Physicians and repair engineers often use small light pens for visual examination Spurposes. Rugged and expensive as these pens may be, their weak point is the bulb, which is a ‘serviceable’ part. In ...

If you worked with computers back in the 1970s, there’s a good chance you used a light pen at some point: a simple input device that you’d point at the CRT screen to highlight text, choose menu ...