LUMITRONICS

 

SELECTIVE GLARE REDUCTION OCULAR (SGRO)

 

 

 

DETAILS:  SELECTIVE GLARE REDUCTION OCULAR PROTOTYPE

 

   The SGRO is a small, patented, electro-optic, broad-band ocular for attenuating very bright lights in observed scenery.  This real-time device relays actual, attenuated image light from objects but attenuates the brightest objects to a much greater extent.  A useful measure is the Differential Relative Bright Transmittance (DRBT).  The DRBT indicates that the visible light component above a nonlinear threshold for a given source is effectively attenuated to a transmittance of only 13 - 27 % of that below.  (More attenuation if narrow band imagery is desired.)  Lumping attenuated and unattenuated components of a bright light source together expresses the simpler Relative Bright Transmittance (RBT) which is nominally 26 - 33 % of that for dim and normally illuminated sources.  The SGRO is not a camera/display unit and contains no resolution-limiting pixel structure.  With its internal, electrically powered, Nonlinear Attenuator Device (NAD), the SGRO is a light dynamic range compressor.  However, scenery of dim and normal brightness is virtually unaffected in color and linearity. 

 

  Any light source containing deep red and near infrared light (660 - 760 nm) will enable the NAD functionality.  Though little of this emission is actually seen through the ocular, it exists in incandescent lights, sunlight and welding arcs, and thus the NAD contributes to attenuating the annoyingly bright visible components of such sources.

 

  Theoretically, if light is bright enough, the attenuated transmittance will begin to increase somewhat again.  However, sensitivity to a further rise in intensity decreases for high intensities, and the reduced transmittance is virtually unchanged for orders of magnitude in some cases.  In this broad higher intensity attenuation range, there may be a small intensity-dependent color shift from bluish to yellowish or vice versa, depending on the choice of certain components.  For uses in electronic cameras, or any photography with post processing, this color change is correctable by using data from simple measurements on the scene made by sensors attached to or within the SGRO.  If intent is to reduce glare so attention can be focused on normally illuminated content, the slight color gradation presents no problem and may even be considered interesting and thereby avail itself to special effects.

 

  If the SGRO is attached to the head or held to the eye (or camera), normal movement of the head/ocular unit will not cause noticeable streak or flashing from latency of the NAD because operating parameters insure a sufficiently rapid response time.

 

   Although square wave power of 6-11 Vac from a waveform generator was used for the specifications, the SGRO will operate with sinusoidal ac power.  Current requirements given in the specifications are low and yet very conservative,  being made for a larger NAD than in the actual prototype.  A small power supply (with batteries) attached to the person by a Velcro strap is possible.

 

  Specifications listed are for the limited-budget prototype and do not bound the value attainable with manufacturing development.  In fact, low intensity transmittance could be improved for a simple version using a camera for which image orientation is corrected in post processing. A second NAD with consequent higher cost could also improve low intensity transmittance.

 

DISCUSSING APPLICATIONS:

 

   Possible applications abound in industry, search and rescue, photography and cinema, surveillance and other activities performed in bright glare.  Imagine looking for objects or persons in crevasses surrounded by blinding white snow, needing to see nearby task objects but having visual protection when welding or working with arcs, peering at bright vats of molten steel, driving against the pre-setting sun, photography or cinematography scenes against the sun, inspecting electric lights and EVA servicing of space hardware where light contrast is extreme.  Because of tremendous gain in MCP night vision gear, the SGRO can be useful against dazzling washout due to occasional search lights, flares, etc.  With a simpler up-front construction and two NADs per ocular, transmittance of low-level light can be increased even more while still attenuating brighter sources.  A binocular application of two SGROs is obvious, but a non-stereographic construction for both eyes with one SGRO is also an option.

 

   You are invited to inquire, inform and discuss applications, markets and required volume with us concerning the SGRO.

 

PROTOTYPE SPECIFICATIONS (BRIEF VERSION)⁽¹⁾

1)  Values for prototype are not limits for more fully developed SGRO.  Exact values not assured; may change.

2)  Less intensity for lower power frequency, higher for high frequency.

3)  Rise ~ 10% to 90%, decay 90% to 10%.  Sum of rise and fall is the best response indicator.  Specific parameter adjustments determine whether rise or fall time is greater.

 

Copyright ã 2002 James Lynn Smith. All rights reserved for drawings, photos and text.