A compact spectroscopic imaging device consisting of a planar reflection grating lens, a probe fiber array, and a two-dimensional image sensor was proposed and discussed. Reflected or luminescent lights from a subject are coupled to the probe fibers, guided to fiber output ends, radiated into the air, diffracted by the grating lens with wavelength-dependent angle, and focused onto lines on the image sensor. Two-dimensional intensity distribution on the image sensor can give one-dimensional spectrum distribution along a specified direction. A grating lens was designed with a fiber array and a CCD image sensor for 100-nm wavelength range and 10-mm fiber array width. A spectral resolution of 5 nm and a spatial resolution of 0.25 mm were experimentally confirmed.

Planar grating lens, fiber array and two-dimensional image sensor were assembled and packaged to be a compact spectroscopic imaging unit. Phase shift function of grating, end position of each fiber and image sensor tilt angle were optimized for suppressing aberration. Spatial resolution of 0.3 mm and spectral resolution of 5 nm were obtained with 100 nm spectral range. Size of the fabricated unit was 65×50×45 mm3.

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