Image Capture in the Projection Shadow X-Ray Microscope

Abstract

In any form of X-Ray microscopy the problem of capturing the image and converting it to a visible form is a central issue because the x-ray flux is invisible. The classical method of recording directly on photographic emulsion suffers from the long delay of film processing and printing but more seriously from inability to provide for interactive specimen and illumination adjustment prior to exposure. The Shadow Projection Method some what reduces these problems because of its fixed focus and its versatile image capture possibilities. This method employs a simple point source of x-rays created at or in the window of a very fine focus X-Ray tube. The specimen is placed beyond the window and thus may be very close to the source while remaining in air or external crude vacuum. Likewise the photographic plate is in air or crude vacuum and thus readily accessible. Since shadow projection can provide most or all of the image magnification, the photographic requirements are greatly reduced. For set-up and less critical work the shadow projection image can be captured on Polaroid instant film, either the plain or the positive negative variety. Ordinary lantern slide emulsion is adequate for even the most critical recording. The fixed focus of the microscope permits one to simply set specimens in place and photograph them, sometimes for hours on end, without refocusing the X-Ray Source.