Specular Reflection Latent Fingerprint Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for extracting latent fingerprints are time-consuming, inconsistent, and require trial-and-error, as they often involve adding chemicals or powders that can disturb surface chemicals, and are limited to detecting fingerprints of a specific size and type.
Innovation Solution
A non-contact automatic optical fingerprint system utilizing a critically aligned optical sensor that captures specular reflections, with the light source and camera settings configured to reject diffuse reflections, allowing for the detection of fingerprints by processing glare, which conventional systems typically reject.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods use chemicals or powders to extract fingerprints, then fingerprint detection is achieved, but the surface chemicals are disturbed and the process becomes time-consuming and inconsistent
Solution Approach 1:
The patent replaces chemical and mechanical fingerprint extraction methods with an optical detection system. The system uses a light source and camera to capture specular reflections from the fingerprint ridges, eliminating the need for chemicals or powders entirely. This substitution enables non-contact, automatic detection that is both faster and more consistent than conventional methods.
Solution Approach 2:
The patent introduces specular reflection as an intermediary mechanism to detect fingerprints. By capturing the glare reflected from fingerprint ridges at a specific angle, the system creates an optical signature of the fingerprint pattern without physically contacting or chemically treating the surface,从而实现 rapid and reliable detection.
2Measurement precision
If conventional optical systems reject specular reflection (glare), then diffuse reflection images are obtained, but fingerprint features visible in glare cannot be seen
Solution Approach 1:
The patent converts the harmful specular reflection (glare) into a beneficial signal for fingerprint detection. Instead of rejecting glare as conventional systems do, the patent positions the camera to capture specular reflections from fingerprint ridges. The glare becomes the primary carrier of fingerprint information, revealing features that are invisible in diffuse reflection images.
Solution Approach 2:
The patent inverts the conventional optical approach by accepting and utilizing specular reflection instead of rejecting it. While traditional systems filter out glare to obtain diffuse reflection images, this patent positions the detection system to capture glare at a specific angle, thereby inverting the standard optical methodology to achieve superior fingerprint detection.
3Area of stationary object
If a single light source and diffuse reflectance are used, then the system is simple, but it is limited to fingerprinting small areas only
Solution Approach 1:
The patent extends the detection area by introducing angular dimension to the optical system. By positioning the camera at a specific angle relative to the light source (critical alignment), the system captures specular reflections across a larger surface area. This angular configuration allows the detection of entire fingers or multiple fingers simultaneously, rather than being limited to small localized areas.
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
This approach enables efficient and consistent detection of latent fingerprints by discriminating against diffuse reflections, allowing for high-resolution imaging of fingerprints without disturbing the surface chemicals, and can detect fingerprints on larger areas by using a camera with a field of view that covers the entire sample surface.
Implementation Method 1
a critically aligned optical sensor comprising a light source positioned relative to a camera to utilize specular reflection from an irradiated sample surface
Data Source
AI summary
This document relates to systems and method for latent fingerprint detection using specular reflection (glare). An exemplary system may include a light source alignment portion configured to align a light source at an illumination angle relative to a sample surface such that the light source illuminates a sample surface so that the surface produces specular reflection. The system may also include a specular reflection discriminator that directs the produced specular reflection to an optical detector aligned relative to said sample surface at an alignment angle that is substantially equal to an angle of reflection of the produced specular reflection. Preferably, the directed specular reflection does not saturate the optical detector; and the optical detector captures the specular reflection from the sample surface and generates image data using essentially only the specular reflection.