We have developed a high-speed, electro -optic camera that features a large format; eight frames; and an accompanying eight -pulse, ruby laser illuminator.This system offers greater resolution and versatility than has been previously available. The eight 75 -mm frames provide high dynamic spatial resolution (15 line pairs /mm) and time resolution (as short as 10 -ns exposure time) to record fine physical details of rapid events.Four independent two -frame (tube) cameras complete with objective optics comprise the eight -frame array. Finally, pulsed ruby laser illumination with spectral filtering allows photography in intense ambient light.
A damage site camera was developed to record the onset of bulk laser damage in materials. The camera images and magnifies the damage track using forward-scattered laser light. Employing this camera we can detect the presence of very small (<10 μm) damage sites with densities as low as 10/cc. The camera is used at oblique incidence.
We have observed discrete damage sites generated within the bulk of some materials, such as silicate glass, fluorophosphate glass, and KDP crystals, by 1-ns, 1064-nm laser pulses. The energy fluxes at which bulk damage is initiated are in the range of 2 to 20 J/cm2, much lower than the fluxes required to cause damage by intrinsic processes. Small foreign inclusions (<1 μm diameter) are the cause of these low bulk damage thresholds. The inclusion density varies from 107/cc to less than 10/cc. At threshold the damaged volumes are small (1–5 μm in diameter) and thus, can be observed most easily by their forward-scattered light.
Several photographs are shown to illustrate the onset of bulk laser damage in fluorophosphate glass and KDP crystals.
Diamond turning and precision generation of aspheric metal surfaces has promoted a change in lapping techniques due to the extremely close figure tolerances and surface finishes that have been achieved. In order to polish the unusual aspberic figures, we utilized special tooling, diamonJ abrasive, and silicon oil and techniques which we will describe in detail. Our studies include small flat diamond turned samples of copper, electroplated copper, electroplated silver, electroplated nickel and silver as well as larss aspheres such as an f/0.75, 35 cm diameter copper ellipse. Results from cleaning studies on flat samples using ultrasonics and vapor degreasers will also be summarized. Interferograms of wavefront dis tortion and analysis of focal volume will be included as well as 10.6 -jn reflectivity and a summary of laier carnage experimerts.
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