W.B.Amos, E. Reid and S. Reichelt of the MRC Laboratory of Molecular Biology and the Cambridge Institute for Cancer Research in Cambridge have developed a novel macrolens specifically for 3D microscopy. It is designed to form the basis of a confocal laser scanning microscope, but opens up some interesting possibilities as a camera lens. It is a giant (23 inches long and 3 inches in diameter): it cannot be fitted on to any existing microscope but it can be used with full-frame cameras.  A scan head for confocal and multiphoton use with this lens is under development. The lens is designed for 4x magnification and needs the specimen to be immersed in fluid (anything from water to benzyl benzoate). The novel thing about it is the very high numerical aperture (0.47) for a lens of this magnification, which means it has a depth of field of only about 3 um over a field of 6mm. The chief purpose of this is to facilitate confocal and multiphoton microscopy of objects up to 6 mm wide and 3 mm thick. To do justice to the image, the camera would have to have at least 150 megapixels.

  The first public showing of  this monster lens,  in use with live specimens and a high-resolution camera as part of an exhibit called 'Improving the Magnifying Glass'  will be at the Summer Science Exhibition to commemorate the 350th anniversary of the founding of the Royal Society.  The event  will be held in the South Bank Centre in London 25 June to 4th July 2010 (entry is free).
The lens is very fast, so you can do low power fluorescence and bioluminescence imaging with it and it is hoped that it will be commercially available soon. See http://www2.mrc-lmb.cam.ac.uk/va/newgiantlens/ for details.