EP0240194A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Improvements in or relating to optical beam expanders
Assignee: Qioptiq Ltd
•
Filing: 1987-03-13
•
Granted: —
•
Expires: 2007-03-13
Abstract
Abstract An optical substantially afocal beam expander has a negative lens element (1) spaced from a positive lens element (2). The lens elements are of different materials with respective coefficients of refractive index change with respect to temperature such that the effect of a temperature change on one element is at least partially compensated by the effect of the temperature change on the other element. The beam expander is therefore substantially athermalised with respect to afocality.
Inventors
- 👤 John Malcolm Palmer
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 16:30
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/09; G02B27/0938; G02B27/095; G02B27/0955; G02B13/00; G02B13/14; G02B13/22
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
63 words
An optical substantially afocal beam expander having spaced negative and positive lens components employing different materials having respective refractive index changes with respect to temperature such that the effect of a temperature change on one component is at least partially compensated by the effect of the temperature change on the other component whereby the beam expander is substantially athermalised with respect to afocality.
Claim 2
Dependent Claim
63 words
An optical substantially afocal beam expander having spaced negative and positive lens components employing different materials having respective refractive index changes with respect to temperature such that the effect of a temperature change on one component is at least partially compensated by the effect of the temperature change on the other component whereby the beam expander is substantially athermalised with respect to afocality.
Claim 3
Dependent Claim
70 words
A beam expander according to Claim 1 comprising a lens element of negative power of a first material spaced from a lens element of positive power of a second material different from the first, in which the respective coefficients of refractive index change with respect to temperature of the first and second materials are related in a manner such that the beam expander is substantially athermalised with respect to afocality.
Claim 4
Dependent Claim
28 words
A beam expander according to Claim 2 in which the magnification and the refractive index coefficients of the two materials substantially satisfy (at a design temperature) the relationship:-
Claim 5
Dependent Claim
27 words
A beam expander according to Claim 3 in which the magnification and the constringences of the two materials additionally substantially satisfy (at the design temperature) the relationship:-
Claim 6
Dependent Claim
30 words
A beam expander according to any of Claims 2 to 4 in which said lens element of negative power is a back element of meniscus shape convex to the rear.
Claim 7
Dependent Claim
31 words
A beam expander according to Claim 5 in which said lens element of positive power is a front element of meniscus shape convex to the front or convex to the rear.
Claim 8
Dependent Claim
27 words
A beam expander according to any preceding claim for operation with infra-red radiation in which the materials of the lens components or elements are infra-red transmitting materials.
Claim 9
Dependent Claim
35 words
A beam expander according to any of Claims 2 to 6 for operation with thermal infra-red radiation of about 10 microns wavelength in which said first and second materials are germanium and zinc selenide respectively.
Claim 10
Dependent Claim
44 words
A beam expander according to Claim 8 in which said lens element of negative power has refracting surfaces R1 and R2 and said lens element of positive power has refracting surfaces R3 and R4 having radii of curvature and axial separations substantially as follows:-
Claim 11
Dependent Claim
44 words
A beam expander according to Claim 8 in which said lens element of negative power has refracting surfaces R1 and R2 and said lens element of positive power has refracting surfaces R3 and R4 having radii of curvature and axial separations substantially as follows:-
References Cited (Backward Citations)
US3817604A
Cited
GB1530066A
Cited
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.