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1. WO1997028429 - METHOD AND SYSTEM FOR SUPPRESSING UNWANTED REFLECTIONS IN AN OPTICAL SYSTEM

Publication Number WO/1997/028429
Publication Date 07.08.1997
International Application No. PCT/US1997/000994
International Filing Date 22.01.1997
Chapter 2 Demand Filed 25.07.1997
IPC
G01N 21/21 2006.01
GPHYSICS
01MEASURING; TESTING
NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
21Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
17Systems in which incident light is modified in accordance with the properties of the material investigated
21Polarisation-affecting properties
G01N 21/956 2006.01
GPHYSICS
01MEASURING; TESTING
NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
21Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
84Systems specially adapted for particular applications
88Investigating the presence of flaws, defects or contamination
95characterised by the material or shape of the object to be examined
956Inspecting patterns on the surface of objects
CPC
G01N 21/21
GPHYSICS
01MEASURING; TESTING
NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
21Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
17Systems in which incident light is modified in accordance with the properties of the material investigated
21Polarisation-affecting properties
G01N 21/95623
GPHYSICS
01MEASURING; TESTING
NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
21Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
84Systems specially adapted for particular applications
88Investigating the presence of flaws or contamination
95characterised by the material or shape of the object to be examined
956Inspecting patterns on the surface of objects
95623using a spatial filtering method
G01N 21/95684
GPHYSICS
01MEASURING; TESTING
NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
21Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
84Systems specially adapted for particular applications
88Investigating the presence of flaws or contamination
95characterised by the material or shape of the object to be examined
956Inspecting patterns on the surface of objects
95684Patterns showing highly reflecting parts, e.g. metallic elements
Applicants
  • GENERAL SCANNING INC. [US]/[US]
Inventors
  • SVETKOFF, Donald, J.
  • KILGUS, Donald, B., T.
Agents
  • SYROWIK, David, R.
Priority Data
594,69631.01.1996US
Publication Language English (EN)
Filing Language English (EN)
Designated States
Title
(EN) METHOD AND SYSTEM FOR SUPPRESSING UNWANTED REFLECTIONS IN AN OPTICAL SYSTEM
(FR) PROCEDE ET SYSTEME D'ELIMINATION DES REFLEXIONS INDESIRABLES DANS DES SYSTEMES OPTIQUES
Abstract
(EN)
A method and system are provided for suppressing or filtering multiple reflections which corrupt photometric or height measurements within optical systems such as imaging systems. The reflections may originate within the instrument (i.e., back reflections) or may be inter-reflections between one or more surfaces in a scene. In one embodiment, a beam of electromagnetic energy generated by a source is polarized in a first rotational sense, is transmitted to a point of interest (i.e., scene) of an object, is reflected and received by a receiver having a polarizer which passes reflected electromagnetic energy having a second rotational sense opposite the first rotational sense. In this way, unwanted reflections from the point of interest having the first rotational sense are suppressed and back-reflections to the source of electromagnetic energy are substantially eliminated. In another embodiment, a detector which normally back-reflects a portion of electromagnetic energy it receives along a first axis, has a surface normal which is maintained in a fixed, non-colinear relation to the first axis and back-reflected electromagnetic energy is prevented from reaching the scene and is not received by any other detector of the imaging system.
(FR)
L'invention porte sur un procédé et un système d'élimination ou de filtrage des réflexions multiples indésirables qui perturbent les mesures photométriques ou de hauteur dans des systèmes optiques notamment de réalisation d'images. Les réflexions peuvent provenir de l'appareil (par exemple rétroréflexions) ou résulter d'interactions avec une ou plusieurs des surfaces d'une scène. Dans une première variante, le faisceau d'énergie électromagnétique provenant d'une source est polarisé dans un premier sens rotationnel, puis transmis sur un point d'intérêt d'un objet (par exemple une scène), puis réfléchi et reçu par un récepteur muni d'un polariseur qui laisse passer l'énergie électromagnétique polarisée dans un second sens opposé au premier. De cette manière les réflexions indésirables polarisées dans le premier sens provenant du point d'intérêt sont supprimée et les rétroréflexions vers la source pratiquement éliminées. Dans une deuxième variante, un détecteur qui renvoie normalement une partie de l'énergie électromagnétique qa'il reçoit dans une première direction voit la normale à sa surface maintenue dans une relation fixe et non coaxiale avec le premier axe, ce qui empêche l'énergie électromagnétique rétroréfléchie d'atteindre la scène et d'être reçue par aucun des autres détecteurs du système de formation d'images.
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