Monday, July 9, 2012

Important Facts

Rohit Dhyani: Electromagnetic spectrum: This spectrum depicts light as a wave of radiation, which has both a peak height (amplitude) and a distance between peaks (wavelength).


Fluorescence: A stimulating light, usually from a laser or alternate light source, is directed onto a surface. Molecules in the surface will become excited, and some of their electrons will rise to a higher electronic state. As they return to their previous state, energy is emitted. The light subsequently emitted has a lower intensity than the original stimulating light. Light of a different wavelength and frequency also has a different color.

Infrared light: The photographic area of the infrared (IR) range is in the near IR part of the electromagnetic spectrum, 700 to 1100 nm.
Luminescence: A molecule’s ability to “glow” from causes other than heat, and luminescence and phosphorescence are both types of luminescence.
Phosphorescence: The ability of some materials to retain some of the radiation they have absorbed after the stimulating light has ceased. This energy can then be released over long durations: “glow in the dark” toys are an example.
Photographic infrared range: The range on the electromagnetic spectrum between approximately 700 and 1100 nm.
Prioritizing perishables: Some evidence may remain at the scene for long periods and still retain its full value as evidence. Other types of evidence are fleeting or highly perishable and need to either be collected as soon as possible or protected to avoid loss or change.
Refraction: When light changes from one medium to another, it will bend. Viewing underwater objects will be affected by refraction. The result is that objects underwater appear approximately 25% closer to the viewer than they really are.
Ultraviolet light: The region on the electromagnetic spectrum between 100 and 400 nm. It is also sometimes divided into long, medium, and short wave ultraviolet light (UV). At times, it is thought of as UVA, UVB, or UVC.
Visible light: The range on the electromagnetic spectrum between 400 and 700 nanometers (nm). A nanometer is one billionth of a meter.