Patent ID: 8860831

Claim:
An optical device comprising: a first imager for viewing a target of interest and providing a first output image to a viewer, a second imager for viewing the target of interest and providing an output signal, a display for receiving the output signal and providing a second image to the viewer, a beam splitter positioned to receive the first and second images and transmit the first and second images to the viewer, and a photodiode circuit positioned adjacent the beam splitter for measuring brightness levels of the first output image, and providing the brightness levels to the second imager, a blanking circuit providing a trigger for starting a blanking interval on the display, wherein the photodiode circuit is configured to receive the trigger and start measuring the brightness levels of the first output image in synchronism to the blanking interval on the display, wherein the second imager receives the brightness levels and, in response, controls intensity levels of the second image.