An optical sensor array includes light-emitting devices and sensor heads remote from the light-emitting devices, and each light-emitting device is optically coupled to plural sensor heads through optical fibers; the light-emitting device is optically connected to the optical fibers by means of a multicore optical fiber connector, and the multicore optical fiber connector keeps the optical axes of the optical fibers equally spaced from the optical axis of the light-emitting device; even though the light intensity is isotropically dispersed on the cross section of the light beam, the total amount of light incident on each optical fiber is equal to the total amount of light incident on any one of the other optical fibers so that a strict calibration is not required for the optical sensor array.