A. The brightness of the screen is automatically adjusted in response to the brightness of the scene. Thus the screen dims down in low ambient light. Back in the early 1980s, a colleague by the name of Kent Nickerson further suggested I put a red gel over my wearable display screen. In this way, the screen can be run a little brighter than the ambient light without desensing vision, which would otherwise require a short time period to return to full sensitivity. This suggestion was based on his belief that the eye's AGC was based on a sampling in the middle region of the spectrum (e.g. green). A blue filter would of course make it harder to read the screen, since blue is difficult to focus on. Thus after much experimentation, I decided to use red in low light. With a colour screen this selection is automatic. With Laser EyeTap, which is usually red already, the gel is not needed.

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