UV Light


Ultraviolet light is also known as ultraviolet radiation. It is a form of energy which is a part of the electromagnetic spectrum. It is a form of non-ionizing radiation.

Ultraviolet (UV) is a 10 nm to 400 nm wavelength electromagnetic radiation.

It is shorter than visible light (ranges from 400 nm to 700 nm) and longer than X-rays (ranges from 0.01nm to 10 nm).

Wavelength of Ultraviolet region:

The ultraviolet wave of the spectrum has been divided into three regions:

Image Of UV Lamp taken by Archana Singh

1. Short wavelength: It ranges from 180 to 280 nm.

UV light of short wavelength is used in Following types of work: Photochemical reactions, Sterilization, Chromatography, Mineralogy, and, etc.

2. Medium wavelength: It ranges from 280 nm to 320 nm. A quartz lens is essential for this wave transmission. Sun lamps are artificial sources for this type of radiation.

UV light in Medium wavelength is also used for cosmetic and therapeutic purposes;

3. Long wavelength: It is also known as near ultraviolet and ranges from 320 nm to 400 nm. It is produced by portable lamps and very beneficial in forensic science field to the forensic experts for document examinations.

Source of UV Light:

This radiation is produced by natural sources, such as the sun and it most common source to produce uv light. It contributes about 10% of the Sun’s overall electromagnetic radiation production. It is also generated by specialized arcs and lights such as mercury-vapor lamps, tanning lamps, black lights, electronic flashes, halogen, fluorescent, and incandescent lights, lasers, etc. and, it is often together with visible light.

The most common form of UV radiation is sunlight, which produces three main types of UV rays:

  • UVA.
  • UVB.
  • UVC.

UVA rays have the longest wavelengths, followed by UVB, and UVC rays which have the shortest wavelengths

Use of UV Rays in Forensic Science:

UV radiation is commonly used in manufacturing procedures and in medical and dental activities for a number of uses, such as destroying bacteria, producing fluorescent results, curing inks and resins, phototherapy and sun tanning. There are various UV wavelengths and frequencies used for various purposes.

Ultraviolet (UV) rays or illumination techniques are used for various types of purposes in forensic science examinations. With the help of UV rays forensic experts are able to get the identify that if the specimen is genuine or forged as it is widely used in Questioned document examination, and to get the latent prints and many more works, For example:

  • Latent fingerprints examination,
  • In Identification of body fluid at crime scene or on clothes.
  • Forged Signatures,
  • Documents in question,
  • Ink examination,
  • In detection of ink stains, and,
  • Duplicate Paintings, etc.
Image taken in UV light by Archana SIngh