Although high-resolution remote sensing with optical synthetic aperture radar is discussed in Chapter 4 on defense, the ability to do high-resolution imaging at long ranges can have applications in areas other than for the military. Planet Earth videos37 used defense-developed equipment for what at the time was long-range imaging, so animals could be remotely observed in their natural habitat without the observation changing the animals’ behavior. In disaster scenarios, long-range imaging can help to plan relief activities.
The performance of astronomical telescopes and free-space laser communication systems is severely limited by the effects of atmospheric distortion. Similarly, in microscopy and retinal imaging, optical aberrations can prevent one from achieving diffraction-limited resolution. “Adaptive optics (AO) is a technology that is used to improve the performance of optical systems by reducing the effect of wavefront distortions. It works by measuring the distortions in a wavefront and compensating for them with a device that corrects the errors, such as a deformable mirror or a liquid-crystal array.”38 Tremendous advances continue to occur in the technology and applications of adaptive optics.39 For example, in the not-too-distant future, a patient may, after having cataract surgery, be able to have a personalized aberration-corrected lens implanted that would give the person better vision than she or he had been born with.40
The ultimate technical challenge in sensing is to be able to detect something even at very low levels or with very high specificity, such as trace concentrations of toxic pollutants in the atmosphere, a specific biochemical structure, vibrations on the fuselage or wings of an airplane in order to gain early indications of crack formation, or variations in Earth’s gravity to facilitate a search for oil or other hidden objects. Imaging is sensing as a function of location to obtain a spatial rendering of whatever is being sensed. The goal of metrology is to ensure that the output
38BBC News. 2011. “‘Adaptive Optics’ Come into Focus.” Available at http://www.bbc.co.uk/news/science-environment-12500626. Accessed May 29, 2012.
39BBC News. 2011. “‘Adaptive optics’ Come into Focus.”
40 Chris Dainty, Professor of Applied Optics, National University of Ireland, Galway. Communication to the committee. May 15, 2011.