While most of us are limited to the visible spectrum, people with a condition called aphakia possess ultraviolet vision. Aphakia is the lack of a lens, due to surgical removal for cataracts or congenital defects.
A railroad lantern and a railroad lamp are two different things. Lanterns were designed to be portable (i.e. carried) and were basically globes surrounded by a metal frame with a fuel source. When you think of a railroad worker swinging a signal, think lantern.
Canted ironsights are an accessory rail attachment featured in Battlefield 4. As the same rail is used for lights and laser sights, the Toggle flashlight button is used to switch between the top-mounted optic and these ironsights.