Deflectometry Measurement System
AssigneeLambda-X
InventorsPhilippe Antoine, Didier Beghuin, Luc Joannes
Life of this patent
Estimating the term…
Abstract
A system for measuring (200) a sample (2) by deflectometry comprising: a source (10) for generating a light beam in a source plane (105); an illumination module (19) for forming an illumination beam (9) comprising: a first converging optical element (18); a first selection optical element (16) with a first aperture (160); reflective matrix optical modulation means (30) to form a pattern (7), said first aperture (160) being configured to control the angles of said illumination beam (9) on said reflective matrix optical modulation means (30); a Schlieren lens (20) for obtaining an angle-intensity encoding of said pattern (7) on the sample (2); imaging (40) and detecting means (50) for detecting an image of said sample (2).
Claims32
A system for measuring (200) a sample (2) by deflectometry comprising:
- a source (10) for generating a light beam in a source plane (105);
- an illumination module (19) comprising:
- a first converging optical element (18);
- a first selection optical element (16) having a first aperture (160), said first selection optical element (16) being positioned between said source plane (105) and said first converging optical element (18);
- said illumination module (19) being configured to generate an illumination beam (9) from said light beam of said source (10);
- matrix optical modulation means (30) in reflection, for forming a pattern (7) from said illumination beam (9);
- said first aperture (160) being configured to control angles of incidence of said illumination beam (9) on said matrix optical modulation means (30) in reflection;
- a Schlieren lens (20);
- said measuring system (200) being configured such that said pattern (7) is adapted to illuminate said Schlieren lens (20) so as to obtain an angle-intensity encoding of said pattern (7) into an inspection light beam (99);
- imaging means (40) for forming an image of said sample (2) after interaction of said inspection light beam (99) with said sample (2), said Schlieren lens (20) being positioned between said matrix optical modulation means (30) and said imaging means (40) along an optical path of a light beam generated by said source (10) when the latter is activated;
- matrix detection means (50) for detecting said image of said sample (2) formed by said imaging means (40).
The measuring system (200) according to the preceding claim characterized in that said matrix optical modulation means (30) are positioned in a modulation plane (195) optically conjugate to said source plane (105), said illumination beam (9) being spatially limited at the level of said matrix optical modulation means (30) in reflection by at least one of the following means:
- a second selection optical element (12) having a second aperture (120), positioned in said source plane (105);
- a third selection optical element (36) having a third aperture (360), positioned in said modulation plane (195);
- a source (10) comprising a spatially limited light source (15), preferably said light source (15) being a light emitting diode matrix.
The measuring system (200) according to any one of the preceding claims characterized in that said first selection optical element (16) is positioned in an object focal plane (185) of said first converging optical element (18).
The measuring system (200) according to any of the preceding claims characterized in that it further comprises:
- a third selection optical element (36) having a third aperture (360), said third selection optical element (36) being positioned at the level of said matrix optical modulation means (30).
The measuring system (200) according to any of the preceding claims characterized in that:
- said illumination module (19) is an illumination module 4F comprising:
- a second converging optical element (14) positioned between said source (10) and said first selection optical element (16), and configured such that:
- its object focal plane coincides with said source plane (105);
- its image focal plane coincides with said object focal plane (185) of said first converging optical element (18) positioned between said first (18) and second (14) converging optical elements,
- said image plane of the illumination module (19) coincides with the image focal plane of the first converging optical element (18).
The measuring system (200) according to any one of the preceding claims characterized in that said matrix optical modulation means (30) are matrix phase modulation means (30).
The measuring system (200) according to the preceding claim characterized in that the matrix phase modulation means (30) comprise a liquid crystal on silicon matrix.
The measuring system (200) according to any of the preceding claims characterized in that it further comprises:
- beam splitting means (60) configured so as to obtain from said illumination beam (9) resulting from said illumination module (19):
- a first light beam (91) deflected by said beam splitter (60) along a first optical path (61) directed towards said matrix optical modulation means (30);
- a second light beam (92) transmitted by said beam splitter (60) along a second optical path (62) resulting from a reflection of said first light beam deflected (91) by said matrix optical modulation means (30).
The measuring system (200) according to the preceding claim characterized in that said first (61) and second (62) optical paths are parallel.
The measuring system (200) according to the preceding claim characterized in that said first (61) and second (62) optical paths are perpendicular.
The measuring system (200) according to the preceding claim characterized in that said illumination beam (9) resulting from said illumination module (19) is directed along an optical axis A, said polarizing beam splitter (60) is configured such that the optical axis A is perpendicular to said second optical path (62).
The measuring system (200) according to any one of the preceding claims characterized in that said source (10) comprises a light source (15) and a second selection means (12) having a second aperture (120) for spatially limiting a light beam resulting from said light source (15).
The measuring system (200) according to the preceding claim characterized in that said second selection means (12) is positioned in said source plane (105).
The measuring system (200) according to any of the preceding claims characterized in that said source (10) comprises a spatially limited light source (15), preferably said light source is a LED matrix.
The measuring system (200) according to any one of the preceding claims characterized in that said first aperture (16) has a first aperture surface area (160) of less than 50 mm2, preferably less than 25 mm2 and even more preferably less than 10 mm2.
The measuring system (200) according to any one of the preceding claims characterized in that said first aperture (160) is centered on said optical axis A.
The measuring system (200) according to the preceding claim characterized in that the non-planar mirror is concave.
The measuring system (200) according to any one of the preceding claims characterized in that said Schlieren lens (20) is positioned between said projection device (100) and said imaging means (40).
The measuring system (200) according to any one of the preceding claims characterized in that said Schlieren lens (20) is positioned in an optical path between said matrix phase modulation means (30) and said imaging means (40).
The measuring system (200) according to any one of the preceding claims characterized in that said imaging means (40) comprise:
- a first (20;
- 420) and a second (400) converging imaging optical elements configured such that an image focus of one coincides with an object focus of the other at a second convergence point located in a second focusing plane (405) positioned between said first (20;
- 420) and second (400) converging imaging optical elements,
- said imaging means (40) being adapted to form an image of said sample (2) from said inspection beam (99) having interacted with said sample (2) on said matrix detection means (50).
The measuring system (200) according to the preceding claim characterized in that said imaging means (40) further comprise:
- a fourth selection optical element (45) having a fourth aperture surrounding said second convergence point.
The measuring system (200) according to the preceding claim, characterized in that said fourth aperture is positioned at the level of the image focus of said first imaging optical element (20;
- 420) and of the object focus of said second imaging optical element (400) so as to let pass essentially the portion of the light beam propagating parallel to the optical axis A.
The measuring system (200) according to any one of the three preceding claims characterized in that said Schlieren lens (20) replaces said first imaging optical element (420) along an optical path of said inspection beam (99) after the latter has interacted in reflection with said sample (2).
The measuring system according to any one of the preceding claims characterized in that said imaging means (40) are imaging means 4F such that:
- said first converging optical element (20;
- 420) is positioned between said Schlieren lens (20) and said fourth selecting means (45), so that its object focal plane coincides with a plane of said sample (2) and,
- said second converging optical element (400) is positioned between said fourth selecting means (45) and said matrix detection means (50), so that its image focal plane coincides with said matrix detection means (50).
Dependencies are inferred from the claim text.