Laser Messaging

On covert spy or military missions, yelling to companions is often out of the question, and radios can be picked up on. pigeons can be shot down, the tin cans with string are too conspicuous, fax machines are unweildy, messages written on paper airplanes can be difficult to aim and easy to intercept and bird noises are not always appropriate, as there may or may not be birds in the area.

Take a non-this-incinerates-stuff laser that illuminates an area about the size of a quarter, and make a series of slides to go over the end. different symbols can mean "go back" or "my platoon has been shot" or "there is a horde of huns on elephants behind you". Then, if you can see your contact, from however far away, you can send them a message. receivers could carry table tennis paddle type things for easier veiwing. Morse code could be used. This would be more covert than just using a flashlight, because the laser will only shine on an area the size of a quarter, and the initial light will be harder to see. Not recommended for steamy/smoky locales.