Infrared holography using a microbolometer array

Abstract

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 10 W cw CO(2) 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.

Speckle interferometry at 10 micrometers wavelength: a combined thermography and interferometry technique and its application in aeronautical nondestructive testing

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Long-wave infrared digital holographic interferometry with diffuser or point source illuminations for measuring deformations of aspheric mirrors

“…The first experiments with DH in the LWIR range 7,8 used modern pyroelectric modified camera (no longer requiring light intensity variations) in Mach-Zehnder configuration for reconstructing small object images. The microbolometer array camera technology was then demonstrated for digital hologram recording by George et al 10 in a similar configuration. Since then, many works followed for the application of microbolometer arrays for the observation of large objects by DH.…”

Mobile speckle interferometer in the long-wave infrared for aeronautical nondestructive testing in field conditions

“…Digital holography (DH) with electronic hologram recording and numerical reconstruction was proposed 5,6 with modern pyroelectric modified camera (no longer requiring intensity variations) in the Mach-Zehnder configuration for reconstructing small object images. The microbolometer array camera technology was then demonstrated in DH by George et al 7 in a similar configuration. Since then, many works followed in the area of applying microbolometer arrays to observations of large objects by DH.…”