Multiple rays (which are also referred to as "object lights") such as scattered lights and fluorescent lights emitted radially in a variety of directions from each bright point in a measurement area S1 enter an objective lens 12, where the multiple rays are converted into a parallel beam. Then, the parallel beam reaches a phase shifter 14. The parallel beam is reflected by both a reference mirror unit 15 and an oblique mirror unit 16 of the phase shifter 14, and the reflected beams pass through an imaging lens 18 to form an interference image on a light-receiving surface 20a of a detection unit 20. Since there is a continuous change of an optical path length difference between the multiple rays reflected by the reference mirror unit 15 and those reflected by the oblique mirror unit 16, the detection of the light intensity of the interference image on the light-receiving surface 20a enables an acquisition of the interferogram (the waveform of the change of imaging intensity) in which the light intensity continuously changes. By Fourier-converting the interferogram, spectral characteristics can be obtained which show the relative intensities for each wavelength of the lights emitted from one bright point of an object S to be measured.
