Collimating lens having doublet element between positive-power elements
First Claim
1. A collimating lens assembly having an optical axis and comprising:
- a first lens group disposed along said optical axis at a first end of said assembly;
a second lens group disposed along said optical axis at a second end of said assembly opposite said first end;
a doublet lens element disposed along said optical axis between said first lens group and said second lens group;
wherein said first lens group and said second lens group each comprise at least one singlet positive-power optical lens element;
wherein said doublet lens element includes a first negative-power lens element and a second positive-power lens element, said first lens element having a higher index of refraction than said second lens element for chromatic correction of said collimating lens; and
wherein said assembly is operative to form a telecentric pupil along said optical axis external to said second end of said assembly.
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Accused Products
Abstract
A collimating lens (10) is constructed of a lens assembly having a first lens set (12, 14) at a first end of the assembly and a second lens set (20) at a second end of the assembly with a doublet (16, 18) disposed between the first lens set and the second lens set. The first lens set includes a plurality of lens elements (12, 14) each of which has positive optical power. The second lens set has a single lens element (26) of positive optical power and a concave surface (40) facing subject matter to be viewed by the collimating lens. The doublet lens element includes a lens element (16) constructed of flint glass and having a negative optical power plus a lens element (18) constructed of crown glass and having a positive optical power. In the doublet lens element, the negative power lens element has two concave surfaces, the positive-power lens element has two convex surfaces, and the two lens elements are cemented together to provide for a broad-band chromatic correction. The second end of the optical assembly of the lens is characterized by a telecentric entrance pupil for the viewing of a radiant subject. An external aperture stop (50) is provided in front of the first end of the optical assembly at a distance of at least one focal length from the first lens element of the collimating lens. This provides for more efficient collection of light and a wider field of view.
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Citations
17 Claims
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1. A collimating lens assembly having an optical axis and comprising:
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a first lens group disposed along said optical axis at a first end of said assembly; a second lens group disposed along said optical axis at a second end of said assembly opposite said first end; a doublet lens element disposed along said optical axis between said first lens group and said second lens group; wherein said first lens group and said second lens group each comprise at least one singlet positive-power optical lens element; wherein said doublet lens element includes a first negative-power lens element and a second positive-power lens element, said first lens element having a higher index of refraction than said second lens element for chromatic correction of said collimating lens; and wherein said assembly is operative to form a telecentric pupil along said optical axis external to said second end of said assembly. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A collimating lens assembly having a first end and a second end opposite said first end, said lens assembly comprising:
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a first group including first and second positive-power singlets having a first index of refraction, said first group being located at said first end of said assembly; a third positive-power singlet located at said second end of said assembly, said third singlet also having said first index of refraction; and a doublet disposed between said first group and said third singlet, said doublet including a positive-power lens having an index of refraction less than said first index, and a negative-power lens having an index of refraction greater than said first index wherein said assembly is operative to form a telecentric pupil along said optical axis external to said second end of said assembly. - View Dependent Claims (9, 10)
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11. A system comprising:
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an optical display; a collimating lens assembly having opposing first and second ends, said first end being in optical communication with said display, said assembly including a first lens group located at said first end of said assembly and a second lens group located at said second end of said assembly, said first and second groups each including at least one positive-power singlet, said assembly further including a doublet disposed between said first and second groups; and scanning means, in optical communication with said second end of said assembly, for scanning said display. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification