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Proceedings Paper

Soft x-ray contact microscopy using laser-generated plasma sources
Author(s): Julian H. Fletcher; Robin A. Cotton; Colin E. Webb
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Paper Abstract

Of the three main approaches to soft x-ray microscopy currently being investigated (contact, scanning, and direct imaging), we believe that, at present, contact microscopy provides the only solution to the problems of user access to working x-ray microscope systems and radiation damage to biological specimens. A small, transportable, discharge pumped, UV pre- ionized KrF laser system has been developed for the exclusive use of contact microscopy. By employing an injection seeded unstable confocal resonator, a beam of 2.5 times the diffraction limited divergence and energy of the order of magnitude 2 J is generated. By focusing this beam onto the surface of a suitable target material with an intensity of the order of magnitude 1012 W/cm2, a plasma is created which emits largely in the water window region of the spectrum with an efficiency of up to 20%. These x-rays are used to illuminate a biological specimen which is placed in close contact with a photosensitive resist such as polymethyl methacrylate. The specimen may be hydrated and requires no prior preparation such as staining or fixation. A transmission map of the specimen is recorded in the resist within 25 ns, before radiation damage can effect the specimen's structure. After chemical development, during which exposed areas of the resist are preferentially dissolved resulting in a relief map of the x-ray transmission of the specimen, the resist is viewed in an SEM or alternatively an atomic force microscope (AFM). Images of various biological specimens are presented.

Paper Details

Date Published: 13 January 1993
PDF: 12 pages
Proc. SPIE 1741, Soft X-Ray Microscopy, (13 January 1993); doi: 10.1117/12.138728
Show Author Affiliations
Julian H. Fletcher, Univ. of Oxford (United Kingdom)
Robin A. Cotton, Royal Holloway and Bedford New College (United Kingdom)
Colin E. Webb, Univ. of Oxford (United Kingdom)

Published in SPIE Proceedings Vol. 1741:
Soft X-Ray Microscopy
Chris J. Jacobsen; James E. Trebes, Editor(s)

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