Patent ID: 9104900
Filing Date: 2015-08-11
Classification: A61B,G06K

Abstract:
1. A system for recording ridge patterns, the system comprising: a light source configured to emit light; an element having a scanning surface configured to reflect light based on positions of the ridge patterns on the scanning surface; an optical system configured to form at least one image of the scanning surface based on the reflected light; an image sensor with a plurality of light-sensitive elements, the image sensor configured to generate a plurality of intermediate images based on the at least one image formed by the optical system; an electronic memory configured to store the plurality of intermediate images; and a processing unit configured to generate an output image by averaging intensity values of respective elements of the plurality of intermediate images corresponding to a same region of the scanning surface and assign the average intensity value to a corresponding element of the output image, wherein each of the plurality of intermediate images is linked electrically with the plurality of light-sensitive elements of the image sensor, and the plurality of light-sensitive elements are linked optically with the light source and the scanning surface, wherein, in a spectral range of sensitivity of the image sensor, a total flux of useful light with wavelengths less than a boundary wavelength L is at least five times greater than a total flux of stray light with wavelengths greater than the boundary wavelength L, and L satisfies the condition: wherein L is the boundary wavelength of the light emitted from the light source, expressed in micrometers, T is an interval between centres of the plurality of light sensitive elements of the image sensor, expressed in micrometers, A is a numerical aperture of the optical system configured to form the at least one image of the scanning surface on the image sensor, and N is a number of light-sensitive elements in the image sensor per one element of the output image.