A Sensitive Infrared Imaging Upconverter and Spatial Coherence of Atmospheric Propagation
Theoretical reasoning has indicated that atmospheric “seeing” disturbances should allow sharper astronomical images at infrared than at visible wavelengths , yet imaging devices for astronomy have not generally been available at wavelengths beyond the near infrared. Planets and their atmospheric structure provide interesting subjects for infrared imaging systems , in either broad or narrow spectral regions. So do some more distant objects, such as stars surrounded by thick dust shells, which emit strongly in the infrared, and the nuclei of Seyfert galaxies. All of these objects can be spatially resolved in the larger astronomical telescopes, and hence are valuable subjects for infrared imaging. We describe here the exploration of an infrared imaging technique based on the nonlinear interaction known as upconversion . This technique was used to obtain images of several astronomical objects in the 10 Um spectral region, and to demonstrate quantitatively the sharper images allowed for wavelengths beyond the visible region.
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