ALS
Definition
Illumination used to search for or document optical responses under selected conditions. Excitation conditions, viewing filters and background affect what is visible. A fluorescent or absorbing area is a screening observation.
- Context
- Evidence searching
For example, a bright area on clothing can guide sampling while remaining compatible with more than one material or background source.
It does not identify blood, semen or another material without suitable further examination.
Related terms
- Barrier Filter
- An optical long-pass filter placed over the camera lens and worn as goggles by the examiner during ALS examination; blocks the excitation...
- Irradiance
- Radiant power incident per unit area; distinct from electrical lamp power. Unwanted wavelengths can pass through a measurement path and add signal...
- Screening Observation
- A finding used to guide further examination without claiming specific material identification. Screening can guide further examination while allowing alternative causes. An...