RetrieverTech

   an advanced digital imaging company

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RetrieverTech offers a unique shuttering solution that is perfectly suited for our super fast FC-Series cameras or application where fast shuttering is critical.   The challenges in shuttering a large format imager, at short exposure times, with long MTBF (mean time before failure), while preserving a wide dynamic range and MTF (modulation transfer function) are all met with the PSCT shutter.

  Advantages of the RT-PSCT Shutter

 The RT-PSCT shutter’s unique light scattering behavior has distinct advantages for high speed, large format imaging.  

 Ö Advantage

All polarization information is retained.    No polarizers are used in shutter construction, allowing crucial polarization information to be retained

 Ö Advantage

Extremely long MTBF.   RT-PSCT shutters and drivers have been tested at > 10,000,000 cycles and show no signs of degradation.

Ö Advantage

MTF information is preserved.    Because of the unique scattering nature of the RT-PSCT shutter, all light transmitted in the OFF state is completely defocused and therefore adds no spatial content to the image.   Only a small bias is added to the image, which is easily subtracted.

Ö Advantage

The graph below shows the effect in dynamic range reduction as a function of transmitted light.   Even at 30% transmission, the dynamic range is only reduced by a few dB.  This leads to high quality image with high MTF preservation, owing to the completely defocused nature of the transmitted light.   Standard LC shutters often times lose their performance at short exposure times of real scene information, particularly when the exposure time is short with respect to readout time.   It is in these situations that the RT-PSCT shutter is the optimum choice.

  How PSCT Shutters Operate

 PSCT shutters operate in a fashion similar to other LC (liquid crystal) shutters, but with key defining differences.   When the shutter is off, the polymeric dispersion is aligned within polydomains that weakly scatter light (Fig A).

FIG. A

  The application of an electric field aligns the dispersoids, nearly instantaneously, into a light transmitting orientation (Fig B). 

FIG. B

This scattering of the light results in a small residual bias applied to the sensing device during readout, but because the light is completely defocused, no scene information is transmitted, allowing the preservation of high MTF and minimal reductions in dynamic range.

The switching speed is a function of applied voltage and operating temperature.   For typical operating conditions, RT-PSCT shutters switch in less than 500 microseconds (Fig. C). 

FIG. C

  RT-PSCT shutter specifications

The RT-S-PSCT-50 is designed to interface with standard Schneider Optics Macro©  systems, as well as systems previously designed for Vincent shutters.   Please contact RetrieverTech for details.