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Actinic patterned mask inspection (APMI) is the last major part of the infrastructure required for EUV lithography to be developed. A coherent imaging approach is proposed as a plausible solution requiring incremental improvements to available components. Diffractive optics direct a mW 13.5nm coherent beam to the mask and to interfere at the imaging detector. A motion system translates the mask between exposures. A non-iterative algorithm generates a complex reflectivity (mask image) estimate from each interferogram, in real time with GPU hardware. Realistic simulation results and requirements for the system components are presented. Except for the FEL that is likely required, many elements of the system are simpler and likely less costly than an incoherent imager. The system can be configured to image the mask through a pellicle. Of note, focus tolerance is loose as the focal distance is a software parameter.

Surface-assisted laser desorption/ionization (SALDI) substrates have been fabricated using nanospiked polyurethane (PU) substrates that are replicated by a low-cost soft nanolithography method from silicon nanospike structures formed with femtosecond laser irradiations. The strongest mass spectrometry (MS) signal of Angiotensin II was obtained on 45-nm Au-coated nanospiked PU substrates. The effective ionization appears to be due to surface plasmon excitation. Such low-cost and identical SALDI substrates can be used for MS analysis of various molecules with high reproducibility. Copyright © 2011 John Wiley & Sons, Ltd.

Nearly index-matched optical elements are described that have application to aspherical, diffractive, and hybrid refractive -diffractive elements. Owing to the small difference in index, tolerances on the interfacial surface profile are much looser than for conventional aspherical and diffractive elements. A condition on both the index and the dispersion is described that results in an achromatic phase, thereby allowing for diffractive elements with high efficiency over broad spectral bands. Properties of the elements are described and compared with those of conventional diffractive elements. Analytical results and experimental measurements with an inexpensive element with 40 waves of asphericity are presented.

A new gamma camera with intrinsically high-resolution is described. A scintillating crystal is imaged onto a photon-counting 2D imaging detector. Most of the light is directed to PMTs for energy determination in this patented detector. Detection time and position can be recorded. Time resolution is as fine as the scintillation pulse allows. Sub-millimeter resolution has been achieved and 2048 linear pixels are possible. We are fabricating a transportable detector with 25 cm sensitive diameter and 1024x1024 pixels. Results taken with a prototype detector are presented.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A novel design for a zero-order achromatic diffractive optical element is presented. Applications of the optical element are discussed. Tolerances on the material properties and fabrication considerations are presented. The predicted performance characteristics, including optical efficiency and effective bandwidth, are presented.

We present the first experimental results of recovery of the 2-D spatial coherence modulus and phase using fourth order correlation interferometry (FOCI). The technique, a generalization of intensity interferometry and laser speckle correlography, measures the correlation (I(x)A*(x+A)A(x+A+c)), where 1(x) and A*(x+E)A(x+A+e) are measured with separate, unconnected apertures. The result of the measurement is t*(A)i(+c), a cross-product of the spatial coherence factor that is analogous to the Knox-Thompson cross-spectrum in astronomical speckle imaging. The technique has applicability when the coherence function must be measured over distances A which are larger than the diameter D >> XE of the largest diffraction limited optic or amplitude interferometer and the field is a circular complex Gaussian random variable. An experiment is described which makes the correlation measurement on a series of laser speckle patterns. 1(x) and A*(x+A)A(x+A+e) are obtained from the focal spots of an array of lenslets. The measured coherence function is shown to agree with the expected value. The intensity image, given by the Fourier transform of the coherence function, is calculated and gives good agreement with the experiment target. The usefulness of the technique is discussed.

We describe an instantaneous modal wave-front sensor. The sensor uses a Shack-Hartmann lenslet array to encode the wave-front distortion. A novel parallel electro-optic processor continuously converts the spot pattern to wave-front modes, e.g. Zernike polynomials, without a separate reconstructor. Using readily available components, the sensor can achieve MHz bandwidths for twenty modes. The bandwidth, sensitivity, and number of bits can vary for each mode to match the sensor to the disturbance in an optimal fashion. The proposed sensor has immediate application to beam control and turbulence sensing applications that require wide bandwidths. The measured wave-front modes can also be those of an adaptive optics system, directly providing control signals for the actuators of a deformable mirror. A similar electronic reconstructor mode is also described.