Subwavelength imaging challenges in the infrared and THz wavebands

Subwavelength imaging has recently seen increased interest in multiple fields. There are various applications and distinct contexts for performing subwavelength imaging. The technological ways to proceed as well as the benefits obtained are as various as the applications foreseen. To benefit from subwavelength imaging a way around standard imaging procedure is often required. INO is also involved in this activity mainly for the infrared and the THz wavebands. In the infrared band a detector with 17 um pixel pitch, larger than the pixel, was used in conjunction with a microscanning device to oversample the image at a pitch much smaller than the wavelength. In this case the pixel size is in the order of the wavelength but the sampling is at subwavelength level. In the THz band a 35 um pixel pitch is used at wavelength ranging from 70 um to 1,063 mm to perform imaging through various objects. In this case, the pixel itself is smaller than the wavelength. Subwavelength imaging is not without its challenges, though. For instance, while the use of ultra-fast optics provides better definition, their design becomes more challenging as the models used are at their very limits. Questions about information content of images can be raised as well. New research avenues are being investigated to help address the challenges of subwavelength imaging with the goal of achieving higher imaging system performance. This paper discussES aspects to be considered, review some results obtained and identify some of the key issues to be further addressed