The mechanism of vision, most precious of senses, has long fascinated philosophers and scientists: one of the earliest explanations was offered by Pythagoras in the sixth century BCE. Two thousand years later, a burst of activity in lens science led to the development of telescopes, enhancing the innate capability of observation at a distance. Eventual recognition that there is a vast electromagnetic spectrum, of which our eyes register a minute sliver, opened the gates further to remote sensing, enabling the detection of objects visibly obscured by distance, or by intervening scattering and absorption.
Pulsed lasers paved the way for adding the dimension of time, and the birth of lidar technology. Pulse lengths and the speed of ancillary time-of-flight-detection circuitry originally limited applications to remote targets. Spectroscopic analysis of the signals from such devices provide valuable information on remote chemical species and concentrations, as in studies of clouds or industrial atmospheres. A more recent revolution, leading to extensive use in transportation and autonomous vehicles, is possible due to advances in pulsing, scanning, and array-detection technology, alongside the miniaturization of components and AI implementation. Such developments, which can interpret the field of indirectly scattered light, even provide a basis to locate and identify objects around corners.
The science of lenses and imaging has progressed with no less vigor, as our smartphones testify. Another development is drones' capability to stream high-quality images and data. Applications are rife, ranging from security and defense deployments to agricultural crop inspection. Such tools become still more powerful when combined with multispectral imaging, facilitating analytical inspections of critical transportation infrastructure. All around, our world is being transformed by access to visual information from vantage points far beyond human reach. The applications highlighted in this issue of Photonics Focus showcase the achievement, progress, and future promise of this field.
If all of optics and photonics is in essence an extension of human vision, let us not forget the amazing precision instrument that is the eye itself. Here too, optical technology impinges on us, and not just in the correction lenses worn by more than half the adults in developed countries. For example, the use of optical coherence tomography is now prevalent for monitoring retinal structure-a prospect first established and discussed in an SPIE paper 35 years ago. Yet, though their innate acuity and dynamic range is astonishing, our eyes are more than soft cameras; in many ways they are entirely matchless. Even with the best kit available as we interact remotely in the COVID world, nothing replaces the subtleties conveyed in eye-to-eye contact. Roll on the day when we shall once again see each other in fully human form, and not just through a glass, darkly.
 |
David Andrews 2021 SPIE President |
