Swelling of nerve fibers during the action potential was demonstrated by three different methods. Generation of a propagated nerve impulse in a crab nerve produced an outward movement of 50 to 100 angstroms of the nerve surfce and a rise in swelling pressure on the order of 5 dynes per square centimeter. In squid giant axons, the amplitude of the observed outward movement of the surface was small.

The size of infrared camera systems can be reduced by collecting low-resolution images in parallel with multiple narrow-aperture lenses rather than collecting a single high-resolution image with one wide-aperture lens. We describe an infrared imaging system that uses a three-by-three lenslet array with an optical system length of 2.3 mm and achieves Rayleigh criteria resolution comparable with a conventional single-lens system with an optical system length of 26 mm. The high-resolution final image generated by this system is reconstructed from the low-resolution images gathered by each lenslet. This is accomplished using superresolution reconstruction algorithms based on linear and nonlinear interpolation algorithms. Two implementations of the ultrathin camera are demonstrated and their performances are compared with that of a conventional infrared camera.

A nerve impulse travelling along a crustacean nerve was found to be accompanied by a small,rapid movement of the nerve surface.The movement was 10-20nm in amplitude and was concurrent with a rise in the"swelling pressure"of the order of 5mg/cm2 for a nerve bundle.Initiation of an action potential at the site of cathodal polarization was preceded by a small,slow mechanical change in the nerve fiber.Anodal polarization produced a large mechanical change of the opposite sign.Tetrodotoxin and procaine suppressed rapid mechanical changes.Several previous investigators suggested the existence of rapid mechanical changes in nerve fibers concomitant with the production of action potentials (KAYUSHIN and LYUDKOVSKAYA,1955;FRANK,1958;LETTVIN et al.,1962;HILL et al.,1977).The alleged rapid mechanical changes reported before signal averages became available were all very large and most of those findings could not be confirmed by subsequent investigators (SANDLIN et al.,1968;COHEN,1973). HILL et al.(1977)employed the laser interferometry method combined with signal averaging and reported that electric excitation of a crayfish nerve fiber induced a rapid reduction of the fiber diameter followed by a relaxation.The present paper describes the results of our demonstration of small and rapid mechanical changes in crab nerve fibers during action potentials by the use of both optical and mechano-electric methods.We found that there is a distinct upward movement of a light-reflecting target placed on the surface of a nerve when action potentials are generated by electric stimulation.Furthermore,we could demonstrate that this movement is produced by a transient swelling of the nerve fiber.Obviously,these rapid mechanical changes are totally unrelated to the slow mechanical changes (KORNAKOVA et al.,1947;HILL,1950;BRYANT and TOBIAS,1955)which are known to be produced cumulatively by a large number of action potentials.In the present paper,we deal exclusively with the results obtained by using

We describe a multiple-aperture long-wave infrared camera built on an uncooled microbolometer array with the objective of decreasing camera thickness. The 5 mm thick optical system is an f/1.2 design with a 6.15 mm effective focal length. An integrated image is formed from the subapertures using correlation-based registration and a least gradient reconstruction algorithm. We measure a 131 mK NETD. The system's spatial frequency is analyzed with 4 bar targets. With proper calibration, our multichannel interpolation results recover contrast for targets at frequencies beyond the aliasing limit of the individual subimages.