Reflection-transmission phase shift: interferometer and viewing optics.

The interferometer and viewing optics that are the main optical components of an automated surface mapping system used to characterize the surface topography and the wall thickness uniformity of opaque and transparent spherical shells are described. To characterize surface finish or wall thickness of spherical shells with an accuracy of 10 nm and a resolution of 1 microm, the differential phase shift between two beams of orthogonal polarizations is measured before and after the probe beam has interacted with the test object.

X-ray measurement of laser fusion targets using least squares fitting.

This paper presents an x-ray technique for measurement of opaque hollow microspheres used as laser fusion targets. We describe a nondestructive method for holding microspheres that enables microsphere rotation between x-ray exposures. We record film images of the microspheres using contact microradiography. We use computer image analysis for measurement of the microsphere characteristics, which involves mathematically modeling processes that relate the microsphere characteristics to film density and then applying a least squares fit of the model to the image data. We compared this measurement with the optical interferometric measurement for several glass microspheres and found measurement differences <0.3 microm for wall thickness and 0.1 microm for nonconcentricity.

Simple manipulator for rotating spheres.

We describe a simple device for rapidly rotating a small sphere to any orientation for inspection of the surface. The ball is held between two small, flat surfaces and rolls as the surfaces are moved differentially parallel to one another.

Interferometric measurement of laser fusion targets.

We describe techniques for the quantitative interferometric characterization of wall thickness variations of hollow glass microspheres. By using a combination of techniques, one can rapidly form a picture of the total configuration for most defect combinations. These techniques require only very simple calculations and do not involve detailed ray tracing through the sphere. We also show how ray tracing calculation can be done very simply for careful analysis of the interference phenomenon in a perfect sphere. These calculations show that if both a large illumination angle and a large aperture objective are used, the nonparallel illumination causes degradation of both the spatial and the phase resolution of the interferometer. These problems can be overcome by properly aperturing the illumination.

Composite x-ray pinholes for time-resolved microphotography of laser compressed targets.

Composite x-ray pinholes having dichroic properties are presented. These pinholes permit both x-ray imaging and visible alignment with micron accuracy by presenting different apparent apertures in these widely disparate regions of the spectrum. Their use is mandatory in certain applications in which the x-ray detection consists of a limited number of resolvable elements whose use one wishes to maximize. Mating the pinhole camera with an x-ray streaking camera is described, along with experiments which spatially and temporally resolve the implosion of laser irradiated targets.