An apparatus for processing an optical signal, the apparatus comprising: a light source configured to output a light; a first sensor array arranged two-dimensionally on an incident surface and comprising a plurality of first image sensors configured to obtain a first image signal by detecting the light that is scattered, reflected, or refracted from a target, wherein the plurality of first image sensors include a first reference sensor disposed at a predetermined position in the first sensor array, and the first reference sensor is covered by a metal so as to wholly or partially block the corresponding optical signal; a second sensor array arranged two-dimensionally on the incident surface in an area adjacent to the first sensor array, the second sensor array comprising a plurality of second image sensors configured to obtain a second image signal by detecting the light that is scattered, reflected, or refracted from the target, wherein the plurality of second image sensors include a second reference sensor disposed at a predetermined position in the second sensor array, and the second reference sensor is covered by a metal so as to wholly or partially block the corresponding optical signal; and a processor configured to determine a characteristic of the target based on an analysis result of the first image signal and the second image signal, wherein the processor is further configured to obtain and determine the first image signal and the second image signal based on the positions of the first reference sensor and the second reference sensor and to obtain the analysis result by comparing the first image signal to the second image signal; and wherein the processor is, in particular, further configured to determine offsets of the first image signal and the second image signal by using a signal obtained from the first reference sensor and a signal obtained from the second reference sensor, wherein the offset of the first image signal is a deviation of the overall signal value of the first image signal from the first reference signal and the offset of the second image signal is a deviation of the overall signal value of the second image signal from the second reference signal. a light source configured to output a light; a first sensor array arranged two-dimensionally on an incident surface and comprising a plurality of first image sensors configured to obtain a first image signal by detecting the light that is scattered, reflected, or refracted from a target, wherein the plurality of first image sensors include a first reference sensor disposed at a predetermined position in the first sensor array, and the first reference sensor is covered by a metal so as to wholly or partially block the corresponding optical signal; a second sensor array arranged two-dimensionally on the incident surface in an area adjacent to the first sensor array, the second sensor array comprising a plurality of second image sensors configured to obtain a second image signal by detecting the light that is scattered, reflected, or refracted from the target, wherein the plurality of second image sensors include a second reference sensor disposed at a predetermined position in the second sensor array, and the second reference sensor is covered by a metal so as to wholly or partially block the corresponding optical signal; and a processor configured to determine a characteristic of the target based on an analysis result of the first image signal and the second image signal, wherein the processor is further configured to obtain and determine the first image signal and the second image signal based on the positions of the first reference sensor and the second reference sensor and to obtain the analysis result by comparing the first image signal to the second image signal; and wherein the processor is, in particular, further configured to determine offsets of the first image signal and the second image signal by using a signal obtained from the first reference sensor and a signal obtained from the second reference sensor, wherein the offset of the first image signal is a deviation of the overall signal value of the first image signal from the first reference signal and the offset of the second image signal is a deviation of the overall signal value of the second image signal from the second reference signal.