Specialized Diffractive Optics
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Specialized diffractive optical elements are being developed to improve contrast and resolution for imaging studies in the soft x-ray region. The techniques are developed at the spatially coherent soft x-ray test station, the full-field soft x-ray microscope XM-1, and the CXRO nanofabrication facility and can be extended for use with compact sources. Both lens based imaging methods utilizing unconventional zone plates and lens-less imaging methods employing improved reference objects are being pursued.
For high resolution lens based imaging, three classes of zone plates are being studied:
Each of the optics, serving as the single objective lens in the imaging system, performs both the imaging and an additional image processing capability. For example, the spiral zone plates provide a method to image the object's local gradient of refractive index, being sensitive to changes in both phase and amplitude in a specimen. The Zernike zone plates allow soft x-ray Zernike phase contrast imaging without the use of an additional phase ring, and the wavefront coded zone plates allow depth of field extensions for high resolution three dimensional imaging. In addition, resolution and signal to noise improvements for lens-less imaging methods, such as holography, are being made through the use of the uniformly redundant array.
For more information, please see the publications.
