A new approach for confocal hyperspectral sensing based on the combination of a diffractive optical element and a tunable membrane fluidic lens is demonstrated. This highly compact lens system is designed to maximize the longitudinal chromatic aberration and select a narrow spectral band by spatial filtering. Changing the curvature of the fluidic lens allows the selected band to be scanned over the whole given spectrum. A hybrid prototype with an integrated electro-magnetic micro-actuator has been realized to demonstrate the functionality of the system. Experimental results show that the spectrum transmitted by the system can be tuned over the entire visible wavelength range, from 450 to 900 nm with a narrow and almost constant linewidth of less than 15 nm. Typical response time for scanning the spectrum by 310 nm is less than 40 ms and the lens system shows a highly linear relationship with the driving current.

We present a compact hyperspectral imaging system consisting of a combined refractive-diffractive optical element for extended longitudinal chromatic aberration, which provides spectrally resolved information of an object. This fully integrated hybrid device features a diffractive optical element (DOE) acting as a positive lens, a tunable concave liquid-filled membrane lens, and integrated magnetic actuation for hydraulically tuning the focal length of the membrane lens. The lens system is demonstrated to generate a hyperspectral data cube in the visible wavelength range by imaging the light from a pinhole array in a confocal approach onto a CCD camera.

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