A novel mid‐infrared transmission imaging (MIR‐TI) technique for the nondestructive, optical inspection of yttria‐stabilized tetragonal zirconia polycrystal (Y–TZP) components is described. This technique was designed specifically for the detection of flaws and cracks within the bulk of the ceramic component. The MIR‐TI technique exploits a transparency window in Y–TZP from 3 to 7 μm; at shorter wavelengths the material is highly scattering, while at longer wavelengths it is absorbing. We demonstrate that using this technique it is possible to detect micrometer‐scale flaws at depths of up to 6 mm.
We report the application of optically immersed,
room-temperature InSb/InAlSb LED and photodiode devices to the
ppm-level detection of nitrogen dioxide (NO2) at a
wavelength of 6 µm. The LED emission and the photodiode
detectivity are both increased by the optical immersion,
resulting in a power dissipation of only 0.25 mW in the LED. A
White cell is used for high gas sensitivity and its relatively
small numerical aperture can be conveniently matched to the
field of view of the hyperspherically immersed devices.
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