An Automatic Image Acquisition and Analysis System for a Scanning Electron Microscope

A restriction on the wider use of image processing and analysis methods in many disciplines has been the need to analyse large numbers of images to provide the necessary statistical basis for comparison between one specimen and another. Many image processing and ana-lysis routines such as image restoration, orientation analysis, objective segmentation for porosity analysis, and granulometric greyscale morphological methods are well established. Many are readily adapted to batch processing without the need for operator intervention, but the acquisition of the raw images themselves becomes a constraint. An image processing facility has been adapted to control automatically a Hitachi S800 scanning electron microscope and to provide basic image capture facilities. This in turn exchanges data with a separate dedicated image analysis facility running on a personal computer. Basic control of brightness, magnification, focusing and stage position are programmed to include various image capture sequences including regular grid arrays, random acquisition, and acquisition at pre-selected points. The magnification can be varied between one image and another. Up to 400 separate images have been captured in a single operation and this has required the development of a database system and file management system within the image processing facility to record key parametric information such as magnification and specimen co-ordinates. During image capture of one image, the dedicated image analysis facility analyses the previous image in the sequence. Full information is stored about each image and the specimen position can be readily recovered for further image capture under different operating conditions if required.