The task of examining a crime scene for traces of biological fluids without compromising evidence or causing physical disturbance may appear daunting. However, detectives worldwide accomplish this feat on a daily basis, successfully solving crimes and gathering crucial evidence. How is this achieved? The answer lies in utilizing specialized forensic glasses and illuminating the area with meticulously-filtered light, allowing investigators to observe the results firsthand.
HOW FORENSIC GLASSES WORK
The identification of biological evidence, including blood, semen, saliva, and urine, holds significant importance in crime scene investigations. Employing forensic light sources provides a simple, presumptive, and non-destructive method for detecting various types of biological evidence. This is possible due to the natural characteristics of such substances, including light absorption or fluorescence effects.
So, how does this system function? The explanation lies in a few fundamental scientific principles. Certain fluids exhibit visible reflections when exposed to X-rays or ultraviolet (UV) light. This visibility stems from the fact that different substances react and become observable at distinct wavelengths. While these substances may be invisible to the naked eye under ordinary lighting conditions, they become prominently visible when a UV lamp is directed towards them, provided the observer possesses the appropriate color filter capable of interpreting the necessary wavelength. This is where forensic glasses play a crucial role.
Forensic glasses effectively filter out light from all wavelengths except the specific one selected, thereby revealing the desired substance that the investigator seeks. Once the evidence is identified, it can be documented through photography using a camera equipped with a lens of the same color as the forensic glasses that initially detected the substance. Additionally, samples can be collected for further analysis.
LENS FILTERS IN FORENSIC GLASSES
Typically, three different filter colors, namely red, orange, and yellow, are utilized in this process, with each designed to unveil a distinct wavelength. The properties associated with each filter color, measured in nanometers (nm), are outlined as follows: red lenses reveal a wavelength of 583 nm, orange lenses reveal a wavelength of 549 nm, and yellow lenses reveal a wavelength of 480 nm.
Given their significance in crime scene investigations, forensic glasses have emerged as a highly valuable tool for detectives and investigators. They prove essential for examining crime scenes and analyzing evidence collected from such scenes. Just like regular eyewear, forensic glasses come in a range of frame formats to cater to individual preferences and specific requirements of each crime scene. Phillips Safety offers four distinct styles of forensic glasses for each lens filter, including options with a wrap-around design and models that can be worn over prescription eyewear.
The different styles of forensic glasses offer a range of features, such as side protection, adjustable temple bars, lightweight nylon frames resistant to chemicals, rubberized nose pads, and rubberized temple bars. All styles have been safety rated to meet ANSI Z87 standards and are available with any of the aforementioned three lens colors. If you are seeking forensic glasses, make sure to check Phillips Safety’s forensic glasses collection.