We describe a series of experiments to demonstrate holography at far-infrared wavelengths using an uncooled microbolometer array. Simple interference patterns and Fresnel zone holograms are recorded with a laser illumination in a Mach–Zehnder interferometer setup. A sparse-sampling method is used to sample the hologram at a rate dependent on the bandwidth of the object wavefront rather than the carrier frequency. The samples are then used to reconstruct the complex object wavefront in the hologram plane, which is Fresnel backpropagated for image reconstruction. Uncooled microbolometer arrays are most commonly used in passive mode to image the thermal–blackbody radiation. Their technology has matured to include the wavelength range of far-infrared to submillimeter radiation. The use of microbolometers with active illumination for holography, as described in this paper, suggests their interesting future applications.
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