Multi-band light source has been widely used in many developed areas because of its wide application range and good application effect. However, as multi-band light source is a relatively high-tech product, there is no manufacturer and model of theoretical research and application in China in the past few years. When people buy multi-band light source, they do not understand the detailed objectives of measuring the function of multi-band light source, and they only look at a brief description and a few experiments in the use of time, in the palm of exploration. Some units also imagine the use of multi-band light source too well. Some units only use multi-band light source as a general light source after purchasing multi-band light source.

First step: white light search. After entering the scene, the first search should be carried out by using the white light output of the multi-band light source for the first time. This is the same as the previous method when we use the strong lamp for site investigation. The main purpose is to check whether there are dust footprints, dust fingerprints and various trace evidence.

The second step: blue and green search. Then shade the scene as far as possible, if allowed, can be re-searched at night, the use of multi-band light source blue, green light, with orange filters for the second scene survey (also can use 450 nm band / yellow filter), can make a lot of suspicious substances such as body fluid, fiber, paint fragments and shooting residue. Things give out inherent fluorescence. If there is a body, the use of blue and green light in the body and clothing on the examination of semen spots, saliva, hair, fiber, scars or bite marks.

The third step: change the output wavelength to find. Change the output wavelengths and replace the filter, and look for many times to see if there are any new discoveries.

The fourth step: Flash processing. When fingerprints are flashed, the materials that can be taken back to the laboratory for processing should be brought back to the laboratory as soon as possible. If it is inconvenient, fingerprints can be flashed on the spot by fluorescent powder or other treatment methods. The application of multi-band light source in field exploration undoubtedly provides convenience for observing and taking photos of trace evidence directly on the spot, and then greatly improves the rate of discovery and utilization of trace evidence on the spot.

Nowadays, few light sources are welcomed by more public security departments, and multi-band light sources have gradually become indispensable for criminal investigation.