An alternative illumination source to ambient lighting; used in forensics to enhance visualization for observation and photography of questioned documents, latent prints, biological fluid, trace materials, residues, and imprints. Certain wavelengths of alternate light sources (ALS) are used to enhance visualization of injury, injury patterns, or other tissue defects (e.g., visualizing antemortem tattoos during postmortem examinations).
Synonyms: ALS, alternative light source, forensic light source
Variations: UV light, IR light, blue light, green light
