Maker's Name: 
Unicam, England
19 × 30 × 26 cm

This device is an X-ray camera that is suited for taking photos of x-ray diffraction patterns and was used in the Chemistry department at UQ. Unlike the X-ray powder camera, however, this device can take images from multiple methods of x-ray photography. Removeable from the main body are two sections - a metal cylinder, and a flat back plate. The cylinder is used for the oscillation method of x-ray photography and the flat screen is used for Laue photographs. The attached microscope tube is used for alignment purposes.

The oscillation method describes a form of x-ray photography where x-rays are shone through a crystal sample in order to produce a diffraction pattern that resembles a set of concentric rings. Then, the crystal is rotated by some angle and the x-rays are shone through again to produce a new set of rings. The user may then observe the change in the pattern and using the image produced find the unit cell length of the crystal used.

Laue photography using the back plate consists of transmission, and back-reflection x-ray photography. Back-reflection involves shining x-rays through a hole in the back plate (and so also a hole in the photo paper) and capturing the image of the reflected x-rays and their diffraction pattern as they undergo Bragg scattering. The Transmission Laue method has the photo paper behind the crystal and the recorded pattern is of x-rays that pass through the crystal. The resulting image is a series of dots where the x-rays strike the paper. This method is useful in determining the perfection of the crystal as each point may become distorted if there are irregularities in the shape of the crystal. The main use of Laue photography is to assess the orientation of the crystal, however, and this is found using special tables that the user may match each x-ray point to.

A similar device was used by Raymond Gosling at Kings College in London to obtain the first clear DNA photgraphs for Maurice Wilkins and Rosalind Franklin. This specific device was built by Unicam. The Unicam Instruments Ltd. Company was founded by S.W.J. Stubbens who was previously a foreman at the Cambridge Instrument Company. In 1968 it merged with W.G. Pye to become Pye Unicam, and in 1988 became defunct. The remainder of the company was merged with Phillips, a company originally based in the Netherlands, but operates around the world.

This item is part of the UQ Physics Museum Crystallography Tour
< Previous Item | Return to Tour Menu | Next Item >