Patent ID: 7635830
Filing Date: 2009-12-22
Classification: G01N

Abstract:
1. An optical system adapted to generate an illuminated pattern on a surface of a material comprising: a material support unable support said material for movement of said material relative to said illuminated pattern at a variable transport speed in a transport direction; an illumination arrangement including a plurality of light sources, said illumination arrangement being usable to generate said illuminated pattern on said surface of said material moving at said variable transport speed as an illuminated strip having a strip width in said transport direction; a detection device usable to detect light emitted by said light sources; a control device usable to selectively operate one, and a group of said plurality of light sources, in a pulsed manner; a light source chronological behavior of at least one light source of said plurality of light sources, said light source chronological behavior including a light source switched-on time length, a light source switching-on delay time length immediately preceding said light source switched-on time, and a light source switched-off time length subsequent to said light source switched-on time, said light source switched-on time length being a function of said variable transport speed and of optical properties of said material; a detection device chronological behavior of said detection device, said detection device chronological behavior including a detection device exposure time length and a detection device off time length, said detection device off time length immediately following said detection device exposure time, said detection device off time length being set as a function of said variable transport speed of said material, said light source switched-on time length and said immediately preceding light source switching-on delay time length being synchronized with, and being less than said detection device exposure time length; a first time sum set by said control device and including said light source switching-on delay time length and said light source switched-on time length; and a second time set by said control device and including said detection device exposure time length, said second time being greater than said first time sum, said light source switched-on time length and said light source switching-on delay time length being completely within said detection device exposure time length which is greater than said light source switching-on delay time length and said light source switched-on time length, said surface of said material being illuminated with a constant amount of light independently of said variable transport speed of said material.