There are different types of IR illumination devices including LED light, laser type and filtered incandescent lamps.
These are high power lamps that are covered by an infrared filter. It lets the infrared radiation pass and blocks the visible light component. LED illuminators utilize a group of standard infrared emitting LEDs. The laser types are the most efficient among IR illuminators.
These devices are based on an infrared laser diode which produces near infrared energy.
The common light sources include LEDs and LASERs. Eye-safe, output power, covering angle are the most important issues for considering. For infrared applications, I suggest Laser Devices DBAL-I2 for using in area 1000 m2.
What is the question?
May be the most high quality source is the laser source as it is a coherent light. It may be also monochromatic with very concentrated beams.
However, the use of hot wire to produce infra red light is a a very practical and efficient means according to the theory of blackbody radiation as the temperature of the filament decreases it will emit more infrared radiation.
So, this method may be an efficient infrared radiation with cost effective.It can also produce in rared with wavelengths not possible with laser diodes.
Best wishes