David Nolte

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A gold ridge microstructure fabricated to a height of lambda/8 on a high-reflectivity substrate behaves as a wave-front-splitting self-referencing interferometer in phase quadrature when illuminated by a Gaussian laser beam and observed in the far field along the optic axis. When immuno-gammaglobulin (IgG) antibodies are selectively immobilized on the gold(More)
Common-path in-line shearing interferometry, combined with pixel-array imaging, provides a surface metrology that achieves 15 pm surface height resolution. An eighth-wave thermal oxide on silicon generates a reference wave locked in the condition of phase quadrature for phase-to-intensity conversion that makes surface height or index variations directly(More)
BACKGROUND We describe a direct-detection immunoassay that uses high-speed optical interferometry on a biological compact disc (BioCD). METHODS We fabricated phase-contrast BioCDs from 100-mm diameter 1.1-mm thick borosilicate glass disks coated with a 10-layer dielectric stack of Ta2O5/SiO2 that serves as a mirror with a center wavelength at 635 nm. The(More)
The bio-optical compact disk (BioCD) is an optical biosensor that performs common-path molecular interferometry of patterned proteins on a disk spinning at high speed. The common-path configuration makes it ultrastable and allows surface height precision below 10 pm. In this paper we show that two complementary interferometric quadrature conditions exist(More)
Common-path differential phase-contrast interferometry measures the spatial gradient of surface dipole density on a bio-optical compact disk (BioCD) and is sensitive to small changes in dipole density following molecular binding of target molecules out of solution. The recognition molecules are antibody IgG proteins that are deposited in periodic patterns(More)
We perform simultaneous interferometric and fluorescent detection of molecular protein layers on a BioCD. The 488 nm excitation wavelength of fluorescein also provides the interferometric detection channel that operates in a common-path in-line configuration in the condition of phase quadrature set by a thermal oxide on silicon. The simultaneous acquisition(More)
Mass transport of analyte to surface-immobilized affinity reagents is the fundamental bottleneck for sensitive detection in solid-support microarrays and biosensors. Analyte depletion in the volume adjacent to the sensor causes deviation from ideal association, significantly slows down reaction kinetics, and causes inhomogeneous binding across the sensor(More)
Spinning-disc interferometry (SDI) is a high-speed laser scanning approach to surface metrology that uses common-path interferometry to measure protein spots on a BioCD disk. The measurement sensitivity depends on the scanning pitch and on the time-base. Based on high-resolution laser scanning images of printed antibody spots, we quantify the protein(More)
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