APPLICATIONS OF TECHNOLOGY:
- EUV photolithography mask inspection
- Imaging in astronomy, biology, and other disciplines
- Soft x-ray imaging
- Simplifies and increases data collection in microscopes by 2x or more
- Simultaneous multiple-image capture
- Minimizes non-uniformities to improve data quality
- Easily integrated with conventional microscopes
Berkeley Lab scientists Kenneth A. Goldberg and Iacopo Mochi have developed a holographic technology to create multiple images simultaneously from a single lens with highly flexible, distinct optical properties for each image.
For microscopy, where many applications require 3-D imaging modes that collect a series of images moving through focus, the original lens can be modified or replaced to include a holographic multiple lens (HML). Each element of the HML can be designed with a specific amount of defocus and tilt to simultaneously project a number ofdistinct images onto a CCD camera in a tiled array. Acquiring multiple images in a single exposure minimizes random variations from illumination and stage motion that can otherwise reduce data quality.
The technology can be adapted to photomask microscopes designed for extreme ultraviolet (EUV) lithography (13-nm wavelength) applications or other soft x-ray imaging-microscopy applications where Fresnel zoneplates are commonly used. Modification of the simple Fresnel zoneplate lens to include the HML pattern could improve through-focus data collection. Similar advantages are seen when a hybrid holographic lens (HHL) simultaneously captures both brightfield (BF) and darkfield (DF) images—an advance suitable for the challenging task of detecting tiny amplitude and phase defects on EUV masks. The hybrid zoneplate lens accomplishes the effect with a dual-purpose holographic element that spatially separates BF and DF images that are projected onto one or two detectors, imaging the same region of the sample in two different modes.
This holographic lens concept is also relevant for numerous disciplines that capture imaging data. The simultaneous recording of BF and DF images could be very useful for enhancing detection sensitivity or data analysis of biological samples, for example. The HML, with its multi-focus objective, is particularly suited for imaging fast moving objects or systems where mechanical stability cannot be guaranteed between successive exposures.
Holographic lenses are easily mass-produced and, for EUV and other special applications, are less expensive than traditional lenses of similar quality. Customized HHLs could also be used in combination with conventional microscopes to provide additional capabilities, further expanding the reach of this promising technology.
DEVELOPMENT STAGE: Bench scale prototype. The underlying principles have been bench tested with two implementations.
STATUS: Patent pending. Available for licensing or collaborative research.
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REFERENCE NUMBER: WIB-2635