror

Cone Mirror
Hemispherical Mirror ---- Conical Mirror (45deg.) ----  Hyperbolic Mirror ----  Shallow Conical Mirror
Mirrored Optics for 360 degree Coverage
Derived Mirror Curvature


Sensor
Survey
Table 1
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I'll Never finish  this Damn thing!
Copyright 1999 - 2015  Web Author: Glen A. Williamson  webmaster
    Scratch Pad Area
    ____________________________________________

    T h r e a t s 

Intentional:

LASER Blinding

Sun Light/Reflections/Glare

Not enough light

Are all WLs needed, can some bands of light be eliminated (notched out)

Are there Optical Communications WLs that the system needs to be Immune from??

Environmental:
The mechanisms that can cause the most grief:
1) Alignment of all of the optical elements! (goes without saying--but I said it!)

2) Focus of the relay lens, i.e., where the front relay lens intercepts the primary image cone of light. This will determine whether any residual divergence or convergence exist over the distance to the secondary relay lenses (CCD end), and ultimately the focal planes of all of the CCD arrays.

That is to say, image registration and the magnification factor (mag = 1.00) will be the same for all arrays if this parameter is correct.

Fixes for any errors:
Some of this can be compensated for--within reason--by the computer, registration being the main one that comes to mind.

more later...