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Why would THz waves offer higher resolution in imaging that IR? I understood that the shorter the wave, the higher the (lower bound on) attainable resolution?

Why would THz waves offer higher resolution in imaging that IR? I understood that the shorter the wave, the higher the (lower bound on) attainable resolution? Also, unrelated but no point in commenting twice: millimetre wave astronomy is a big topic of the last decade or two. How does the THz technology described here link to what's used in mm wave detection?

was_a_dev 4y ago
> It beats infrared light for resolving power because it suffers less Rayleigh scattering, imaging details less than 1 millimetre wide. While the wavelength of THz is larger than IR, and hence leads to a worse spatial resolution due to diffraction. This comment is about the scattering of light through a medium, which acts as a low pass filter leading to loss of higher spatial frequencies and therefore lower spatial resolution. > millimetre wave astronomy is a big topic of the last decade or two. How does the THz technology described here link to what's used in mm wave detection? They are effecitevely the same band (1mm ~ 0.3THz). The difference between astronomy and other applications is photon flux. Distant astronomical objects are faint, therefore detection methods only need to detect a small number of photons/s. One popular detector is cryogenic bolometers, which measure a temperature increase due to absorbed energy from a THz photon. These work well in low-flux applications.
adrian_b 4y ago
I do not know if this claim is true, but in the article it is said that infrared light imaging is affected by Rayleigh scattering, which limits its resolution. According to this claim, many common materials would diffuse the infrared light so that the image would look like looking to something through translucent glass or through fog, which would diminish the resolution. I assume that this refers to imaging through visually opaque materials, i.e. through clothes, like for airport security, not to looking through the air with an infrared camera.

was_a_dev 4y ago

> It beats infrared light for resolving power because it suffers less Rayleigh scattering, imaging details less than 1 millimetre wide. While the wavelength of THz is larger than IR, and hence leads to a worse spatial resolution due to diffraction. This comment is about the scattering of light through a medium, which acts as a low pass filter leading to loss of higher spatial frequencies and therefore lower spatial resolution. > millimetre wave astronomy is a big topic of the last decade or two. How does the THz technology described here link to what's used in mm wave detection? They are effecitevely the same band (1mm ~ 0.3THz). The difference between astronomy and other applications is photon flux. Distant astronomical objects are faint, therefore detection methods only need to detect a small number of photons/s. One popular detector is cryogenic bolometers, which measure a temperature increase due to absorbed energy from a THz photon. These work well in low-flux applications.

adrian_b 4y ago

I do not know if this claim is true, but in the article it is said that infrared light imaging is affected by Rayleigh scattering, which limits its resolution. According to this claim, many common materials would diffuse the infrared light so that the image would look like looking to something through translucent glass or through fog, which would diminish the resolution. I assume that this refers to imaging through visually opaque materials, i.e. through clothes, like for airport security, not to looking through the air with an infrared camera.