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Configured as Pyramid Wavefront Sensor
Little Joe cameras are very versatile and can be programmed in many ways. For use as a Pyramid Wavefront Sensor, the camera is usually programmed with alignment and 2x2 binning modes. The user can upload and run 3x3, 4x4 and 5x5 binning modes on demand as dictated by conditions.

 

Optimized for High speed and Best SNR

Little Joe cameras are specialized to run scientific CCDs at their maximum speed with the highest possible Signal to Noise Ratio (SNR). At the lowest light levels, CCDs are limited by read noise and at the highest light levels, CCDs are limited by photon noise. Our back-thinned CCDs are selected to have the highest possible Quantum Efficiency (QE) for the wavelengths of interest. This yields the maximum photon-noise-limited SNR by maximizing the number of electrons produced by photons. Our CCDs are also selected to have the lowest possible readnoise to maximize SNR when read noise limited.

 

CCDs – better than EMCCDs and CMOS

EMCCDs offer low noise at low photon fluxes by using extremely high gain in their serial outputs, which leads to several problems.In high gain mode, EMCCDs suffer degradation in photon noise SNR due to the statistical processes used in the amplification process. This reduces the SNR by the square root of 2. These statistical processes also result in rogue multiplication events (spurious charge), leading to pixel spikes which when digitally eliminated in the camera can result in the elimination of real pixel spikes. The extremely high gain in the output depends on very high clock voltages in the camera. This leads to long-term damage to the sensor and the potential for gain instability.

CMOS sensors can offer low readnoise but have low QE since there is a light-mask over the electronic circuit contained in each pixel. Since the photons are not absorbed uniformly across the sensor, they are unsuitable for wavefront sensing. They also suffer from random noise spikes that are digitally eliminated in the camera and can result in real noise spikes being eliminated. Pixel lenslets can improve QE but make uniformity even worse.

Camera Specifications

 

CCD Controller
 

Desktop controller with integrated cooling fan includes the following modules:

 

  • 5-slot 3U backplane

  • Digital module – includes digital sequencer, flash memory, and CameraLink interface

  • Clock Driver module – drives CCD clocks

  • Service module – provides CCD biases, temperature control and readback

  • 4-Channel Input Module – digitizes CCD video signals. Incorporates 4 14-bit 10 MHz A/D converters

  • Spare slot for future expansion

  • Measures 9.625” x 5.625” x 6.0” (255 x 145 x 150 mm)

  • Weighs 7.5 lb (3.4 kg)

 

 
CCD Camera Head
 

Remote Camera Head includes the following features:

 

  • Remote from CCD Controller for digital noise immunity

  • Passive cooling - no fan vibration

  • Massive heatsink – easily coupled to thermal sink

  • Integrated Thermoelectric Cooler (TEC) minimizes power

  • Small Camera Head fits more easily on optical bench

  • 3m cable allows flexible positioning of Camera Head

  • ¼-20 mounting holes for secure mounting

  • Measures 4.5” x 4.5” x 3.5” (115 x 115 x 90 mm)

  • Weighs 3.0 lb (1.4 kg)

• 24 μm x 24 μm pixels 

• 80 x 80 pixel frame size

• Split frame for rapid image transfer

• Image transfer in 7 μs

• 4 ports for rapid image read out

• Integrated Thermoelectric Cooler

• Backthinned, Midband A/R coated for High QE:

> 25% @ 400 nm

 

> 60% @ 500 nm

 

> 85% @ 650 nm

 

> 45% @ 900 nm​​​​​​​​​​

 

 CCD39 Specifications
Pyramid wavefront sensor modes

 

Alignment modes:

 Rate(Hz) Format Binning RON(e-)

   1000   80x80    -      8.0

    400   80x80    -      5.2

    200   80x80    -      3.8

     80   80x80    -      3.7

 

Binning modes(2x2):

 Rate(Hz) Format Binning RON(e-)

   2000   40x40   2x2     8.5

   1250   40x40   2x2     5.8

    650   40x40   2x2     3.7

    275   40x40   2x2     3.0

 

Binning modes(3x3):

 Rate(Hz) Format Binning RON(e-)

   3400   28x26   3x3     9.0

   2000   28x26   3x3     5.4

   1100   28x26   3x3     3.8

    500   28x26   3x3     3.7

 

Binning modes(4x4):

 Rate(Hz) Format Binning RON(e-)

   4000   20x20   4x4     8.5

   2500   20x20   4x4     5.5

   1500   20x20   4x4     3.8

    725   20x20   4x4     3.8

 

Binning modes(5x5):

 Rate(Hz) Format Binning RON(e-)

   5000   16x16   5x5     8.5

   3000   16x16   5x5     5.7

   2000   16x16   5x5     3.7

   1000   16x16   5x5     3.8

 

Selectable Gains*

   0.5 ADU/e-

   1.6 ADU/e-

   3 ADU/e-

  11 ADU/e-

(*Nominal gains)

LITTLE JOE CCD39PS CAMERA

Pyramid Wavefront Sensor