Latent fingerprint displaying method

A technology of latent fingerprints and fingerprints, which is applied in the direction of human identification, etc., and can solve the problems of reduced sensitivity, poor display of fingerprints on the surface of wet objects, and background interference of fingerprints, etc.

Inactive Publication Date: 2014-07-09
CHINA CRIMINAL POLICE UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the powder display method has high requirements on the powder process, which is easy to leave false features, and the display effect of the fingerprint on the surface of the wet object is not good.
In addition, there are many kinds of objects left in the handprints at the scene, and their physical and chemical proper

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0065] Dip a small amount of β-NaYF with a fingerprint brush 4 : Yb, Er up-converting luminescent nanoparticles gently brush on the fingerprint to be detected on the surface of the sticky note, after finding the fingerprint line, use a clean fingerprint brush to remove the excess β-NaYF 4 :Yb, Er up-conversion luminescent nanoparticles are brushed off until fingerprints with clear lines appear, and then the 980 nm infrared excitation light source is used to expand the beam through the beam expander, and the beam expansion size is adjusted according to the size of the fingerprint. The light is irradiated on the displayed fingerprint, and after the infrared light is filtered out by the filter, the camera is used for imaging. figure 1 shown.

Embodiment 2

[0067] β-NaYF with a fingerprint brush 4 : Yb, Tm up-conversion luminescent nanoparticles gently brush on the fingerprint to be detected on the glass surface, after finding the fingerprint line, use a clean fingerprint brush to remove the excess β-NaYF along the fingerprint pattern 4 : Yb, Tm up-conversion luminescent nanoparticles are brushed off until fingerprints with clear lines appear, and then the 980 nm infrared excitation light source is used to expand the beam through the beam expander, and the beam expansion size is adjusted according to the size of the fingerprint. The light is irradiated on the displayed fingerprint, and after the infrared light is filtered out by the filter, the camera is used for imaging. figure 2 shown.

Embodiment 3

[0069] β-NaYF with a fingerprint brush 4 : Yb, Ho up-conversion luminescent nanoparticles are gently brushed on the fingerprint to be detected on the surface of the stainless steel sheet. After the fingerprint line is found, use a clean fingerprint brush to remove the excess β-NaYF 4 :Yb, Ho up-conversion luminescent nanoparticles are brushed off until fingerprints with clear lines appear, and then a 980 nm infrared excitation light source is used to expand the beam through a beam expander. The size of the expanded beam is based on the size of the fingerprint After adjustment, the expanded infrared light is irradiated on the displayed fingerprint. After the infrared light is filtered out by the filter, the camera is used for imaging. After imaging, as attached image 3 shown.

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Abstract

The invention discloses a latent fingerprint displaying method, and belongs to the technical field of fingerprint identification. The invention provides the latent fingerprint displaying method which is high in detection sensitivity, less in damage to the fingerprint and simple to operate. The latent fingerprint displaying method comprises the following steps of dipping a fingerprint hair brush into an up-conversion luminescence nano-particle powder, covering the fingerprint with the powder, after finding a fingerprint streakline, removing the powder on the hairbrush, and brushing along the orientation of the streakline until the streakline is clear. Infrared light directly radiates the area where the fingerprint is displayed, the surface of the fingerprint generates bright visible light, and then a fingerprint image can be shot by a digital camera. The other latent fingerprint displaying method comprises the following steps of sequentially adding absolute ethyl alcohol and water into the up-conversion luminescence nano-particle powder, stirring well, and ultrasonically dispersing to obtain a mixture; mixing the mixture with a surfactant aqueous solution and stirring well, thus obtaining the small-particle suspension liquid of the up-conversion luminescence nano-particles.

Description

Technical field [0001] The present invention is a fingerprint identification technology field, and it involves a method of showing a sub -print show. Background technique [0002] Perform personal identification of criminals through handprint inspection, which has become a favorable means to crack down on crimes, and handprints are therefore known as "the first of evidence."The handprint inspection is a process of investigating, manifested, analyzed, extracted, and sample handprints on the on -site handprints, and the on -site fingerprints are the same as the sample handprint.The appearance and extraction of on -site handprints are the core and foundation of the entire handprint inspection process.According to the different principles of the manifestation, the fingerprints can be roughly divided into two categories: physical explanation and chemical expression.Among them, physical expression includes powder expression, fumigation dyeing, and optical expression, etc.; Chemical exp...

Claims

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Application Information

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IPC IPC(8): A61B5/117
Inventor 王猛史力民张晓梅张彦春刘代富张洪国李明陈立宏伊魁宇
Owner CHINA CRIMINAL POLICE UNIV
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