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Title: DIFFERENTIAL CONTRAST IMAGING OF SE-SIGNALS IN CRYO-FESEM

Author
item PETERS, K R - UNIV. OF CONNECTICUT
item WERGIN, WILLIAM

Submitted to: Scanning
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Information needed to solve many agricultural problems must be gained observing samples of crops and animals, as well as their pathogens and parasites, in sophisticated microscopes called low temperature scanning electron microscopes. To observe agricultural samples in these instruments, they must be pretreated using elaborate preparation techniques ssuch as very rapid freezing (microseconds) and coating with thin films of metals (1/2,000,000 of an inch in thickness). In spite of these techniques, which must be routinely used by all investigators, a problem is that details in the final picture are often lost or reduced due to a phenomenon that arises in the microscope and is known as "charging related contrast deficiencies." We have written a computer program that was used to show considerable improvement in the pictures that are routinely obtained with a low temperature scanning electron microscope. This program mwill be used by scientists to identify structural features of agricultural organisms that were previously indistinct or not visible with this instrument.

Technical Abstract: The modern cryo-FESEM instruments can provide for LTSEM many benefits in imaging fully hydrated frozen surfaces, but ease of application, as well as maximum resolution, is limited by unavoidable charging related contrast deficiencies. Conventionally, these problems are reduced but not overcome through application of heavy metal coating and conventional image processing. We analyzed images obtained by LTSEM with a mathematical signal processing technology that utilizes the hysteresis properties of the data for quantitative contrast segmentation. This contrast analysis resulted in the characterization of several new properties of cryo-FESEM images that have the potential to vastly improve, if not optimize LTSEM, with these instruments by providing improved imaging capabilities at maximum resolution levels and rendering control over the required etching process for the exposure of the surface's ultrastructure.