US-20260126343-A1 - OPTICAL FIBER ENDFACE INSPECTION MICROSCOPE NATIVELY ADAPTED FOR ANGLED POLISHED CONNECTORS

US20260126343A1US 20260126343 A1US20260126343 A1US 20260126343A1US-20260126343-A1

Abstract

There is provided an optical-fiber connector endface inspection microscope device that is natively designed for inspecting angled-polished (APC) optical-fiber connectors, i.e., without requiring an angled adapter tip or optical components in the adapter tip to deviate light reflected from the optical-fiber endface. Adapter tips are still needed to adapt the microscope device to different types of connectors, but they are small, straight, and low cost. This can be achieved using optics configured to deviate the illumination path so illumination light exits the inspection microscope device along an illumination path that is at an angle that is substantially egal to 8 degrees, so as to illuminate the connector endface in a direction that is substantially normal to the angled-polished endface to be inspected.

Inventors

Jean Filion
Raphael LABERGE
OLIVIER COTE
Mario L'Heureux

Assignees

EXFO INC.

Dates

Publication Date: 20260507
Application Date: 20250415

Claims (20)

1 . An optical-fiber connector endface inspection microscope device for inspecting an endface of an angled-polished optical-fiber connector, the optical-fiber connector endface inspection microscope device comprising: an illumination source generating illumination light for illuminating the endface to be inspected, said illumination light propagating along an illumination path; an image detector for capturing at least one image of the endface to be inspected from light returned from the endface; an objective lens system comprising at least one objective lens to produce an image of the endface to be inspected on the image detector, the objective lens system defining an optical axis; relay optics receiving said illumination light for illuminating the connector endface, and configured to deviate said illumination path so as to illuminate the connector endface in a direction that is substantially normal to the angled-polished connector endface to be inspected; and a housing structure enclosing said illumination source, said image detector, said objective lens system and said relay optics, said housing structure being releasably connectable to an adapter tip for mechanically interfacing with the angled-polished optical-fiber connector so as to position an optical-fiber axis of the angled-polished optical-fiber connector substantially parallel to the optical axis of said objective lens system; and wherein illumination light exits said housing structure along an illumination path that is at an angle of about 8 degrees relative to the optical axis of said objective lens system, so as to illuminate the connector endface in a direction that is substantially normal to the angled-polished endface to be inspected.
2 . The optical-fiber connector endface inspection microscope device as claimed in claim 1 , wherein said housing structure comprises a main housing and an optical head connectable to the main housing; wherein the optical head is releasably connectable to an adapter tip for mechanically interfacing with the optical-fiber connector to be inspected and defining a position of the connector endface on an object plane for inspection; and wherein said relay optics are enclosed in the optical head.
3 . The optical-fiber connector endface inspection microscope device as claimed in claim 2 , wherein the adapter tip is interchangeable with other adapter tips to allow inspection of various types of optical-fiber connectors, whereas the optical head remains the same for said multiple types of optical-fiber connectors to be inspected.
4 . The optical-fiber connector endface inspection microscope device as claimed in claim 2 , wherein said optical head comprises a substantially elongated hollow member and a sub-cell assembly in which said relay optics are assembled, said sub-cell assembly being mounted within the elongated hollow member.
5 . The optical-fiber connector endface inspection microscope device as claimed in claim 1 , wherein said relay optics comprises: a first relay lens and a second relay lens along said illumination path and receiving said illumination light from said objective lens system, said first relay lens and said second relay lens deviating said illumination path to an angle of about 8 degrees relative to the optical axis of said objective lens when illumination light exits said relay optics.
6 . The optical-fiber connector endface inspection microscope device as claimed in claim 1 , wherein said relay optics comprises: a first relay lens and a second relay lens along said illumination path and receiving said illumination light from said objective lens system; and a first refracting plane surface and a second refracting plane surface in-between said first relay lens and second relay lens, wherein said first refracting plane surface and said second refracting plane surface are both tilted relative to optical axes of said first relay lens and second relay lens so as to deviate said illumination path at an angle that is substantially egal to 8 degrees relative to the optical axis of said objective lens system when said illumination light exits said relay optics.
7 . The optical-fiber connector endface inspection microscope device as claimed in claim 6 , wherein optical axes of said objective lens system, said first relay lens and second relay lens are substantially parallel to an optical fiber axis of said angled-polished optical-fiber connector during inspection.
8 . The optical-fiber connector endface inspection microscope device as claimed in claim 7 , wherein optical axes of said objective lens system and of said first lens and second relay lens are all substantially aligned to a center of the connector endface during inspection.
9 . The optical-fiber connector endface inspection microscope device as claimed in claim 6 , wherein said relay optics comprise a first optical wedge and a second optical wedge along said illumination path, wherein a surface of said first optical wedge defines said first refracting plane surface and a surface of said second optical wedge defines said second refracting plane surface.
10 . The optical-fiber connector endface inspection microscope device as claimed in claim 6 , wherein said relay optics comprise an optical prism, said optical prism defining said first refracting plane surface and said second refracting plane surface.
11 . The optical-fiber connector endface inspection microscope device as claimed in claim 1 , wherein said angle of said illumination path at the exit of said housing structure relative to the optical axis of said objective lens is between 6 and 10 degrees.
12 . The optical-fiber connector endface inspection microscope device as claimed in claim 11 , wherein said angle of said illumination path at the exit of said housing structure relative to the optical axis of said objective lens is between 7 and 9 degrees.
13 . The optical-fiber connector endface inspection microscope device as claimed in claim 1 , wherein the objective lens system further comprises a reflective device between the at least one objective lens and the relay optics to deflect said optical axis, and wherein illumination light exits said housing structure along an illumination path that is at an angle of about 8 degrees relative to the deflected optical axis.
14 . An optical-fiber connector endface inspection microscope system for inspecting an endface of an angled-polished optical-fiber connector, the optical-fiber connector endface inspection microscope system comprising: an optical-fiber connector endface inspection microscope device comprising: an illumination source generating illumination light for illuminating the endface to be inspected, said illumination light propagating along an illumination path; an image detector for capturing at least one image of the endface to be inspected from light returned from the endface; an objective lens system comprising at least one objective lens to produce an image of the endface to be inspected on the image detector; relay optics receiving said illumination light for illuminating the connector endface, and configured to deviate said illumination path so as to illuminate the connector endface in a direction that is substantially normal to the angled-polished connector endface to be inspected; and a housing structure enclosing said illumination source, said image detector, said objective lens system and said relay optics, said housing structure being releasably connectable to an adapter tip for mechanically interfacing with the angled-polished optical-fiber connector; wherein illumination light exits said housing structure along an illumination path that is at an angle of about 8 degrees relative to an optical axis of said objective lens system; and wherein said housing structure comprises a main housing and an optical head connectable to the main housing, said relay optics being enclosed in the optical head; and an adapter tip releasably connectable to the optical head, for mechanically interfacing with the optical-fiber connector to be inspected and configured to position the connector endface on an object plane for inspection such that an optical fiber axis of said optical-fiber connector is substantially parallel to optical axis of said objective lens system and so as to illuminate the connector endface in a direction that is substantially normal to the angled-polished endface to be inspected.
15 . The optical-fiber connector endface inspection microscope system as claimed in claim 14 , wherein the adapter tip is interchangeable with other adapter tips to allow inspection of various types of optical-fiber connectors, whereas the optical head remains the same for said multiple types of optical-fiber connectors to be inspected.
16 . The optical-fiber connector endface inspection microscope system as claimed in claim 14 , wherein said relay optics comprises: a first relay lens and a second relay lens along said illumination path and receiving said illumination light from said objective lens system; and a first refracting plane surface and a second refracting plane surface in-between said first relay lens and second relay lens, wherein said first refracting plane surface and said second refracting plane surface are both tilted relative to optical axes of said first relay lens and second relay lens so as to deviate said illumination path at an angle that is substantially egal to 8 degrees relative to the optical axis of said objective lens system when said illumination light exits said relay optics.
17 . The optical-fiber connector endface inspection microscope system as claimed in claim 16 , wherein optical axes of said objective lens system, said first relay lens and second relay lens are substantially parallel to an optical fiber axis of said angled-polished optical-fiber connector during inspection.
18 . The optical-fiber connector endface inspection microscope system as claimed in claim 17 , wherein optical axes of said objective lens system and of said first lens and second relay lens are all substantially aligned to a center of the connector endface during inspection.
19 . The optical-fiber connector endface inspection microscope system as claimed in claim 16 , wherein said relay optics comprise a first optical wedge and a second optical wedge along said illumination path, wherein a surface of said first optical wedge defines said first refracting plane surface and a surface of said second optical wedge defines said second refracting plane surface.
20 . The optical-fiber connector endface inspection microscope system as claimed in claim 14 , wherein the objective lens system further comprises a reflective device between the at least one objective lens and the relay optics to deflect said optical axis, and wherein illumination light exits said housing structure along an illumination path that is at an angle of about 8 degrees relative to the deflected optical axis.

Description

TECHNICAL FIELD The present description generally relates to inspection of optical-fiber connector endfaces, and more particularly to optical-fiber connector endface inspection microscopes adapted to inspect angled-polished optical-fiber connectors. BACKGROUND The quality and cleanliness of endfaces of optical-fiber connectors represent important factors for achieving adequate system performance of optical communication networks. Indeed, any contamination of or damage on the mating surface of an optical-fiber connector may severely degrade signal integrity. Optical-fiber inspection microscopes are commonly employed to visually inspect and/or to analyze the optical-fiber endface of an optical-fiber connector at installation or during maintenance of optical communication networks, in order to verify the quality of the optical-fiber connection. Because of the wide variety of optical-fiber connector types deployed in the telecommunication industry, optical-fiber connector endface inspection microscopes are typically employed with interchangeable adapter tips so as to allow inspection of various types of optical-fiber connectors directly or as inserted in an optical-fiber connector adapter. Optical-fiber connector endface inspection microscopes are therefore typically designed for use with an adapter tip selected among a plurality of adapter tip types. Optical-fiber connectors now used in the industry can be split angled-polished physical-contact (APC) or non-angled-polished physical-contact (UPC). Conventionally, existing optical-fiber connector endface inspection microscopes are natively designed for inspecting non-angled-polished (UPC) optical-fiber connectors. Angled-polished (APC) optical-fiber connectors may be inspected using special adapter tips designed to support such connectors. As shown in FIG. 1A, adapter tips designed for inspecting non-angled-polished (UPC) optical-fiber connectors may consist of simple mechanical adapters. They are made straight and typically comprise no optical component. They can thus be manufactured at relatively low cost. In order to appropriately image the optical-fiber endface, illumination light reflected from the endface should be appropriately collected by the inspection microscope. This typically necessitates that the imaging axis of the inspection microscope system be aligned perpendicularly to the inspected endface. Therefore, as shown in FIG. 1B, adapter tips designed for inspecting angled-polished (APC) optical-fiber connectors are inevitably more complex. An 8-degree angle is manufactured in the adapter tip in order to position the angled-polished (APC) connector so as to align the imaging axis of the inspection microscope system perpendicularly to the inspected endface. The manufacturing process of such adapter tip substantially impact the cost when compared to adapter tips for non-angled-polished connectors (i.e., about three times the cost of a UPC adapter tips). However, this alignment can become impractical, e.g., when inspecting an angled-polished physical-contact (APC) optical-fiber endface that is deeply recessed within an optical-fiber connector adapter, especially when it is long and narrow, or when the connector is in a densely populated patch panel. Optical elements such as lenses, wedges and/or rhomboid prisms may then be included in the adapter tip in order to allow such inspection. For example, some fiber inspection adapter tips exist in the art for imaging deeply recessed APC connector enfaces. For example, U.S. Pat. No. 9,880,359 to Morin-Drouin et al. describes a fiber inspection adapter tip using at least one relay lens within the tip. In this case, the inspection microscope may be positioned so its optical axis is parallel to the optical fiber axis of the inspected connector. The lens axis of the relay lens is offset relative to the optical-fiber endface so as to deviate light reflected from the optical-fiber endface, towards the optical axis of the inspection microscope. Also, U.S. Pat. No. 11,644,625 to Filion et al. describes a fiber inspection adapter tip using a rhomboid prism to relay light reflected from the optical-fiber endface to the optical axis of the inspection microscope. These special adapter tips are even more expensive due to manufacturing complexity and the additional cost of the optical components, and significantly impact the overall cost of the solution, especially if multiple expensive adapter tips are needed to support a variety of optical-fiber connectors deployed in the field. There therefore remains a need for an optical-fiber connector endface inspection microscope solution that allow inspection of angled-polished (APC) optical-fiber connectors at lower cost. SUMMARY It was found that, nowadays and especially in the broadband access market, most optical-fiber connectors are made angled-polished (APC). There is therefore an increased need for a low-cost solution for inspection of angled-polished (APC) optical-fiber conn