The new VISAS fingerprint powder is a powder that is used to develop fingerprints by means of a fingerprint brush. The natural colour of the powder is white.
The powder has a special property though, when excited with high intensity IR light of 980 nm it emits light in the visible part of the spectrum at a shorter wave length, around 550 nm (figure 1). This is called an anti-Stokes reaction.
Anti-Stokes is the reverse of what happens with regular fluorescent fingerprint powders, these powders are excited with a bandwidth of light and then show fluorescence at a longer wave length. This is called a Stokes reaction.
Since a lot of materials like coloured plastics, printing ink and so on fluoresce in the same region as regular fluorescent fingerprint powders, very poor contrast is obtained between the powdered fingerprint and the background.
No known natural substances show the same anti-Stokes properties as the VISAS powder and since the excitation light (infra-red, 980 nm) is not visible to the naked eye or camera, this almost completely eliminates the background. In a darkened room you will only see or image the developed fingerprint.
The powder can be used to develop latent fingerprints. It can also be used as an alternative to staining solutions for cyanoacrylate like Basic Yellow 40, Ardrox and so on.