Discuss the production of Infra-Red Radiation. Describe the Therapeutic effects and danger of Infra-Red Radiation

Discuss the production of Infra-Red Radiation. Describe the Therapeutic effects and danger of Infra-Red Radiation.
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Introduction
The infrared rays are electromagnetic waves with the wavelengths of 750 to 400000 nm and frequency 4 × 1014 Hz and 7.5 × 1011 Hz. It lies beyond the red boundary of visible spectrum. Any hot body can produce infrared rays like the sun, electric bulb, coal fire, gas fire, etc.
Production of Infra red radiation 
The infrared rays are produced by two types of generators:
1. Nonluminous generators
2. Luminous generators
Nonluminous generators provide infrared rays only whereas luminous generators emit infrared rays, visible as well as ultraviolet rays.
Nonluminous Generators
Nonluminous generator consists of a simple type of element or coil wound on a cylinder of  insulating material such as fireclay or porcelain. An electric current is passed through the wire which results in the production of heat. This heat produces infrared rays which are transmitted through the porcelain. Porcelain gets heated by the method of conduction but the radiations generated in this way also include some of the visible rays. Therefore to avoid this, the coil is embedded in fireclay or porcelain or placed behind fireclay. Now the emission of rays is entirely from the fireclay which is commonly painted black and thus very few visible rays are produced. The element or the coil is thus placed at the focal point of a parabolic or spherical reflector. The reflector is mounted on a stand and its position can be adjusted as required.
In another type of nonluminous generator, a steel tube within which an electric coil is embedded on some material which is electric insulator but good conductor of heat is used. Electric current is passed through the central coil and thus heat is produced. The steel tube thus emits infrared rays.
All of these nonluminous generators take some time to get heated up for the production of infrared radiations, so they should be switched on before 5–7 minutes of the treatment.
Luminous Generators
Luminous generators emit infrared, visible and a few ultraviolet rays. These generators are in the form of incandescent lamps or bulbs. An incandescent lamp consists of a wire filament enclosed in a glass bulb, which may contain an inert gas at low pressure. The filament is a coil of fine wire which is usually made up of tungsten. Tungsten is a metal which is used because it can tolerate repeated heating and cooling. The exclusion of air prevents oxidation of the filament, which would cause an opaque deposit to form on the inside of the bulb. Incandescent bulb is usually mounted at the center of the parabolic reflector and the reflector is mounted on an adjustable stand. These luminous generators emit the electromagnetic waves with the wavelength in between 350 and 4000 nm, the maximum proportion of the rays having wavelength in the region of 1000 nm. The front of the bulb is usually red so as to filter out the shorter visible and the ultraviolet rays.
 
Therapeutic Effects of Infra-Red Radiation
Pain Relief: Infrared radiations are effective in relieving pain. Mild heating on the superficial tissues by infrared radiations causes sedative effects on the superficial sensory nerve endings. Pain may be due to accumulation of waste products of metabolism, an increased flow of blood through the part removes these substances and thus relieves the pain.
The pain due to acute inflammation or recent injury is relieved most effectively by mild heating. When pain is due to chronic injury or inflammation, stronger heating is required. The treatment may last up to 30 minutes.
Muscle Relaxation: Relaxation of muscles is achieved by heating the tissues. Mild heating by infrared causes relaxation of muscles and thus relieves spasm. Relief of pain also induces relaxation in muscles and helps relieving muscle spasm associated with injury or inflammation. 
On Blood Supply: Infrared radiations increase the temperature in the superficial tissues, causing vasodilatation in the superficial tissues. It also accelerates removal of waste products and helps bring about resolution of inflammation. It is most beneficial in the treatment of various arthritic conditions of joints which leads to inflammation and stiffness. Cases of post immobilization stiffness, open wound and infections can also be effectively treated.
Dangers of Infrared Radiations
1. Burn: Excessive heating of superficial tissues causes burn. Sensation must be checked before starting the treatment. If sensation is not proper, the patient may not appreciate the extent of heating. The patient must be warned to inform undue heating immediately. 
2. Electric shock: Electric shock can occur if some exposed part of the circuit is touched by the patient. Due to heating of the wires in the circuit, insulation of wires may go off and thus regular checking of wires is necessary to avoid electric shock.
3. Faintness or giddiness: Extensive irradiation may cause fall in blood pressure which may result in faintness or giddiness due to hypoxia of the brain. This is particularly common when the patient rises up suddenly from the recumbent position after extensive treatment.
4. Headache: Irradiation of the back of the head may cause headache. Headache may also occur when treatment is given during hot weather. Lots of fluid goes off the body in the form of sweating during treatment. Plenty of water needs to be replenished during or after the treatment especially in hot weather.
5. Gangrene: Gangrene may be caused in the areas of defective arterial blood supply following prolonged irradiation by infrared radiation. Arterial supply to the area being treated needs to be proper to avoid gangrene.
6. Injury to the eyes: Direct heating over the eyes causes drying up and thus leads to corneal or retinal burns. Eyes needs to be protected following treatment to avoid injury.