VUV Illumination for Latent Fingerprint Detection
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Solution Overview
Problem
Current fingerprint detection technologies rely on trial-and-error methods and require chemical processing, which can damage surfaces and destroy DNA evidence, and are limited by low contrast visibility of latent fingerprints.
Innovation Solution
A device using a broad-spectrum illumination source with a waveband filtering system that emits specific wavelengths, such as VUV or infrared, to illuminate latent fingerprints, causing the substrate to fluoresce while the fingerprint absorbs the light, allowing for visible-spectrum imaging without chemical treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If chemical processing techniques (e.g., ninhydrin) are used to lift latent fingerprints, then fingerprint visibility is improved, but the surface may be damaged and underlying DNA or material evidence may be destroyed
Solution Approach 1:
The patent replaces chemical processing methods with optical detection methods. Specifically, it uses vacuum ultraviolet (VUV) illumination at wavelengths around 160-200 nm to illuminate latent fingerprints, causing the substrate to fluoresce while the fingerprint absorbs the light, creating visible contrast without any chemical treatment. This substitution eliminates the harmful effects of chemicals on the surface and underlying evidence while maintaining fingerprint detection capability
Solution Approach 2:
The patent changes the illumination wavelength parameter to achieve fingerprint detection. By using VUV light at specific wavelengths (160-200 nm) that are absorbed by fingerprint residues while causing fluorescence in the substrate, the method creates sufficient contrast for detection without chemical processing. This parameter change enables non-destructive detection while preserving the integrity of the surface and any underlying evidence
2Device complexity
If traditional optical detection methods are used for latent fingerprints, then the detection process is simple, but the low contrast makes fingerprints difficult to resolve and collect
Solution Approach 1:
The patent changes the illumination wavelength parameter from visible light to vacuum ultraviolet (VUV) range (160-200 nm). This parameter change exploits the differential absorption and fluorescence properties of fingerprint residues versus the substrate at these wavelengths, creating high contrast images that are easily resolvable while maintaining relative detection simplicity
3Adaptability or versatility
If trial-and-error techniques are used to locate and visualize fingerprints, then the detection method is flexible, but significant time is required to bring the fingerprint into relief
Solution Approach 1:
The patent replaces trial-and-error localization techniques with direct VUV illumination that causes the substrate to fluoresce while fingerprint areas absorb the light. This substitution allows for immediate visualization of fingerprints upon illumination without requiring multiple attempts or time-consuming processing steps, significantly reducing detection time while maintaining flexibility in application
Solution Approach 2:
The patent applies VUV illumination directly to the substrate without requiring preliminary chemical treatment or surface preparation. The fluorescence effect occurs immediately upon illumination, bringing the fingerprint into relief instantly and eliminating the time-consuming trial-and-error process traditionally required to locate and visualize latent prints
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables effective detection of latent fingerprints without damaging the surface or destroying evidence, improving contrast and visibility for imaging, and reducing the need for chemical processing.
Implementation Method 1
causing the substrate to fluoresce while the fingerprint absorbs the light
Implementation Method 2
the desired wavelength range is one that is absorbed by the contaminant while causing the substrate to fluoresce
Data Source
AI summary
Systems, devices, and methods for detecting a contaminant on a substrate are discussed herein. Variations of such systems, devices, and methods may include one or more illumination sources that emit illumination at one or more desired wavelength ranges to illuminate one or more areas on the substrate; where the desired wavelength range is one that is absorbed by the contaminant while causing the substrate to fluoresce. Such fluorescence may be detected with a visible-spectrum detector, which will also detect the contaminant as a darker contrast area against the fluorescence. In some variations, an illumination source includes a broad-spectrum light source and a waveband filtering device that filters all but the desired illumination waveband out of the broad-spectrum light generated by the broad-spectrum light source.