How is alternative light source used in forensic science?

UV alternate light sources can reveal the following: seminal fluid, saliva and urine stains. Also, certain narcotics will fluoresce as will bone and teeth fragments. Other uses of alternate light sources Indeed, many forms of physical evidence will fluoresce.

How is alternative light photography used in forensic science?

Alternative light sources are typically used in crime scene investigation and post mortem examinations to identify many forms of evidence. Utilizing ultraviolet light, investigators can identify physiological fluids like semen, urine, and saliva through the fluids’ natural fluorescent properties.

How is alternative light source used?

Abstract. Alternative light sources (ALSs) are commonly used at crime scenes and in forensic laboratories to collect evidence such as latent fingerprints, body fluids, hair, and fibers. … Ninety-three percent of the patients had no visible evidence of external injuries on physical examination.

What is an alternate light source forensics?

A forensic examination that is conducted only using the visible light wavelengths that are emitted from conventional bulbs may not reveal all the evidence present. The use of what has been termed alternate light sources can reveal otherwise hidden evidence. …

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How is light used in forensic science?

Ultraviolet (UV) light technologies are used for multiple purposes in forensic investigations, including authenticating paintings and other fine art, authenticating signatures, analyzing questioned documents , illuminating latent fingerprints at crime scenes and trace evidence on clothing, analyzing ink stains, and …

What is alternative light?

Examination of crime scenes using monochromatic light sources (light of one specific wavelength) can assist in locating and identifying potential evidence. … Devices providing monochromatic light at specific wavelengths are referred to as Alternate Light Source (ALS).

Why does blood glow under UV light?

A bloodstain exposed to UV light absorbs all light of that bandwidth and does not reflect back – that is to say, it does not fluoresce in any way. Thus the stain will appear black under UV.

Does female discharge glow under black light?

The answer is yes, and no. Female discharge is not as bright under a blacklight as come. Because of the particular chemical composition male bodily sexual fluid is the brightest. As for female fluids, unfortunately, we can only say that it’s not going to glow as bright.

How sensitive is alternative light source?

Sensitivity of ALS on days 1, 7, and 14 was 76.8%, 69.6%, and 60.7%, respectively, compared to 69.6%, 60.0%, and 32.1% for white light. The specificity of ALS on days 1, 7, and 14 was 51.6%, 59.7%, and 53.2%, respectively, compared to 71.0%, 81.4%, and 86.9% for white light.

What does blood look like under a UV light?

Blue-white stains appear all over the floors, walls and objects sitting around the crime scene! … You see, blood does not fluoresce by applying UV or visible blue light.

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What are the forensic light sources?


  • Forensic Light Sources.
  • Reflective Ultra-Violet Imaging System [RUVIS]
  • Fingerprint imaging systems and software.
  • Automated Fingerprint / Palmprint Identification Systems [AFIS/APIS]
  • Raman microscopes.
  • X-Ray Fluorescence.

Does Luminol destroy DNA?

Luminol has been widely used in the field of crime scene investigations to detect latent blood; however, luminol has the tendency to destroy DNA evidence. … DNA was extracted from blood-containing denim substrates after fluorescein was applied to the substrates.

Can black light detect blood?

Beneath a black light, blood turns black, unless sprayed with luminol which gives it a blue-glow. Saliva, semen and urine also glow when hit with a black light. Most biological fluids contain fluorescent molecules to help them glow.

What color is urine under black light?

Urine fluoresces as a pale yellow color. The best way to see urine under a blacklight is to wait until evening when it is dark.

How important is light in forensic photography?

It is most important for forensic photographers to understand the physiological changes that take place during a skin injury. These changes from a normal state to an injured state to a healing state permit us to differentiate among the contusions illuminated by light sources of various wavelengths.

How much UV light is in sunlight?

Most of the natural UV light people encounter comes from the sun. However, only about 10 percent of sunlight is UV, and only about one-third of this penetrates the atmosphere to reach the ground, according to the National Toxicology Program (NTP).