Optical fiber endface inspection with optical power measurement

There is provided an optical-fiber connector endface inspection microscope system comprising optical power measurement capability, wherein optical power measurement is provided via an optical power meter device implemented within an extension unit positioned along an optical path between the inspected optical-fiber connector endface and the optical-fiber connector endface inspection microscope, i.e. between the inspected optical-fiber connector endface and objective optics of the optical-fiber connector endface inspection microscope.

TECHNICAL FIELD

The present description generally relates to optical-fiber connector endface inspection, and more particularly, to optical-fiber connector endface inspection microscopes comprising both optical power measurement and connector endface inspection capabilities.

BACKGROUND OF THE ART

The quality and cleanliness of endfaces of optical-fiber connectors represent important factors for achieving expected 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 connector endface inspection microscopes are commonly employed to inspect the 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.

Some optical-fiber inspection microscope probes also include a separate power detection port which allows the operator to measure the optical power of light exiting the optical-fiber connector. The operator is required to sequentially connect the optical-fiber connector under inspection to the inspection microscope port and to the power detection port. Of course, additional handling of optical-fiber connectors increases the risk of potential contamination of the connector endface.

U.S. Pat. No. 8,908,167 to Flora et al. proposes an optical-fiber inspection microscope configuration that includes an integrated optical power measurement assembly such that endface inspection and power measurement may be conducted using the same port.

U.S. Pat. No. 9,915,790 to Baribault proposes an optical-fiber inspection microscope configuration that includes an integrated optical power measurement assembly, and which is suitable for both angularly-polished (e.g. FC/APC) and perpendicularly-polished (e.g. FC/PC) optical-fiber connectors.

The configurations of both Flora et al. and Baribault require the optical-fiber inspection microscope to be originally designed to accommodate optical power measurement capabilities.

Although existing optical-fiber inspection microscope probes are satisfactory to a certain degree, there remains room for improvement, particularly in terms of providing a fiber inspection microscope system comprising a optical power measurement function.

SUMMARY

Accordingly, in accordance with one aspect, there is provided an optical-fiber connector endface inspection microscope system comprising optical power measurement capability, wherein optical power measurement is provided via an optical power meter device implemented within an extension unit positioned along an optical path between the inspected optical-fiber connector endface and the inspection microscope, i.e. between the inspected optical-fiber connector endface and objective optics of the inspection microscope.

Positioning the optical power meter device outside of the imaging system of the inspection microscope advantageously allows optimization of the optical design of the optical power measurement assembly without affecting the optical design of the imaging assembly of the inspection microscope, which is optimized for connector endface inspection. As will be understood, the optical spectrum of light used in endface inspection (referred to herein as the inspection light beam) is different from the optical spectrum of light of which the optical power is to be measured (referred to herein as the signal light beam). Because the focal length of lenses typically varies with wavelength, objective optics of the inspection microscope has different focal lengths for the signal light beam and the inspection light beam. The objective optics and the focusing function of the inspection microscope is not optimized for capturing and focusing the signal light beam (the imaging assembly is configured to focus the inspection light beam on the image sensor, not the signal light beam). Redirecting or otherwise splitting the signal light beam from the inspection light beam before it reaches objective optics of the optical-fiber connector endface inspection microscope allow better optimization of the signal light beam capture and focusing on the optical power detector. Furthermore, if the signal light beam were to pass through the objective optics and focusing function, its focus on the optical power detector would be caused to vary, thereby causing variability in the optical power measurement responsivity. Redirecting or otherwise splitting the signal light beam before it reaches the objective optics obviates this issue as a whole. Minimizing the number of optical components through which the signal light beam passes also provides better stability in optical power measurement responsivity.

In some embodiments, the optical power meter device is releasable from the optical-fiber connector endface inspection microscope. Such configuration may advantageously allow an existing inspection microscope without optical power measurement capability to be converted into a system having integrated optical power measurement capability such that both endface inspection and optical power measurement may be conducted using a common connection port, without modifying the existing optical-fiber connector endface inspection microscope. In some embodiments, the optical power meter extension unit can be retrofitted to inspection microscopes that are already in possession of customers or end users without any need to return the existing inspection microscope to manufacture or maintenance. A releasable optical power meter device may also advantageously allow an inspection microscope to be used either with or without the optical power measurement capability, depending on user needs. In some further embodiments, the optical power meter extension unit may be configured to be also usable as a standalone device, i.e., without an inspection microscope, in order to measure optical power measurement only.

In accordance with one aspect, there is provided an optical power measurement device for use with an optical-fiber connector endface inspection microscope having, at an inspection end, objective optics defining an object plane, comprising:

a housing structure comprising: a first end connectable toward an optical-fiber connector endface to be inspected; and a second end toward the inspection end of said optical-fiber connector endface inspection microscope;

an imaging path within said housing structure between said first end and said second end along which an inspection light beam reflected from the connector endface propagates toward the second end;

a relay lens system along the imaging path, comprising at least a first converging optics at said first end, said relay lens system producing an image of the optical-fiber connector endface to be inspected on an object plane of the optical-fiber connector endface inspection microscope;

an optical power detector; and

beam redirection optics disposed along the optical imaging path between the optical-fiber connector endface to be inspected and objective optics of said optical-fiber connector endface inspection microscope, said beam redirection optics being configured to split at least part of light exiting the optical-fiber connector endface from the inspection light beam to direct the at least part of light exiting the optical-fiber connector endface toward said optical power detector.

In accordance with one aspect, there is provided an optical-fiber connector endface inspection microscope and optical power measurement system, comprising:

an optical-fiber connector endface inspection microscope having objective optics at an inspection end; and

optical power measurement device comprising:

a housing structure comprising: a first end connectable toward an optical-fiber connector endface to be inspected; and a second end toward the inspection end of said optical-fiber connector endface inspection microscope;

an imaging path within said housing structure between said first end and said second end along which an inspection light beam reflected from the connector endface propagates toward the second end;

a relay lens system along the imaging path, comprising at least a first converging optics at said first end, said relay lens system producing an image of the optical-fiber connector endface to be inspected on an object plane of the optical-fiber connector endface inspection microscope;

an optical power detector; and

beam redirection optics disposed along the optical imaging path between the optical-fiber connector endface to be inspected and objective optics of said optical-fiber connector endface inspection microscope, said beam redirection optics being configured to split at least part of light exiting the optical-fiber connector endface from the inspection light beam to direct the at least part of light exiting the optical-fiber connector endface toward said optical power detector.

In some embodiments, said housing structure may be releasably connectable to a microscope housing of the optical-fiber connector endface inspection microscope via said second end. Such configuration may advantageously allow an existing optical-fiber connector endface inspection microscope without optical power measurement capability to be converted into a system having integrated optical power measurement capability, without modifying the existing optical-fiber connector endface inspection microscope.

In some embodiments, said first end of said housing structure may be releasably connectable to a connector-mating interface tip adapted to connect to an optical-fiber connector endface to be inspected. The connector-mating interface tip allows the optical-fiber connector endface inspection microscope and optical power measurement device to be used for a variety of configurations of optical-fiber connectors such as, e.g., LC/PC, LC/APC, SC/PC, SC/APC or FC/APC connectors as known in the art.

In some embodiments, said housing structure may be releasably connectable to a microscope housing of the optical-fiber connector endface inspection microscope via said second end; said first end of said housing structure may be releasably connectable to a connector-mating interface tip adapted to connect to an optical-fiber connector endface to be inspected; and said connector-mating interface tip may be releasably connectable to said inspection end of the optical-fiber connector endface inspection microscope in absence of the optical power measurement device. Such configuration allows an existing optical-fiber connector endface inspection microscope configured to be used with interchangeable connector-mating interface tips, to be converted into a system having integrated optical power measurement capability which may also be used for a variety of configurations of optical-fiber connectors via either an existing set of connector-mating interface tips or a similar set of connector-mating interface tips.

In some embodiments, said optical power detector may be disposed within said housing structure.

In some embodiments, said optical power detector may be external to said housing structure and said optical power measurement device may further comprise an optical waveguide connected to said housing structure, and coupling optics disposed within said housing structure and configured to couple said at least part of light exiting the optical-fiber connector endface to said optical waveguide.

In some embodiments, a magnification factor associated with said relay lens system may be 1×.

In some embodiments, said relay lens system may further comprise second converging optics at said second end.

In some embodiments, the optical-fiber connector endface inspection microscope may comprise an imaging assembly comprising said objective optics and an image detector, the imaging assembly being configured to illuminate the optical-fiber connector endface and to image the illuminated endface on said image detector for inspection thereof.

In accordance with another aspect, there is provided a method for inspecting an optical-fiber connector endface and measuring an optical power of light the same, the method comprising: connecting an optical power measurement device between an inspection end of an optical-fiber connector endface inspection microscope and a connector-mating interface tip; connecting an optical-fiber connector endface to be inspected to said connector-mating interface tip; defining an imaging path within a housing structure of the optical power measurement device, between said optical-fiber connector endface and objective optics of said optical-fiber connector endface inspection microscope, to convey an inspection light beam reflected from the connector endface toward said objective optics; producing an image of the optical-fiber connector endface to be inspected on the object plane of the optical-fiber connector endface inspection microscope via a pair of converging lenses; capturing an image of the optical-fiber connector endface via the optical-fiber connector endface inspection microscope, for inspection thereof; splitting at least part of light exiting the optical-fiber connector endface from the inspection light beam to direct the at least part of light exiting the optical-fiber connector endface toward an optical power detector, via a beam redirection element disposed along the optical imaging path between the optical-fiber connector endface to be inspected and said objective optics of said optical-fiber connector endface inspection microscope; and determining an optical power value of said light exiting the optical-fiber connector endface from an output of the optical power detector.

For ease of reading, in the following description, the “optical-fiber connector endface inspection microscope” and the “optical-fiber connector endface inspection microscope system” may be referred to respectively as an “inspection microscope” and an “inspection microscope system”. Similarly, the “optical power measurement device” may be referred to as a “power measurement device” or simply “PM device”; the “optical-fiber connector endface” may be referred to as a “connector endface” or simply “endface”; and the “connector-mating interface tip” may be referred to as an “interface tip” or simply a “tip”.

In this specification, unless otherwise mentioned, word modifiers such as “substantially” and “about” which modify a value, condition, relationship or characteristic of a feature or features of an embodiment, should be understood to mean that the value, condition, relationship or characteristic is defined to within tolerances that are acceptable for proper operation of this embodiment in the context its intended application.

Other features and advantages of the present description will become more apparent upon reading of the following non-restrictive description of specific embodiments thereof, given by way of example only with reference to the appended drawings.

In the present description, the terms “light” and “optical” are used to refer to radiation in any appropriate region of the electromagnetic spectrum. More particularly, the terms “light” and “optical” are not limited to visible light, but can include, for example, the infrared wavelength range. For example, in some embodiments, the light exiting the connector endface can have a wavelength spectrum lying somewhere in the range from about 850 nm to about 1625 nm; and the illumination source can be embodied emit light in the blue region, e.g., at about 470 nm, or any other suitable spectral region within the visible spectrum, the near ultraviolet spectrum or the near infrared spectrum. Those skilled in the art will understand, however, that these wavelength ranges are provided for illustrative purposes only and that the present techniques may operate beyond these ranges.

It should also be understood the when the appended drawings are denoted as schematics, elements of the drawings are not necessarily drawn to scale. Some mechanical or other physical components may also be omitted in order to not encumber the figures.

In the following description, similar features in the drawings have been given similar reference numerals and, to not unduly encumber the figures, some elements may not be indicated on some figures if they were already identified in a preceding figure. It should be understood herein that the elements of the drawings are not necessarily depicted to scale, since emphasis is placed upon clearly illustrating the elements and structures of the present embodiments.

The following description is provided to gain a comprehensive understanding of the methods, apparatus and/or systems described herein. Various changes, modifications, and equivalents of the methods, apparatuses and/or systems described herein will suggest themselves to those of ordinary skill in the art. Description of well-known functions and structures may be are omitted to enhance clarity and conciseness.

Although some features may be described with respect to individual exemplary embodiment, aspects need not be limited thereto such that features from one or more exemplary embodiment may be combinable with other features from one or more exemplary embodiments.

DETAILED DESCRIPTION

Optical connectors normally need to be inspected when they are connected and disconnected from one another. Typically, the procedure involves sequential steps of measuring an optical power value using an optical power detector and visually inspecting the optical-fiber connector endface using a fiber inspection microscope. However, undesirable particles can be deposited on the endface of the optical fiber while manipulating the optical fiber from the fiber inspection probe to the optical power detector, for instance. To circumvent this drawback, some have proposed fiber inspection probes adapted to inspect optical-fiber connector endfaces, which would incorporate both an optical-fiber endface imaging assembly and an optical power detection assembly. Such inspection probes would allow performing the two steps mentioned above in a single step, thus reducing the risk of contamination. However, such solutions imply a redesign of the existing inspection microscopes in order to introduce power measurement capabilities along the inspection path. The following disclosure describes an optical power measurement device that can be permanently or releasably attached to an inspection microscope to provide both connector endface inspection capability and power measurement capability on a common connection port, without requiring modification to the inspection microscope configuration, including its optical design (location and properties of lenses, mirrors, beamsplitters, illumination source, photodetectors, etc.) and its mechanical design (translation stages, fixtures, etc.) which, when coupled to a fiber inspection microscope and power measurement probe, allows inspection of connectors, as well as power measurement.

FIG. 1Ashows a schematic side view of a prior art inspection microscope system100comprising an inspection microscope10and a connector-mating interface tip12connectable to an inspection end15of the inspection microscope10, in accordance with prior art inspection microscopes. As known in the art and as shown inFIG. 1B, the interface tip12is releasably connectable to the inspection microscope10via a connection mechanism13, and is typically interchangeable with other connector-mating interface tips in order to adapt the connector-mating interface14of the inspection microscope system100to different configurations of optical-fiber connectors such as, e.g., LC/PC, LC/APC, SC/PC, SC/APC or FC/APC connectors or bulkhead adapters as known in the art, by mechanically engaging with the connector16or a bulkhead adapter in which lies an optical-fiber connector endface18(seeFIG. 1B) to be inspected. The connector16typically has a ferrule end (not shown) that is perpendicular to a propagation axis20of one or more optical fibers (not shown). The connector endface18coincides with the ferrule end. The inspection end15of an inspection microscope herein generally refers to the end of an inspection microscope that is adapted to receive the connector endface18for optical magnification thereof, by connecting directly (i.e. mechanical engagement) or indirectly (e.g. via an interface tip) with an optical-fiber connector or bulkhead adapter to be inspected.

FIG. 1Bshows a schematic side view of the inspection microscope system100in which the connector-mating interface tip12and the connector16are shown disconnected from the inspection microscope10. The interface tip12can be disconnected from the inspection microscope10by opening the connection mechanism13.

FIG. 1Cshows a schematic side view of an embodiment of an optical-fiber connecter endface inspection microscope system200that is configured to provide both optical power measurement and connector endface inspection capabilities. The inspection microscope system200comprises the optical-fiber connector endface inspection microscope100, the connector-mating interface tip12and an optical power measurement device22that is embodied as an extension unit24releasably connectable between the inspection end15of the inspection microscope10and the interface tip12.

In the embodiment ofFIG. 1C, the inspection microscope system200advantageously integrates an existing optical-fiber connector endface inspection microscope and connector-mating interface tip but it will be understood that, in other embodiments, the optical power measurement device22may be made to be combined with redesigned inspection microscopes and interface tips, depending on the commercial application. The optical power measurement device22may also be made permanently attached to an inspection microscope.

The power measurement device22has a generally elongated hollow housing structure26having a first end28connectable toward an optical-fiber connector endface18to be inspected and a second end30connectable toward the inspection end15of the optical-fiber connector endface inspection microscope. An imaging path32is defined within the housing structure26between the first end28and the second end30to convey an image of the connector endface18toward the inspection end15of the inspection microscope10.

In the embodiment ofFIG. 1C, the housing structure26indirectly connects toward the connector endface18via the interface tip12. The interface tip12releasably connects to the housing structure26and the housing structure26releasably connects to the inspection microscope10via corresponding connection mechanisms13that are both equivalent or compatible to that interconnecting interface tip12to the inspection microscope10, so that the optical power measurement device22can be seamlessly inserted between the inspection microscope10and the interface tip12.

It will be understood that, in other embodiments, the interchangeable tips can be omitted to connect the connector endface18directly to the optical power measurement device22, for example, if the optical power measurement device22is made for specific use with a single one or a limited number of connector configurations. As such, the first end28of the housing structure may be either releasably connectable to the connector or bulkhead adapter to be inspected or releasably connectable to an interface tip12.

Also, in other embodiments, the optical power measurement device22may be made permanently attached to or integrated into the inspection microscope10.

As will be understood, the following description applies equivalently to single-fiber and multi-fiber connectors made to interconnect either single-mode or multimode fibers. The inspection microscope system200can be adapted to receive such different configurations of optical-fiber connectors by connecting the corresponding connector-mating interface tip12.

FIGS. 2 to 10are schematic views of various examples of the optical configuration of the inspection microscope system200ofFIG. 1C.

Now referring toFIG. 2, there is shown a schematic side view of an example of an optical configuration of the inspection microscope system200ofFIG. 1Ccomprising an optical-fiber connector endface inspection microscope10and an optical power measurement device22. In this figure as well as inFIGS. 3 to 11, the interface tip12, the housing structure26, the connection mechanisms13as well as other mechanical and electronic components are omitted in order not to encumber the figures.

As will be understood by one skilled in the art, the inspection microscope10incorporates an imaging assembly40comprising an illumination source42for illuminating the connector endface18to be inspected, an illumination beam splitter43to direct illumination light toward the connector endface18, an image sensor50, and imaging optics, including an objective lens44(and optionally other lenses, mirrors and/or other optical components defining objective optics), for imaging the illuminated connector endface18located on an object plane46of the inspection microscope10, on an image plane48coinciding with the image sensor50. The object plane46as defined herein is determined by the objective lens44and, in absence of the optical power measurement device22, coincides with the plane where the connector endface18to be inspected (i.e. the object) should be positioned (within the focusing range of the imaging assembly40) to be suitably imaged on the image plane48. The optical path between the object plane46and the image plane48defines an imaging path52of the inspection microscope, along which propagates the inspection light beam56resulting from a reflection of illumination light on the connector endface18, for optical magnification of the object (i.e. the connector endface18) positioned on the object plane46.

Optionally, the imaging assembly40may further comprise aberration controlling optics54to correct any potential aberrations cause by propagation of the inspection light beam56across the illumination beam splitter43.

Typically, a wavelength of the illumination beam is relatively short in order to enhance the imaging resolution (since the diffraction limit is proportional to the wavelength) while keeping a wavelength that can be measured using commercially available image sensors which are both cost- and size-accessible, such as a complementary metal-oxide-semiconductor (CMOS) sensor or a charge-coupled device (CCD), for instance. For example, the illumination source42can be embodied in a light-emitting diode (LED) emitting in the blue region, e.g. at about 470 nm. Indeed, such a blue light allows for an acceptable imaging resolution while being easily measured using conventional CMOS sensors or CCDs. Of course, other illumination sources and/or any other suitable spectral region within the visible spectrum, the near ultraviolet spectrum or the near infrared spectrum can be found suitable depending on the available components.

The optical power measurement device22acts on both the inspection light beam56, which corresponds to the light beam caused by the reflection of illumination light on the connector endface18and which is in the field of view of the image sensor50, and the signal light beam57which corresponds to light exiting the optical fiber(s) via the connector endface18and detected by the optical power detector68. It comprises a relay lens system58to relay inspection light beam56toward the inspection microscope10and a power detection assembly60, an output signal of which can be used to determine an optical power level of the signal light beam57.

The relay lens system58is positioned along the imaging path32and is used to elongate the overall imaging path32,52of the inspection microscope system200in order to accommodate the power detection assembly60therealong. Thanks to the relay lens system58, the connector endface18that should normally be positioned on the object plane46of the inspection microscope10for proper imaging, can be positioned away from the inspection end15of the inspection microscope10, on an object plane62of relay lens system58. In use, the relay lens system58produces on the object plane46of the inspection microscope10, an image (real or virtual) of the connector endface18positioned on the object plane62of the relay lens system58(to within a focusing range of the imaging assembly40).

The relay lens system58may be embodied by first converging lens64, or other converging optics (such as multiple lenses, complex lens(es), mirror(s) or any combination thereof), at the first end28of the housing structure26(seeFIG. 1C) and a second converging lens66, or other converging optics, at the second end30of the housing structure26.

Optionally, the relay lens system58may produce a magnification of 1× in order not to change the image produced on the image sensor50, but different magnification factors can be envisaged depending on the desired result.

Although other configurations may be envisaged, optionally, light exiting the connector endface18may be collimated between the first converging lens64and the second converging lens66in order to ease its propagation toward the optical power detector68. The inspection light beam56may or may not be collimated.

The power detection assembly60comprises an optical power detector68for measuring the optical power value of light exiting the connector endface18and beam redirection optics70disposed along the imaging path32, between the connector endface18and objective lens44of the inspection microscope10, and more specifically between the first converging lens64and the second converging lens66.

Beam redirection optics70comprises one or more optical elements used to split at least part of light exiting the connector endface18from the inspection light beam to direct the at least part of light exiting the optical-fiber connector endface toward the optical power detector68. It may be embodied by a power beam splitter (e.g., a 50/50 power beam splitter that separates light into two similar light beams), a dichroic beam splitter (by use of a dichroic coating) or a movable mirror that is either toggled in and out of the optical path or reoriented to direct the light beam toward a different direction.

The optical power measurement device22can be designed to operate either simultaneously with the inspection microscope10or in a sequential manner. If operated in the simultaneous manner, illumination and imaging of the endface18as well as optical power measurement are performed at the same time. As may be apparent to one skilled in the art, in the case of simultaneous measurements, a dichroic beam splitter may be used to separate the inspection light beam56returning from the connector endface18from the signal light beam57, so as to avoid stray portions of the inspection light beam56giving rise to power measurement bias, for instance. Indeed, in this case, dichroic beam splitters can separate light associated with the optical telecommunication range (e.g. about 850 nm to 1625 nm) from light associated with the illumination range (e.g. about 380 nm to 700 nm). For example, a dichroic beam splitter may be used to transmit illumination light and corresponding inspection light beam56, i.e. light associated with the illumination range (e.g. about 380 nm to 700 nm), and reflect light associated with the optical telecommunication range (e.g. about 850 nm to 1625 nm). Indeed, beam redirection optics70may be used to transmit illumination light from the illumination source42along the imaging path32and toward the connector endface18, and split the returning inspection light beam56from the signal light beam57, to direct them, respectively, to the inspection microscope10and to the optical power detector68. Of course, it will be understood that, in other configurations such as, e.g., that ofFIG. 3, transmission and reflection ranges may be interchanged.

If operated in a sequential manner, the imaging of the illuminated endface38is performed prior to or after the optical power measurement in a manner that does not necessitate the separating optics to have dichroic coating deposited thereon. In other words, the illumination source is shut off so that there is no illumination while measuring the optical power value associated with the tilted light. It is noted that optional anti-reflection coatings can be used irrespective of the manner of operation, i.e. simultaneous or sequential.

The optical power detector68is a photodetector suitable for measuring the optical power level of the signal light beam57. Photodetectors generate an analog electrical current, which is to be converted into a digital optical power measurement value using a power measurement circuit (not shown inFIG. 2). As known in the art, the optical power detector68can be selected to detect light associated with the optical telecommunication range (e.g. about 850 nm to 1625 nm). More specifically, a detection range including wavelengths from about 1310 to 1625 nm will cover most singlemode applications. A detection range from about 850 to 1300 nm will cover most multimode applications. Of course, smaller ranges, e.g. around 1310 nm, 1550 nm, 850 nm or 1300 nm may cover more specific applications. Example of suitable technologies of photodetectors include Indium Gallium Arsenide (InGaAs) and germanium photodetectors.

It is understood that the spectral content of the imaging beam and of the signal light beam can vary depending on commercial applications.

A converging lens72, or other converging optics, may be placed upstream from the optical power detector68to direct the signal light beam57on the surface of the optical power detector68. Of course, other lenses, mirrors or other optical elements may be added along the optical path of the signal light beam to redirect, focus or otherwise act on the signal light beam before detection. As known in the art, in some embodiments, compensating optics and/or polarization diverse optical power detection may be added to compensate or overcome polarization dependent responsivity.

The power measurement circuit may comprise an amplification circuit, an analog-to-digital conversion circuit and a memory. The power measurement circuit can either be integrated in the housing structure26of the optical power measurement device22(see, e.g.,FIG. 8), integrated within the housing of inspection microscope10(see, e.g.,FIG. 9) or be built into a physically separate module. As described herein below, the optical power detector68may also be either integrated in the housing structure26, in the housing of the inspection microscope10or built into a physically separate module (seeFIG. 10).

Depending on the configuration of the optical power measurement device22, the disposition of the relay lens system58and the power detection assembly60may vary, as described herebelow inFIGS. 3 to 5.

Now referring toFIG. 3, there is shown a schematic side view of another example of an optical configuration of an optical power measurement device122along with the inspection microscope10ofFIG. 2. In the optical power measurement device122, the first end28of the optical power measurement device122is oriented at a 90-degree angle relative to its second end30to receive the connector16or bulkhead adapter at a 90-degree angle relative to the orientation expected by the inspection microscope10. Apart from the herein-noted differences, the optical power measurement device122is similar to the optical power measurement device22ofFIG. 2and like features are not be repeatedly described.

The optical power measurement device122comprises a relay lens system158to relay inspection light beam56toward the inspection microscope10and a power measurement assembly160to determine an optical power level of the signal light beam57. The relay inspection light beam56comprises a first converging lens164at the first end28and a second converging lens166at the second end30. The power detection assembly60comprises an optical power detector168for measuring the optical power value of light exiting the connector endface18and beam redirection optics170disposed along the imaging path132, between the connector endface18and the objective lens44of the inspection microscope10, and more specifically between the first converging lens164and the second converging lens166. The beam redirection optics170is configured to redirect at a 90-degree angle, via reflection, illumination light received at the second end30, toward the first end28, whereas the signal light beam57is transmitted through the beam redirection optics170toward the optical power detector168. It will be appreciated that although the mechanical disposition of the elements is different, the functions achieved by the optical power measurement device122ofFIG. 3are the same as that of the optical power measurement device22ofFIG. 2.

Now referring toFIG. 4, there is shown a schematic side view of another example of an optical configuration of an optical power measurement device222along with the inspection microscope10ofFIG. 2. In optical power measurement device222, the orientation of the first end28is parallel with the second end30and the inspection end15of the inspection microscope10but is offset relative to the second end30. Apart from the noted differences, the optical power measurement device222is similar to the optical power measurement device22ofFIG. 2and like features are not be repeatedly described.

The beam redirection optics270ofFIG. 3comprises a mirror274positioned at a 45-degree angle relative to the imaging path232to deflect the imaging path232towards the first end28. As inFIG. 3, the beam redirection optics270is configured to redirect at a 90-degree angle, via reflection, illumination light received at the second end30, toward the first end28, whereas the signal light beam57is transmitted through the beam redirection optics270toward the optical power detector268. It will be understood that the orientation of the mirror274may vary and that various other configurations and orientations of mirror(s) may be used to redirect the imaging path232towards any required position and/or orientation of the first end28relative to the second end30. Furthermore, depending on the desired configuration, the mirror274or multiple mirrors may be oriented so that an orientation of the connector16relative to the inspection microscope10not be in the same plane.

Now referring toFIG. 5, there is shown a schematic view of another example of an optical configuration of an optical power measurement device322along with the inspection microscope10ofFIG. 2. In optical power measurement device322, a relay lens system358comprises a single converging lens364. In this case, to accommodate a minimum distance to insert a beam redirection optics370, a focal point of the inspection light beam56may be located inside the optical power measurement device322. The single converging lens364may produce an image of the optical-fiber connector endface to be inspected at the focal point which corresponds to the object plane of the optical-fiber connector endface inspection microscope. Apart from the noted differences, the optical power measurement device322is similar to the optical power measurement device22ofFIG. 2and like features are not be repeatedly described.

It will be appreciated that although the mechanical disposition of the elements inFIGS. 3 to 5are different, the functions achieved by the optical power measurement devices122,222and322ofFIGS. 3, 4 and 5, respectively, are the same as that of the optical power measurement device22ofFIG. 2.

One skilled in the art will understand that some additional electronic components that are not illustrated inFIGS. 2 to 11may be required to operate the inspection microscope and the optical power measurement device. Electronic components that are commonly known in the art of inspection microscope are not discussed herein and it is considered implicit that the inspection microscope may include, for example, an integrated or separate display (e.g., via a dedicated viewing device or via a generic computing device such as a personal computer, a tablet or a smart phone), an integrated or separate processing module (e.g., in a dedicated viewing device or a generic computing device such as a personal computer, a tablet or a smart phone) and one or more communication modules such as, e.g., Bluetooth, Wi-Fi and/or Universal Serial Bus (USB).

Power measurement results obtained via the optical power measurement device22,122,222or322may be either displayed directly on a display or pass/fail indicators (e.g. LED indicators) provided on the extension unit24(seeFIG. 1), communicated to the inspection microscope10for analysis and/or display or communicated to a separate device (e.g., a dedicated viewing device or a generic computing device such as a personal computer, a tablet or a smart phone), for analysis, display or other output to a user.

The optical power detector68or168generates an analog electrical signal, which needs to be converted into a digital optical power measurement value using a power measurement circuit. It will be understood that such power measurement circuit may comprise an amplification circuit, an analog-to-digital conversion circuit and a memory, as known in the art. Various examples of electric configurations of the optical power measurement device are described with reference toFIGS. 6 to 9.

FIG. 6shows a schematic side view of an embodiment of an inspection microscope system in which an optical power measurement device422comprises a power measurement circuit476and a display478, both embedded in the extension unit24of the optical power measurement device422, such that power measurement values are made readily viewable by a user on the extension unit24.

FIG. 7shows a schematic side view of another embodiment of an inspection microscope system in which the optical power measurement device522comprises a power measurement circuit576and a wireless communication module580(such as Bluetooth, Wi-Fi, Radio Frequency (RF) and/or infrared) embedded in the extension unit24of the optical power measurement device522. The wireless communication module580serves to communicate measured power measurement values to the inspection microscope10or to a separate display device582(e.g., a dedicated display device or a generic computing device such as a personal computer, a tablet or a smart phone for instance) via a corresponding communication module584, for display and optional analysis or other output to a user.

In a variant of the embodiment ofFIG. 7(not shown), the wireless communication between the power measurement circuit576and the inspection microscope10may be replaced by a wired communication via a cable connection between the power measurement circuit576and the inspection microscope10.

FIG. 8shows a schematic side view of another embodiment of an inspection microscope system in which a power measurement circuit678is embedded in the housing of the inspection microscope10. In this case, an optical power measurement device622comprises an optical power detector68and the analog electrical current from the optical power detector68is electrically conveyed to the power measurement circuit678via an electrical connection680. The analog electrical current from the optical power detector68is remotely converted into a digital optical power measurement value via the power measurement circuit678embedded in the inspection microscope10.

FIG. 9shows a schematic side view of yet another embodiment of an inspection microscope system comprising an optical power measurement device722in which the signal light beam57is coupled into an optical waveguide786such as a single-mode or a multimode optical fiber or any other light guide, for remote detection in a separate device782comprising an optical power detector768and a power measurement circuit778. The optical power measurement device722comprises coupling optics772, such as, e.g., a gradient-index (GRIN) lens, to capture the signal light beam57and inject it into a cut end of the optical waveguide786. Light is propagated to the separate device782where it exits the optical waveguide786toward the optical power detector768. The optical power measurement device722ofFIG. 9has the advantage of not requiring electrification of the extension unit24.

It will be understood that the embodiments ofFIGS. 2 to 8may require electrical power to be supplied to the extension unit24. Such power may be provided by an onboard battery which may be rechargeable, e.g., via a releasably connectable cable, or replaceable. In another embodiment, the inspection microscope10may supply power to the extension unit24via, e.g., a cable or electrical contacts between the inspection microscope10and the extension unit24.

The inspection microscope systems and optical power measurement devices described herein with reference toFIGS. 1 to 9may be used to measure the optical power of light exiting both non-angled polished and angled-polished connectors. It will be understood that the endface of a non-angled polished optical-fiber connector causes light propagating in the optical fiber(s) to exit the connector endface in a diverging signal light beam57of which the mean propagation direction is perpendicular to the connector endface18(i.e. in continuity with the propagation axis of the optical fiber(s)). The connector endface of an angled polished optical-fiber connector has an angled ferrule end that is not perpendicular to the propagation axis of the optical fiber(s). A connector-mating interface tip adapted for angled-polished optical-fiber connectors typically has a mating interface that is configured such that the angle-polished endface would be perpendicular to an imaging path32of the inspection microscope10in order to suitably image the connector endface. An angle-polished connector endface causes a mean propagation direction of the signal light beam57exiting the endface to be tilted relative to both the propagation axis of the optical fiber(s) and the imaging path32of the inspection microscope10. In some embodiments, a significant portion of the signal light beam57may not reach the relay lens system of the power measurement device. In this case, a lens can be provided in the interface tip12, as described in U.S. Pat. No. 9,915,790, hereby incorporated by reference, to capture the signal light beam57and direct it toward the relay lens system.

Now referring toFIG. 10, there is shown a schematic side view of another example of an inspection microscope system comprising an extension unit824which comprises two imaging ports to allow imaging of two optical fiber connectors. The extension unit824comprises the relay lens system58as described hereinabove and an beam splitter843inserted along the imaging path32between the first converging lens64and the second converging lens66of the relay lens system58in order to allow imaging of two optical fiber connectors either simultaneously or sequentially.

The extension unit824has a first imaging port828and a second imaging port829to respectively receive the patch panel connector816and the loose connector817. The beam splitter843is used to split the imaging path52into two imaging paths852a,852bto image both connectors. A second relay lens system58bis comprises the second converging lens66and a third converging lens64b.

In one embodiment, a single connector is mated to the extension unit824at a time to prevent the superimposition on the image sensor50of images from the two endfaces. In another embodiment, the beam splitter843is replaced by a movable mirror. Toggling between the two imaging ports828,829may be provided by flipping the movable mirror in and out of the imaging path52to redirect it toward either the first imaging port828or the second imaging port829.

Prior to mating two connectors, their respective endfaces should be inspected. One of the two connectors to be mated is typically recessed in a patch panel and accessible via a bulkhead adapter, where the other is the end of a patch cord connector that is to be inserted in the bulkhead adapter for connection to the patch panel. Prior art optical-fiber connector endface inspection microscopes are configured to inspect a single endface at a time. As such, inspection of both connectors to be together mated is performed by either alternately connecting each connector to the inspection microscope or by using two separate inspection microscopes. A drawback of the alternate connection method is that the two connectors do not have the same mechanical configuration (one is a loose connector and the other is recessed in a patch panel). A different interface tip12(seeFIG. 1) is therefore required for each connector, requiring additional manipulation to change the interface tip12between inspections. Switching tips can be a lengthy operation and may cause tip loss issues. The configuration ofFIG. 10can advantageously use a single device to inspect both connectors (loose/patch cord and patch panel).

FIG. 11shows a schematic side view of another embodiment of an inspection microscope system in which an optical power measurement device922combines the optical power measurement device22ofFIG. 2with the two-port extension unit824ofFIG. 10. Along the imaging path52, the optical power measurement device922comprises a beam splitter943that splits the imaging path52toward the two imaging ports928,929, as well as a power measurement assembly960comprising an optical power detector68and beam redirection optics70.

The embodiments described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the appended claims.