Patent EP0336334B1 successfully refreshed from Google Patents.
EP0336334B1
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EP
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Polarizer with dielectric films
Assignee: Alcatel CIT SA
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Filing: 1989-04-03
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Granted: 1993-12-08
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Expires: 2009-04-03
Abstract
Abstract The invention relates in particular to polarizing light whose angle of incidence may vary substantially, e.g. over +/-10 DEG . A polarizing stack (22) constituted by dielectric layers (30, 31, 32, 33, 34, . . . ) is formed on an oblique face (4). It is in the form of a repetitive sucession of symmetrical sequences (30, 31, 40) each constituted by two half-thickness low refractive index layers (30, 40) on either side of a high refracture index layer (31). The invention is particularly applicable to polarizing the light emitted by a semiconductor laser.
Inventors
- 👤 Jacques Mouchart
- 👤 Jacqueline Begel
- 👤 Eugène Duda
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 13:28
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/28; G02B27/283
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
361 words
A dielectric layer polarizer for polarizing light having a predetermined wavelength, said polarizer comprising: inlet means (12) for forming or transmitting an incident beam which is constituted by said light and whose rays propagate along directions close to a predetermined direction of incidence; a transparent substrate (8) having a face (4) on the path of said incident beam, said face being oblique relative to said direction of incidence; and a polarizing stack formed on said oblique face and constituted by thin dielectric layers, said layers being first and second index polarizing layers presenting a first refractive index and a second refractive index for said light and following one another in alternation starting from said oblique face and having different thicknesses, with the succession of said layers being in the form of a periodic succession of base sequences, each of which is constituted by a plurality of thin dielectric layers alternating between said first and second indices, said sequences being identical to each other with respect to their indices and the thicknesses of the layers which constitute them; said direction of incidence forming an angle of incidence with the direction perpendicular to said oblique face and to said polarizing layers, said angle of incidence being situated in a plane of incidence and having a value relative to said wavelength and to said indices and thicknesses of the polarizing layers such that said polarizing stack separates said incident beam (16) into a transmitted beam (28) and a reflected beam (20) with crossed polarizations; said polarizer being characterized by the fact that said base sequence is a symmetrical sequence (30, 31, 40) constituted by one of said second index (31) polarizing layers having a second index optical thickness ne H , and two first index elementary layers (30, 40) situated on either side of said second index layer and having the same thickness which, when doubled, constitutes a first index optical thickness 2ne B , such that pairs of said first index elementary layers (40, 42) combine at each interface between two consecutive base sequences in order to form one of said first index polarizing layers (32) having a said first index optical thickness.
Claim 2
Dependent Claim
274 words
A polarizer according to claim 2, in which said first and second indices are low and high indices respectively, the polarizer being characterized in that a base thickness W is given in terms of a low index proportion P, by the equation: 1/W = 1.92 - 0.77P; said base thickness W comprising a total relative thickness W₁/W O and being equal to the ratio of the total optical thickness W₁ = 2ne B + ne H of said base sequence (30, 31, 40) divided by a reference thickness W O ; said low index proportion P being a relative proportion P₁/P O of the low index optical thicknesses deduced from the total proportion P₁ = 2ne B /[2ne B + ne H ] of the optical thicknesses 2ne B of said low index layers (30, 40) in the optical thickness [2ne B + ne H ] of said base sequence, and being equal to the ratio P₁/P O of said total proportion P₁ divided by a reference proportion P O ; said reference thickness W O and said reference proportion P O being defined on a reference polarizer which is one of said thin layer polarizers in which high index polarizing layer and said full thickness index polarizing layer are quarterwave layers for said light and for said angle of incidence A O , said reference thickness W O and said reference proportion P O being the total optical thickness [2ne BO + ne HO ] and the total proportion of the low index optical thicknesses 2ne BO /[2ne BO + ne HO ] , respectively, in said base sequence of said reference polarizer.
Claim 3
Dependent Claim
23 words
A polarizer according to claim 3, characterized by the fact that said low index proportion P lies in the range 0.8 to 1.5.
Claim 4
Dependent Claim
24 words
A polarizer according to claim 4, characterized by the fact that said angle of incidence A O lies in the range 20° to 70°.
Claim 5
Dependent Claim
110 words
A polarizer according to claim 2, in the form of a transparent block (2) in which said oblique face (4) and said polarizing stack (6) are embedded, said block comprising: an inlet face (12) substantially perpendicular to said direction of incidence (10) in order to constitute said inlet means transmitting said incident beam (16) into said block; a transmission outlet face (26) situated on the path of said transmitted beam (28); and a reflection outlet face (18) situated on the path of said reflected beam (20); at least one of said outlet faces (26, 18) being substantially perpendicular to said transmitted or reflected beam on whose path it is situated.
References Cited (Backward Citations)
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