The design of a wavefront sensor may be determined by the lenslet array and camera selection. There are numerous different applications for these sensors, requiring widely differing dynamic range and accuracy. Performance metrics are needed to evaluate candidate designs and to compare results. We have developed a standard methodology for measuring the repeatability, accuracy and dynamic range of different wavefront sensor designs, and have experimentally applied these metrics to a number of different sensors

The surface topography of thin, transparent materials is of interest in many areas. Some examples include glass substrates for computer hard disks, photomasks in the semiconductor industry, flat panel displays, and x-ray telescope optics. Some of these applications require individual foils to be manufactured with figure errors that are a small fraction of a micron over 10-to 200-mm lengths. Accurate surface metrology is essential to confirm the efficacy of manufacturing and substrate flattening processes. Assembly of these floppy optics is also facilitated by such a metrology tool. We report on the design and performance of a novel deep-ultraviolet (deep-UV) Shack-Hartmann surface metrology tool developed for this purpose. The use of deep-UV wavelengths is particularly advantageous for studying transparent substrates such as glass, which are virtually opaque to wavelengths below 260 nm. The system has a 143ϫ143-mm 2 field of view at the object plane. Performance specifications include 350-rad angular dynamic range and 0.5-rad angular sensitivity. Surface maps over a 100 mm diam are accurate to Ͻ17-nm rms and repeatable to 5 nm rms.

We have developed a two-dimensional Shack-Hartman wavefront sensor that uses binary optic lenslet arrays to directly measure the wavefront slope (phase gradient) and amplitude of the laser beam. This sensor uses an array of lenslets that dissects the beam into a number ofsamples. The focal spot location of each of these lenslets (measured by a CCD camera) is related to the incoming wavefront slope over the lenslet. By integrating these measurements over the laser aperture, the wavefront or phase distribution can be determined. Since the power focused by each lenslet is also easily determined, this allows a complete measurement of the intensity and phase distribution of the laser beam. firthermore, all the information is obtained in a single measurement. Knowing the complete scalar field of the beam allows the detailed prediction of the actual beam's characteristics along its propagation path. In particular, the space-beamwidth product, @, can be obtained in a single measurement. The intensity and phase information can be used in concert with information about other elements in the optical tiain to predict the beam size, shape, phase and other characteristics anywhere in the optical train.We present preliminary measurements of an Ar+ laser beam and associated @ calculations.

Our experimental results are consistent with the hypothesis that reflected NIR light captured by the aberrometer originates from scattering sources located posterior to the entrance apertures of cone photoreceptors, near the retinal pigment epithelium. The larger myopic bias for brown eyes suggests that a greater fraction of NIR light is reflected from choroidal melanin in brown eyes compared with blue eyes.

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