Benchtop Diffractometer
for Evaluation of Electron Micrographs

















  • Compact ergonomic hi-tech design with small footprint.

  • Allows high resolution video capture of both diffraction and real-space images.

  • Laser safe

  • Diffractometer constant variable over a 6-fold range

  • Real time search mode with instant switching between real and reciprocal space.

  • Does not require a darkened room.

  • Laser-generated cross-hair for marking location of selected regions on the negative.

  • Images can be viewed on monitor by groups, e.g. for teaching.


This instrument was developed in the MRC Laboratory of Molecular Biology, Cambridge, where the diffraction analysis of electron micrographs was first introduced in the 60s by Klug and De Rosier.

The design, which has been tested by extensive use within the MRC, eliminates the difficulty and eye-strain of earlier diffractometers. Visual observation of the laser light is totally eliminated. Instead, a novel optical design allows the use of two high-resolution video cameras to capture the diffraction pattern and the real-space image simultaneously. It is possible to scan over a negative rapidly, using the real-time video image, and switch instantaneously to the corresponding diffraction pattern.
The magnification of both the real and the reciprocal space images can be varied independently.

To facilitate the surveying of large numbers of negatives, particular attention has been paid to the stage of the diffractometer, which allows translation and rotation of the image around a fixed centre. The holder makes contact only with the edges of the negative and the masking baffles do not make contact with the negative. By connecting the output of the instrument to a computer equipped with a monochrome video frame grabber, both real space and diffraction images can be recorded in digital form. A video cross-hair generator can also be used for measurement with single-pixel precision.
Specifications
Optics The principal optics are aplanatic coated telescope doublets giving diffraction-limited performance throughout the diffractometer field.

Light sources. Microlens diode (637nm) of 8-10 mW , attenuated by a 25 um spatial filter. Incoherent source for real space image broadband, centred at 520nm.

Dynamic range. Laser intensity variable over a 1000-fold range, allowing the examination of negatives of any optical density.

Maximum diameter of viewed area of negative. 29mm

Diffractometer constant. Basic setting: 0.1mm = 104pixels in diffraction image (767 x 575 pixels total size). Variable within the range 0.1mm = 49 pixels to 0.1mm = 316 pixels.





The estimated price of this instrument, if produced commercially, would probably be in the range of 45-55,000 US dollars. If you are interested in purchasing such an instrument, please contact:


W.B.Amos
MRC LMB
Hills Road
Cambridge
CB2 2QH
Phone: 01223-411640
e-mail: ba@mrc-lmb.cam.ac.uk