This method mitigates the motion blur introduced when a display, and/or the operator reading it, is undergoing vibration (e.g. during the launch phase of spaceflight). If both the operator and the display are undergoing vibration, their respective impulses need not be in phase. This mitigation occurs when the display is illuminated at a strobing rate that corresponds with the frequency of the vibration. This can be done either by strobing the ambient illumination in the environment (e.g., if the operator is reading a reflective surface display), or by strobing the display itself (e.g., strobing the LED backlighting of an electronic display).

The dominant frequency of the vibration that requires mitigation can be known in advance, measured in real time, or predicted with algorithms. That frequency (or a lower frequency multiplier) is then used to drive the strobing rate of the illumination source. For example, if the vibration frequency is 20 Hz, one could employ a strobe rate of 1, 2, 4, 5, 10, or 20 Hz, depending on which rate the operator finds the least intrusive. The strobed illumination source can be internal or external to the display. The strobe rate can be matched to the vibration frequency, or to a lower-order multiplier of the frequency.

Perceptual psychologists have long understood that strobed illumination can “freeze” moving objects in the visual field. This effect can be used for artistic effect, or for technical applications. Current technical applications include: (1) strobing to maintain a rotating marker in a “fixed” position (e.g. the mark on an automobile timing belt appears stationary when properly tuned with the strobe rate of the timing light); (2) illuminating vibrating machinery with a light strobing at a rate matched to the vibration frequency to measure the frequency of a repetitive motion (vibration); and (3) illuminating vibrating machinery with a light strobing at a rate matched to the vibration frequency to allow inspection of the now visually stationary machinery.

This work was done by Mary Kaiser, Bernard Adelstein, Brent Buetter, Albert Ahumada, and Robert McCann of Ames Research Center; and Mark Anderson of Perot Systems.

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NASA Tech Briefs Magazine

This article first appeared in the July, 2014 issue of NASA Tech Briefs Magazine.

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