"Vampir" ZG 1229 on StG 44 assault rifle (Sturmgewehr)

Specific Features:
The Vampir was not the first German Infrared System, but by the end of the war in 1945 it was the most compact and advanced system they had. The technology itself dates back to around the start of the war, when engineers developed the first infrared rangefinder for German light anti-tank artillery.
This was improved and some heavier direct-fire artillery was equipped with it as well. By 1944 the Germans had developed a version flexible enough to be mounted on the Panther tank (Germany's most technologically advanced and complex tank) and by the last year of the war were ready to issue the man-portable Vampir system.

The Vampir system consisted of a "black" spot light, one component of its active infrared system, fixed atop the impressive StG-44 assault rifle. Below this infrared light was a range finder that could detect the light emitted by the IR lamp.
Since this light was invisible to anyone not equipped with the system it gave a massive edge over relying on flashlights and flares for illumination.
The system mounted on the gun was linked by insulated wire to a heavy battery pack and simple control box that the soldier wore in place of his normal gear’  a very crude analog to today's "OICW" system being developed by the United States.
It could transform a normal soldier it one capable of fighting in complete darkness, be it a cave or a moonless night, without revealing his position.

There is dispute over whether or not the Vampir was actually issued to combat soldiers.
Some reports claim it was given to special units of the Waffen-SS for testing, others claim it was issued to crews of the similarly equipped Panther. Probably that what few units were combat-ready were probably issued to the ultra-elite commandos of commanders like Otto Skorzeny and perhaps in the final defense of Berlin.
Chances are we will never know the exact truth as no photographs exist of troops utilizing the weapons in the field, but the system was proven to work.

History: Of all the wacky German inventions of World War II, both failed and successful, none had a bigger effect on the state of modern warfare than the Vampir IR system and its variants.
Few people really consider the relative level of optics technology at the time of the war, but today our lives revolve around staring at screens and let's not forget that TV got its start with a broadcast of Hitler. The German's did all kinds of really dumb and worthless experiments with optics and sensors like trying to send infrared beams through the poles to view the opposite side of the earth.
In fact they were behind the British in radar technology, a gap that they paid heavily for during the bombing campaign over England. Infrared technology paid off though, and even if it was never deployed in massive quantities for the troops who used it the technology made a difference.
Today almost every military combat vehicle is equipped with some variant of infrared optic and large numbers of American infantry are as well. Police helicopters and even consumer video cameras are outfitted with the technology, all thanks to some pioneering Nazis.

well....I wouldn't be so sure of myself to use it in daylight...

yep, FAL was also standard in the Belgian army. My brother used it in his days.