What is the primary use of an alternative light source (ALS) in a forensic context?

The primary use of an alternative light source (ALS) in a forensic context is to detect bodily fluids such as semen. The unique properties of semen allow it to fluoresce under specific wavelengths of light emitted by an ALS, making it easier to identify and document at a crime scene, particularly in sexual assault investigations. This capability is crucial for forensic nurses and other professionals involved in the collection of evidence, as the presence of semen can help to corroborate a victim's account and provide physical evidence in legal cases.

Alternate options such as detecting gonorrhea or identifying human papilloma virus pertain more to medical diagnostics rather than forensic applications. Similarly, pelvic inflammatory disease is a clinical diagnosis that does not utilize the techniques involved with an ALS. Therefore, the use of an alternative light source is particularly focused on identifying bodily fluids, like semen, which is vital for forensic evidence collection and analysis.