A High Resolution (<1 micron) Computer Controlled Imaging System.

One difficulty in the routine analysis of fine root diameter response to environmental stimuli is the lack of scanners with resolutions above 189 p mm-1 (4800 dpi).  A 10% change in diameter of a 0.1 mm diameter root is 0.01 mm or 2 pixels at 189 p mm-1.  Because of innate variability, images need to have a resolution that has a 4 pixel shift when a 10% change occurs (i.e. 378 p mm-1 or better).  Some pasture grasses have fine roots in the 30 micron diameter range, requiring resolutions of 1324 p mm-1 or a relative pixel size of 0.8 micron.  We have achieved a resolution of 1600 p mm-1 by coupling a computer controlled stepper motor X-Y-Z system to a Zeiss dissecting microscope and a 14 Mp digital camera.  The system can be programmed to do image slicing, thus providing high resolution images of three-dimensional objects without depth of field artifacts.