Phosphor coated NIR Cameras

 Phosphor coated NIR Cameras

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Phosphor Coated NIR Cameras
Features
  • 1440-1605 nm Wavelengths
  • NIR Telecom mode field analysis
  • NIR Laser beam analysis
Available Models
  • USB models: SP503U-1550
    •           SP620U-1550
  • Firewire models: GRAS20-1550
  • Analog Camera*: SP-1550M
* When used with beam profiling software, requires LBA-PC-10 framer grabber system (sold separately) 1610nm OPO Output 1550nm Fiber Output
 
Phosphor Coating Technology
The up-conversion from NIR to visible light in the 1550 series cameras is nonlinear. The anti-Stokes phosphor coating produces visible photons at a rate roughly the square of the input signal. This is shown dramatically where the camera total output increases dramatically faster than a linear output shown in the bottom line. The CCD camera saturation in the center of a beam, the up-converted visible signal drops as the square of the input signal. Thus the lower signal wings of a beam are suppressed, resulting in the appearance and measurement of a beam width much smaller than actual. This illustration a comparison of the cross-section of a beam with and without correction. (As seen, the real width of the beam is much greater than would be observed without correction.
 
Non-linear output of the 1550 series cameras. Cross-section of a fiber beam with and without non-linearity correction.
Wavelength Response
The anti-Stokes up-conversion efficiency is very wavelength dependent. This graph shows the typical spectral response curve of a new, high response coating. As seen, we have calibrated the response from 1527nm to 1605nm. We have extrapolated the shorter wavelength region by comparing our measured response to data published over the entire range.
  Signal required versus wavelength to achieve camera full signal illumination by anti-Stokes up conversion material.
 
Phosphor Coated Cameras with Spiricon's BeamGage and LBA software
Spiricon engineers have carefully measured the non-linearity of the signal generated by the Phosphor Coated series cameras. The software in the LBA Beam Analyzers incorporates an algorithm to correct for the non-linearity. This illustration shows the linearity obtained, showing in the top line that the low level signals drop linearly, rather than at the square of the input, seen in the lower line.
The two photos show the uncorrected and corrected camera beam shape in 3D. See the LBA section for additional information on the beam analyzer.
 
Beam profile of a fiber beam with non-linearity correction. Beam profile of a fiber beam without non-linearity correction.
 
SP-1550M; RS-170 monitor display when used without a frame grabber
Phosphor Coated NIR Cameras
Item Specification
Camera USB SP503U-1550 USB SP620U-1550 GRAS20-1550 SP-1550M
Application: NIR wavelengths,½" format, low resolution NIR wavelengths, 1/1.8" format, low resolution, adjustable ROI and binning NIR wavelengths, 1/1.8" format, adjustable ROI NIR wavelengths, 1/2" format
Spectral Response: 1440 - 1605nm 1440 - 1605nm 1440 - 1605nm 1440 - 1605nm
Maximum beam size 6.3mm W x 4.7mm H 7.1mm W x 5.4mm H 7.1mm x 5.4mm 4.7mm x 5.4mm
Pixel spacing(1) 9.9µm x 9.9µm 4.4µm x 4.4µm 4.4µm x 4.4µm 8.4µm x 9.8µm
Number of effective pixels 640 x 480 1600 x 1200 1600 x 1200 640 x 480 pixels
Minimum system dynamic range(2) ~30 dB ~30 dB 30 dB 30 dB
Linearity with Power ±5% ±5% ±5% ±5%
Spatial Uniformity ±5% ±5% ±5% ±5%
Accuracy of beam width ±5% for beams larger than 0.6 mm
Frame rates(3)
In 12 bit mode		 50 fps at full resolution, 80 fps at 320x240 7.5 fps at full resolution, 28 fps at 640x480 15Hz full res >60Hz with smaller ROI(3) 30 Hz
Shutter duration 10µs to multiple frame times 1/60 to 1/100,000 sec, 9 steps
Gain control 43:1 manual 29:1 manual 0db to 25db Manual control Manual adjustment
Trigger Supports both Trigger In and Strobe Out. N/A
Photodiode trigger Consult Factory N/A (consult factory) N/A
Saturation intensity 7mW/cm2 at 1550 nm
Lowest measurable signal ~ 50µW/cm2
Damage threshold 50W/cm2/0.1J/cm2 with all filters installed for <100ns pulse width(4) 0.15 mW/cm2 0.15 mW/cm2
Dimensions and CCD recess 89mm x 89mm x 28mm CCD recess: 4.5mm below surface 20mm x 44mm x 58mm Fixed C-mount 37mm x 34mm x 56mm CCD recess from surface 12.5mm, Adjustable
Operation mode Interline transfer progressive scan CCD Interline transfer progressive scan CCD Interline Transfer interlaced CCD
Software supported BeamGage and LBA LBA LBA-PC only
PC interface USB 2.0 IEEE 1394b GRAS20 RS-170 Framegrabber
Minimum host system requirements Pentium IV 1GHz (Dual-core & >2GHz for best performance), 1GB Memory, USB2, Operating system: Windows XP Pro, Vista-32 Pentium-4 1.7GHz (Dual-core & >2GHz for best performance), 1 GB Memory, IEEE 1394 Interface Requires PCI, IEEE 1394b requires PCI-Express, or CardBus Slot. Operating system: Windows XP Pro or Vista-32
  1. Despite the small pixel size, the spatial resolution will not exceed 50µm due to diffusion of the light by the phosphor coating.
  2. Signal to noise ratio is degraded due to the gamma of the phosphor's response. Averaging or summing of up to 256 frames improves dynamic range by up to 16x = +24dB
  3. In normal (non-shuttered) camera operation, the frame rate is the fastest rate at which the laser may pulse and the camera can still separate one pulse from the next. With electronic shutter operation, higher rate laser pulses can be split out by matching the laser repetition to the shutter speed.
  4. This is the damage threshold of the filter glass of the filters. Assuming all filters mounted with ND1 (red housing) filter in the front. Distortion of the beam may occur with average power densities as low as 5W/cm2
 
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