An apparatus for detecting an optical signal emission from a plurality of signal emission sources, comprising: a plurality of signal transmission fibers each comprising a plurality of cores having a first spatial core arrangement at a first end and a second spatial core arrangement at a second end that is the same as the first spatial core arrangement, each first end being configured to be optically coupled to a respective signal emission source, and each fiber being configured to transmit an optical signal emitted between the first end and the second end; a frame assembly securing the first ends of the plurality of signal transmission fibers in a first spatial fiber arrangement corresponding to a spatial arrangement of the signal emission sources, and securing the second ends of the plurality of signal transmission fibers in a second spatial fiber arrangement different from the first spatial fiber arrangement; at least one signal detector located at the second end of at least one of the plurality of signal transmission fibers whereby the signal detector is configured to detect an optical signal emitted by each signal emission source; the signal detector comprising an excitation light source for transmitting light to the first end of at least one of the plurality of signal transmission fibers; and a camera system configured to: acquire an image of an intensity pattern of light emitted by the at least one signal detector and transmitted from the first end of at least one of the plurality of signal transmission fibers to a second end of the at least one of the plurality of signal transmission fibers, and determine whether the acquired image of the intensity pattern of the transmitted optical signal is symmetric or asymmetric. a plurality of signal transmission fibers each comprising a plurality of cores having a first spatial core arrangement at a first end and a second spatial core arrangement at a second end that is the same as the first spatial core arrangement, each first end being configured to be optically coupled to a respective signal emission source, and each fiber being configured to transmit an optical signal emitted between the first end and the second end; a frame assembly securing the first ends of the plurality of signal transmission fibers in a first spatial fiber arrangement corresponding to a spatial arrangement of the signal emission sources, and securing the second ends of the plurality of signal transmission fibers in a second spatial fiber arrangement different from the first spatial fiber arrangement; at least one signal detector located at the second end of at least one of the plurality of signal transmission fibers whereby the signal detector is configured to detect an optical signal emitted by each signal emission source; the signal detector comprising an excitation light source for transmitting light to the first end of at least one of the plurality of signal transmission fibers; and a camera system configured to: acquire an image of an intensity pattern of light emitted by the at least one signal detector and transmitted from the first end of at least one of the plurality of signal transmission fibers to a second end of the at least one of the plurality of signal transmission fibers, and determine whether the acquired image of the intensity pattern of the transmitted optical signal is symmetric or asymmetric.