A method for testing optical fibers includes using an optical testing instrument to measure a characteristic, such as clad non-circularity, of an optical fiber at a multiple angles of rotation of an optical fiber around its optical axis. From the measurements data points indicative of measured values of the characteristic at the respective angles of rotation are generated. A model is created of the optical fiber having the characteristic as a variable parameter, and from the model a functional relationship between an expected measured value of the characteristic and the angle of rotation and the variable parameter is generated. By varying the parameter a fit of the functional relationship to the data points is made according to one or more predetermined criteria, such as least-squares fit. The value of the characteristic can be found based on the fit. Instrumental parameters, such as fiber misalignment and cleave angle, can also be ascertained by the method.

In an optical fiber monitoring system which detects physical disturbance or other parameters such as temperature or strain of a fiber where a monitor signal is transmitted along the optical fiber and analyzed to detect changes which are indicative of an event, a method is provided for periodically checking proper operation of the optical fiber monitoring system. A fiber disturbance actuator periodically causes a pattern of disturbances of a portion of the fiber at a predetermined location thereon where the disturbance is characteristic of the event to be monitored. The monitor signal is analyzed to detect the pattern of changes and in the event that expected changes are not detected, a warning is issued that the intrusion detection system is not properly operating.

A device may use a camera to capture an image of an end face of an optical fiber in a field of view of the camera. The device may monitor a focus metric associated with the image while the image is manually focused using an opto-mechanical assembly. The device may automatically initiate a test to inspect the image of the end face of the optical fiber for compliance with a set of criteria related to cleanliness and damage based on the focus metric satisfying a condition. The device may output a result from the test indicating whether the end face of the optical fiber satisfies the set of criteria related to cleanliness and damage.

A method for adjusting brightness includes detecting whether damage occurs on a light guide plate of the display device, determining a damage position and a damage extent of the light guide plate when the damage occurs on the light guide plate, and compensating for a change value of brightness generated due to the damage by adjusting the brightness of the display device corresponding to the damage position, according to a predetermined correspondence between damage extents and change values of brightness. The method for testing a display device includes applying a destructive operation to the display device to be tested, detecting a damage extent generated by the destructive operation and a change value of brightness correspondingly generated in a damage region, and creating and storing a correspondence between the damage extent and the change value of brightness.

This application relates to methods and apparatus for fiber optic sensing which can provide information about the environment in which the fiber optic is deployed. In particular the application relates to fiber optic based sensing of the mechanical impedance of the environment. The method comprises using an interrogator (201) to interrogate an optical fiber (104) which is coupled to a first element (202; 802) which is responsive to electromagnetic fields. In use a varying electric current (I), which may be an alternating current, is applied so as to induce a varying force (F) on said first element. The optical radiation backscattered from within the optical fiber is analyzed to determine a measurement signal indicative of a variation in the backscattered radiation corresponding with said electric current applied. The first element may be a first conductor (202) and the varying current may be supplied to the first conductor, or to a second conductor (701). Alternatively the first element could be a magnetic element (802). By applying a variable force to the first element, and hence the optical fiber, the characteristics of the environment can be determined.

The output profile of light from a multimode optical fiber is determined using a geometrical optics approach where the rays launched into the fiber conform to LP-modes of the fiber. This output profile can then be employed as an input to a second fiber to calculate the transmission losses of a coupler that introduces various coupling inaccuracies, such as lateral offset, axial offset, and angular offset.

An optical sensor (100) comprises: a holding sleeve (11); a fixed ferrule (12) fixedly mounted in said holding sleeve (11); a movable ferrule (13) movably mounted in said holding sleeve (11), a predetermined distance existing between a first movable end of said movable ferrule (13) and a first fixed end of said fixed ferrule (12) in said holding sleeve (11); a reflection part (14) arranged at a second movable end of said movable ferrule (13) opposite to said first movable end, for reflecting light entering the movable ferrule (13); and an actuation part (15), said actuation part (15) being constructed to drive said movable ferrule (13) to move so that said first movable end moves towards said first fixed end. An optical sensor assembly and a monitoring device comprising the optical sensor (100), or another sensor (1012) can remotely detect a mechanical movement in a passive mode. A first reflector (14, 1016) is configured to provide a first reflected optical signal. The sensor (100, 1012) is connected to the first reflector and has a first position and a second position, the second position configured to attenuate the first reflected optical signal more than the first position. The sensor is configured to move between the first and second positions in response to a monitored parameter (1018).

An inspection device for an optical ferrule includes one or more reflectors. Each reflector has a mating surface and a mirror disposed at an oblique angle with respect to the mating surface. Each reflector is configured to mate with the optical ferrule when the optical ferrule is disposed within a housing of an optical connector. When the mating surface of the reflector is in mated contact with the mating surface of the optical ferrule, the mirror is positioned to provide a reflected view of at least a portion of a mating surface of the optical ferrule.

A portable inspection probe for the inspection of a recessed mating surface of an optical fiber connector is provided. In one variant, the portable inspection probe includes a digital holographic detection module operable to digitally record a hologram of the recessed mating surface, and a rigid probe tip configured to be optically coupled to the digital holographic detection module and shaped to provide optical access to the recessed mating surface. In another variant, the portable inspection probe is to be used with a rigid probe tip connectable thereto, and the digital holographic detection module includes a probing optical assembly not traversed by a reference beam and configured to direct an object beam onto the recessed mating surface and to collect the object beam upon reflection thereof by the recessed mating surface. An inspection system and an inspection method are also provided.

The disclosed technology includes, among others, methods and devices for measuring distributed fiber bend or stress related characteristics along an optical path of fiber under test (FUT) uses both a light input unit and a light output unit connected to the FUT at one single end.