Package for optical filter device
View Patent ↗An optical assembly includes a lens unit having a first lens and a second lens arranged on a common optical path with substantially coincident optical axes. Each lens has a transmission region through which light passes from a first side to a second side of the lens, and a first and a second table region on the periphery of the transmission region. The table regions are flat surfaces positioned on the first and second sides of each lens. An optical element holding tube is butt-coupled to the first table region of the first lens. An optical element, such as a filter, is supported on the first element holding tube. A second lens support tube holds the first lens and the second lens at opposite ends, with the first element holding tube therebetween. The first and second lenses and the optical element are passively aligned and then fixed in place with optical adhesive at the butt joints.
1. An optical assembly comprising:
a lens unit comprising:
a first lens and a second lens arranged on a common optical path with substantially coincident optical axes, each lens comprising:
a transmission region through which light passes from a first side to a second side of the lens, and
a first table region and a second table region on the periphery of the transmission region, said table regions comprising flat surfaces and positioned on a first and a second side of the lens;
a first support tube butted to the first table region of the first lens;
an optical element butted on said first support tube; and
a second support tube holding the first lens and the second lens at opposite ends thereof, with the first support tube therebetween,
said first and second lenses, and said optical element being passively aligned and fixed in place at the butt joints.
2. The optical assembly of claim 1 , wherein said first and second lenses, said first and second support tubes comprise thermally compatible glass compositions.
3. The optical assembly of claim 2 , wherein said glass compositions are transparent to radiation which will cure the adhesive.
4. The optical assembly of claim 3 , wherein a table region of each of said first and said second lenses abuts an end of said second support tube.
5. The optical assembly of claim 4 wherein said first support tube is bonded to said second support tube in an annular region between said first and said second support tubes.
6. The optical assembly of claim 5 wherein said optical element is a filter.
7. The optical assembly of claim 3 , wherein the second support tube surrounds said first and said second lenses.
8. The optical assembly of claim 7 wherein said first support tube is bonded to said second support tube in an annular region between said first and said second support tubes.
9. The optical assembly of claim 8 wherein said optical element is a filter.
10. The optical assembly of claim 7 , further comprising an input ferrule butt coupled to a first end of the second support tube, and an output ferrule butt coupled to the output end of the second support tube.
11. The optical assembly of claim 3 , further comprising an input ferrule butt coupled to a table region of said first lens, and an output ferrule butt coupled to a table region of said second lens.
12. The optical assembly of claim 1 wherein each of the first and the second lens is an aspheric molded lens.
13. The optical assembly of claim 1 further comprising a first fiber pigtail adhesively bonded to a first end of the lens unit, and a second fiber pigtail adhesively bonded to the second end of the lens unit.
14. A method of assembling an optical package comprising:
mounting an optical element on a first endface of a first tube;
mounting a first lens on a second endface of the first tube;
inserting the optical element and first tube into a second tube;
mounting the first lens to an end of the second tube; and
mounting a second lens to the opposite end of the second tube.
15. The method of claim 14 further comprising passively optically aligning said first lens and said optical element.
16. The method of claim 15 wherein the mounting of the first lens and the second lens to endfaces of the second tube includes applying an adhesive at the joints between the first and second lens and the first and second endfaces, respectively, and curing said adhesive.
17. The method of claim 16 further comprising: aligning a fiber pigtail to each of the first and second lenses, and mounting the fiber pigtails thereto.