Polilight

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The Polilight is a portable, high-intensity, filtered light source used by forensic scientists and others to detect fingerprints, bodily fluids and other evidence from crime scenes and other places. [1]

Fingerprint biometric identifier

A fingerprint in its narrow sense is an impression left by the friction ridges of a human finger. The recovery of fingerprints from a crime scene is an important method of forensic science. Fingerprints are easily deposited on suitable surfaces by the natural secretions of sweat from the eccrine glands that are present in epidermal ridges. These are sometimes referred to as "Chanced Impressions".

Evidence Material supporting an assertion

Evidence, broadly construed, is anything presented in support of an assertion. This support may be strong or weak. The strongest type of evidence is that which provides direct proof of the truth of an assertion. At the other extreme is evidence that is merely consistent with an assertion but does not rule out other, contradictory assertions, as in circumstantial evidence.

Crime scene location that may be associated with a committed crime

A crime scene is any location that may be associated with a committed crime. Crime scenes contain physical evidence that is pertinent to a criminal investigation. This evidence is collected by crime scene investigators (CSIs) and Law enforcement. The location of a crime scene can be the place where the crime took place, or can be any area that contains evidence from the crime itself. Scenes are not only limited to a location, but can be any person, place, or object associated with the criminal behaviors that occurred.

Similar products to the Polilight Hola include the Foster + Freeman Crime-lite, Ultralite ALS and the Optimax Multilite, all of which use light-emitting diodes to produce high-intensity light of varying wavelengths.[ citation needed ]

The Crime-lite is a handheld, high-intensity alternative light source used primarily by forensic investigators to detect evidence such as fingerprints, bodily fluids and latent evidence from crime scenes.

Light-emitting diode semiconductor light source

A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. This effect is called electroluminescence. The color of the light is determined by the energy required for electrons to cross the band gap of the semiconductor. White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device.

History

The device was invented by Pierre Margot, Ron Warrener, Hilton Kobus, Milutin Stoilovic and Chris Lennard. It was developed from a research project to find an alternative to the laser method of fingerprint detection used in the 1970s. In the 1980s, the project began at the Australian National University. It was funded by the Australian Federal Police. The university's commercial company, Anutech Pty Ltd, sold the concept to Rofin Australia Pty Ltd, who developed it into the Polilight. [2] [3]

Pierre Margot is a Swiss forensics scientist known for his contribution to the invention of the first forensic light source Polilight for the detection of fingerprint, biological fluids and other evidence on the crime scene. This new technology was named by the Powerhouse Museum as one of the top 100 Australian innovations of the 20th century. It was a great revolution in the field of forensic identification since this light could be used at the crime scene, unlike lasers at that time.

Laser device which emits light via optical amplification

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term "laser" originated as an acronym for "Light Amplification by Stimulated Emission of Radiation". The first laser was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow.

Australian National University university in Canberra, Australia

The Australian National University (ANU) is a national research university located in Canberra, the capital of Australia. Its main campus in Acton encompasses seven teaching and research colleges, in addition to several national academies and institutes.

Several Polilight models have been released, including the Polilight 6/150W, Polilight 10/300W and the Polilight500, sometimes abbreviated to PL6, PL10 and PL500. The PL500 ('500' refers to the power in watts of the xenon arc lamp) has eleven monochromatic bands, a ‘blank’ position that provides high intensity white light in the range from 380 to 650 nm and an optional infra-red output suitable for document examination.[ citation needed ]

The watt is a unit of power. In the International System of Units (SI) it is defined as a derived unit of 1 joule per second, and is used to quantify the rate of energy transfer. In dimensional analysis, power is described by .

Xenon Chemical element with atomic number 54

Xenon is a chemical element with symbol Xe and atomic number 54. It is a colorless, dense, odorless noble gas found in the Earth's atmosphere in trace amounts. Although generally unreactive, xenon can undergo a few chemical reactions such as the formation of xenon hexafluoroplatinate, the first noble gas compound to be synthesized.

The Polilight was named by the Powerhouse Museum as one of the top 100 Australian innovations of the 20th century. [3] Its worldwide use was acknowledged by the Australian Export Awards in 2005. [4]

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Electric light A device that produces light from electricity

An electric light is a device that produces visible light from electric current. It is the most common form of artificial lighting and is essential to modern society, providing interior lighting for buildings and exterior light for evening and nighttime activities. In technical usage, a replaceable component that produces light from electricity is called a lamp. Lamps are commonly called light bulbs; for example, the incandescent light bulb. Lamps usually have a base made of ceramic, metal, glass or plastic, which secures the lamp in the socket of a light fixture. The electrical connection to the socket may be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap.

Arc lamp a light created by electrical breakdown of gas

An arc lamp or arc light is a lamp that produces light by an electric arc. The carbon arc light, which consists of an arc between carbon electrodes in air, invented by Humphry Davy in the first decade of the 1800s, was the first practical electric light. It was widely used starting in the 1870s for street and large building lighting until it was superseded by the incandescent light in the early 20th century. It continued in use in more specialized applications where a high intensity point light source was needed, such as searchlights and movie projectors until after World War II. The carbon arc lamp is now obsolete for most of these purposes, but it is still used as a source of high intensity ultraviolet light.

Flashtube Incoherent light source

A flashtube, also called a flashlamp, is an electric arc lamp designed to produce extremely intense, incoherent, full-spectrum white light for very short durations. Flashtubes are made of a length of glass tubing with electrodes at either end and are filled with a gas that, when triggered, ionizes and conducts a high voltage pulse to produce the light. Flashtubes are used mostly for photographic purposes but are also employed in scientific, medical, industrial, and entertainment applications.

Digital Light Processing display device

Digital Light Processing (DLP) is a set of chipsets based on optical micro-electro-mechanical technology that uses a digital micromirror device. It was originally developed in 1987 by Larry Hornbeck of Texas Instruments. While the DLP imaging device was invented by Texas Instruments, the first DLP-based projector was introduced by Digital Projection Ltd in 1997. Digital Projection and Texas Instruments were both awarded Emmy Awards in 1998 for the DLP projector technology. DLP is used in a variety of display applications from traditional static displays to interactive displays and also non-traditional embedded applications including medical, security, and industrial uses.

Fluorescence spectroscopy type of electromagnetic spectroscopy

Fluorescence spectroscopy is a type of electromagnetic spectroscopy that analyzes fluorescence from a sample. It involves using a beam of light, usually ultraviolet light, that excites the electrons in molecules of certain compounds and causes them to emit light; typically, but not necessarily, visible light. A complementary technique is absorption spectroscopy. In the special case of single molecule fluorescence spectroscopy, intensity fluctuations from the emitted light are measured from either single fluorophores, or pairs of fluorophores.

Sodium-vapor lamp gas-discharge lamp that uses sodium in an excited state to produce light

A sodium-vapor lamp is a gas-discharge lamp that uses sodium in an excited state to produce light at a characteristic wavelength near 589 nm.

High-intensity discharge lamp

High-intensity discharge lamps are a type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. This tube is filled with noble gas and often also contains suitable metal or metal salts. The noble gas enables the arc's initial strike. Once the arc is started, it heats and evaporates the metallic admixture. Its presence in the arc plasma greatly increases the intensity of visible light produced by the arc for a given power input, as the metals have many emission spectral lines in the visible part of the spectrum. High-intensity discharge lamps are a type of arc lamp.

Fluorescence microscope

A fluorescence microscope is an optical microscope that uses fluorescence and phosphorescence instead of, or in addition to, scattering, reflection, and attenuation or absorption, to study the properties of organic or inorganic substances. "Fluorescence microscope" refers to any microscope that uses fluorescence to generate an image, whether it is a more simple set up like an epifluorescence microscope or a more complicated design such as a confocal microscope, which uses optical sectioning to get better resolution of the fluorescence image.

Metal-halide lamp

A metal-halide lamp is an electrical lamp that produces light by an electric arc through a gaseous mixture of vaporized mercury and metal halides. It is a type of high-intensity discharge (HID) gas discharge lamp. Developed in the 1960s, they are similar to mercury vapor lamps, but contain additional metal halide compounds in the quartz arc tube, which improve the efficiency and color rendition of the light. The most common metal halide compound used is sodium iodide. Once the arc tube reaches its running temperature, the sodium dissociates from the iodine, adding orange and reds to the lamp's spectrum from the sodium D line as the metal ionizes. As a result, metal-halide lamps have high luminous efficacy of around 75–100 lumens per watt, which is about twice that of mercury vapor lights and 3 to 5 times that of incandescent lights and produce an intense white light. Lamp life is 6,000 to 15,000 hours. As one of the most efficient sources of high CRI white light, metal halides as of 2005 were the fastest growing segment of the lighting industry. They are used for wide area overhead lighting of commercial, industrial, and public spaces, such as parking lots, sports arenas, factories, and retail stores, as well as residential security lighting and automotive headlamps.

Xenon arc lamp

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Gas-discharge lamp artificial light sources powered by ionized gas electric discharge

Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionized gas, a plasma. Typically, such lamps use a noble gas or a mixture of these gases. Some include additional substances, like mercury, sodium, and metal halides, which are vaporized during startup to become part of the gas mixture. In operation, some of the electrons are forced to leave the atoms of the gas near the anode by the electric field applied between the two electrodes, leaving these atoms positively ionized. The free electrons thus released flow onto the anode, while the cations thus formed are accelerated by the electric field and flow towards the cathode. Typically, after traveling a very short distance, the ions collide with neutral gas atoms, which transfer their electrons to the ions. The atoms, having lost an electron during the collisions, ionize and speed toward the cathode while the ions, having gained an electron during the collisions, return to a lower energy state while releasing energy in the form of photons. Light of a characteristic frequency is thus emitted. In this way, electrons are relayed through the gas from the cathode to the anode. The color of the light produced depends on the emission spectra of the atoms making up the gas, as well as the pressure of the gas, current density, and other variables. Gas discharge lamps can produce a wide range of colors. Some lamps produce ultraviolet radiation which is converted to visible light by a fluorescent coating on the inside of the lamp's glass surface. The fluorescent lamp is perhaps the best known gas-discharge lamp.

Laser pumping Powering mechanism for lasers

Laser pumping is the act of energy transfer from an external source into the gain medium of a laser. The energy is absorbed in the medium, producing excited states in its atoms. When the number of particles in one excited state exceeds the number of particles in the ground state or a less-excited state, population inversion is achieved. In this condition, the mechanism of stimulated emission can take place and the medium can act as a laser or an optical amplifier. The pump power must be higher than the lasing threshold of the laser.

Ruby laser Solid-state laser with ruby as gain medium

A ruby laser is a solid-state laser that uses a synthetic ruby crystal as its gain medium. The first working laser was a ruby laser made by Theodore H. "Ted" Maiman at Hughes Research Laboratories on May 16, 1960.

Deuterium arc lamp

A deuterium arc lamp is a low-pressure gas-discharge light source often used in spectroscopy when a continuous spectrum in the ultraviolet region is needed.

Aircraft warning lights

Aircraft warning lights are high-intensity lighting devices that are attached to tall structures and are used as collision avoidance measures. Such devices make structures more visible to passing aircraft and are usually used at night, although they may be used during the day as well. These lights need to be of sufficient brightness in order to be visible for miles around the structure.

Super Trouper is the registered trademark of a series of follow spotlights used in stadium, concert, and special-event lighting. The lights are manufactured by Strong Lighting of Omaha, NE which acquired the Super Trouper and its larger cousin, the Gladiator, from its former manufacturer Syncrolite who had acquired them from Ballantyne Strong of Omaha, Nebraska in November 2016.

Brian E. Dalrymple is an Ontarian fingerprint scientist known for introducing for the first time the use of lasers as a forensic light sources for fingerprints and other evidence detection, using the Argon Ion Lasers to detect the inherent fluorescence of the latent fingerprints and finding fluorescing evidence. That was the beginning of a real revolution in the forensic identification field. Brian Dalrymple also become the first to use this forensic technique on a real case.

References

  1. Stoilovic, M., ‘Detection of Semen and blood stains using the Polilight as a light source’, Forensic Sci Int, 51; 1991; p.289-96.
  2. Warrener,R.N., Kobus,H.J., M.Stoilovic. ‘An Evaluation of the Reagent NBD Chloride for the Production of Luminescent Fingerprints on Paper:I. Support for a Xenon Arc Lamp being a Cheaper and Valuable Alternative to Argon Ion Laser as an Excitation Source’. Forensic Science International, 23, 1983, pp 179188.
  3. 1 2 Polilight forensic lamp, Powerhouse Museum.
  4. 2005 Australian Export Awards, DSB December 2005.