The Future of NVIS Display Measurement

1
The Future of NVIS Display Measurement

• Dr. Richard Young
• Optronic Laboratories, Inc.

2
Introduction
Thanks to the excellent quality of modern
scanning instruments, NVIS compatibility
measurements have become almost routine.
What improvements could instrument manufacturers
make
3
Introduction
A wish-list for improvements

• Better sensitivity, so low luminance small spot
  sizes can be measured as easily as high luminance
  large spot sizes.
• Less variation in results
• Faster scans
• Greater portability and ruggedness
• Lower cost

4
Sensitivity and Variability
Scanning systems have plenty of sensitivity
Much of the variability is due to the longer
wavelengths
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Sensitivity and Variability
The OL 770-NVS detector is based on silicon, and
hence has a different shape,
There is no dramatic change in longer wavelength
sensitivity
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Spectroradiometer design
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Spectroradiometer design
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Spectroradiometer design
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The Multiplex Advantage
The multiplex advantage means that an instrument
simultaneously measuring a signal over a range of
frequencies obtains a t1/2 advantage in the time
t required to obtain a given signal-to-noise
ratio compared to that which would be necessary
using dispersive methods if the noise is
detector-limited. http//scienceworld.wolfram.c
om/physics/MultiplexAdvantage.html

• When all the light is seen all the time
• Noise is decreased.
• Sensitivity is increased.
• Measurements can be faster.

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Spectroradiometer design

• The OL 770-NVS is a special type of
  spectroradiometer, many decades better than other
  multi-channel devices.
• Far higher sensitivity
• Much lower noise
• Orders of magnitude lower stray light
• Vastly improved electronics
• Dedicated software
• State-of-the-art technology

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MIL Spec Others

• A.3.3. Wavelength accuracy repeatability
• Accuracy typical lt0.5 nm, spec. 1 nm
• Repeatability typical lt0.01 nm, spec. 0.5 nm
• A.3.4. Current Resolution
• 16 bit, spec. 12 bit.
• A.3.5. Zero Drift
• Typical lt0.01, spec. 0.2

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MIL Spec Others

• A.3.6. Linearity
• In scale lt0.5, spec. 1
• Between scales lt0.1, spec. 2
• A.3.7. Signal Conditioning
• Required controls for improving s/n provided
• A.3.8. Stray light
• Passes easily

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MIL Spec Others

• A.3.9. Spectroradiometer Optics
• Full scale at lt0.1 fL, spec. 1 fL (at 0.007 spot
  size)
• A.3.10. Spectroradiometer Viewing System
• Exact, spec. lt5 of spot diameter
• A.3.11. Spectroradiometer Accuracy
• Typically lt 1, spec. 5
• Typically uv lt0.0003, spec. 0.007

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Other Advantages

• Since there are no moving parts
• the construction is rugged and compact
• results are highly repeatable
• time taken in moving the monochromator, changing
  filters etc. is avoided

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Other Advantages

• Since there is no photomultiplier
• A very expensive component is avoided
• The detector is not damaged by strong light
• High voltages are not required
• Since all the wavelengths are measured at the
  same time
• It doesnt matter if the source is d.c., a.c.,
  modulated or flashed

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An Intercomparison Study
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An Intercomparison Study
Green B
NVIS Red
NVIS Yellow
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An Intercomparison Study
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An Intercomparison Study
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An Intercomparison Study
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An Intercomparison Study
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NVIS Green B Results
For lt1 second scan
For 1-2 minute scan
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NVIS Green B Results
For 2 minute scan
For lt1 second scan
For 1-2 minute scan
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NVIS Green B Results
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NVIS Red Results
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NVIS Red Results
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NVIS Yellow Results
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NVIS Yellow Results
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Study Conclusions

• All systems gave extremely good repeatability in
  NRa, NRb and chromaticity.
• All systems gave the same results with very low
  uncertainties.
• All systems showed that NRa and NRb were
  essentially constant across a wide luminance
  range for each display.
• All systems showed chromaticity was essentially
  constant with luminance for each display.

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General Conclusions

• Developments over the past year have made it
  possible to design a new type of system for NVIS
  display measurements.
• This new type of system represents a quantum leap
  in performance and value.
• All the wish-list items are fulfilled.