Alternate Light Sources (ALS) are tools that can permit investigators to locate, process, and photograph otherwise invisible evidence. Understanding how these devices work is helpful in applying them correctly at the crime scene or in the laboratory. This course begins with a discussion of the properties of light and luminescence and culminates in the use of the ALS to visualize and photograph items of evidence. A review of basic photography and the use more advanced photographic techniques to optimize image quality will be included.
A variety of different types of Alternate Light Sources will be on-hand for use by the students. The ability to use different types of units will permit students to judge which type of light source best suits their needs and will assist lead-workers in establishing their agency’s protocols, procedures, and workflow.
The types of evidence on which ALS units are commonly utilized include fingerprint evidence, trace evidence (like hairs and fibers, narcotics, gunshot residue, and body fluids), and bodily injuries. In-class hands-on exercises will include all of these types of evidence.
Basic Photography Review
Mechanics of Luminescence
Selection of Appropriate Light Sources including Cost Factors
How to Obtain the Best Possible Photographic Results
Photography of Biological Fluids and Other Biological Materials using Luminescence
Identifying False Positive Reactions
Photography of Latent Fingerprints and Trace Evidence using Luminescence
Selection of Cameras, Lenses, and Accessories
This course will heavily emphasize instruction using hands-on techniques. The students will photograph realistic evidence to observe the photographic results of the techniques learned and used in class.
Due to the amount of hands-on training in this course, enrollment is limited to 20 students. Students are encouraged to bring the digital camera used in their work.
This is an advanced course; students are expected to have an understanding of basic photography and camera operation prior to attendance.
Basic Photography Review Lecture (2 Hours)
Mechanics of Exposure
Image Quality and Size
Properties of Light and Luminescence Lecture (1 Hour)
Introduction to Alternate Light Sources (1 Hour)
Lunch (1 Hour)
Understanding Color and Contrast Lecture (1/2 Hour)
Using Colored Filters to Increase Contrast Practical Exercise and Review (2 Hours)