An infrared heater or heat lamp is a body with a higher temperature which transfers energy to a body with a lower temperature through electromagnetic radiation. Depending on the temperature of the emitting body, the wavelength of the peak of the infrared radiation ranges from 780 nm to 1 mm. No contact or medium between the two bodies is needed for the energy transfer. Infrared heaters can be operated in vacuum or atmosphere.
One classification of infrared heaters is by the wavelength bands of infrared emission.
Short wave or near infrared for the range from 780 nm to 1.4 μm, these emitters are also named bright because still some visible light is emitted;
Medium infrared for the range between 1.4 μm and 3 μm;
Far infrared or dark emitters for everything above 3 μm.