Leo Barish 1
My career in microscopy began as a child when I received a gift of a rudimentary polarizing Gilbert microscope. I found most fascinating viewing subjects such as pond wa¬ter; thus the microscope awakened an interest in sci¬ence. However, as years went by, my interest in sci¬ence waned and shifted towards music; I wanted to become a professional musician, both classical and popular. I earned a relatively good salary for a young kid by playing clarinet and saxophone in bands. This interest continued through high school, and I had hopes of studying music in college. However, I didn't have enough money and would have to depend on a scholarship to attend such a school which, unfortu¬nately, fell through. Although a major disappoint¬ment, the predicament awakened me to the realiza¬tion that a career in music was not really a practical profession for me; and I decided to pursue my sec¬ondary interest: science.
I could only afford to attend a state college and live at home. Under these circumstances, I stud¬ied textile chemistry and graduated with a B.S. from the only college available to me, New Bedford Tex¬tile Institute that eventually became University of Massachusetts, Dartmouth. One of the formal courses offered there was microscopy. I then attended gradu¬ate school on a fellowship at Lowell Technological Institute that eventually became University of Mas¬sachusetts, Lowell. A course given to me there was in TEM. I received an M.S. in Textile Chemistry from Lowell. Nevertheless, throughout my college educa¬tion I played in bands which was very helpful to supplement my meager income.
Upon graduation from Lowell, my friendly draft board finally caught up with me, and I was in¬ducted into the U.S. Army Chemical Corps. Luckily, I was not shipped to Korea but actually enjoyed my assignment in England where I lived in Oxford.
Upon my discharge, I accepted a position as a Research Associate with Fabric Research Labora¬tories, later to become Albany International Research Co. I was involved in many projects, one of which was the study of the morphology of polymers and fibers which required quite a little work with PLM (measurement of birefringence, growing spherulites, hot stage work, etc.). This subject was taught to me by Freddy Khoury and I became proficient at it. Al¬though I was not the principle microscopist of the lab, I took many photomicrographs, not only for my projects, but some for my colleagues as well.
John Facq was the principle microscopist at the lab and he was superb. His specialty was metal shadowing for light microscopy to exhibit surfaces. Although he did not teach this procedure to me di¬rectly, I was well aware and appreciated the metal shadowing technique as applied to light microscopy since I had learned an analogous method in the TEM course that I took in graduate school.
Shortly after John left the lab, I was called into the director's office. He told me of his decision to assign me as a dedicated microscopist to the lab. At the time I was not at all pleased with this assign¬ment since I felt that I would be "pigeon-holed" into a narrow restricted field, acting merely as service to the lab and thus would be precluded from challeng¬ing innovative work. How wrong I was! Working in this position I quickly realized that I was really not that good a microscopist; therefore, to improve my¬self I read extensively on this subject, practically memorizing Shillaber's Photomicography. In addi¬tion, I practiced and experimented diligently on ap¬plying metal shadowing techniques to light micros¬copy and, in doing so, innovated valuable variations. This elegant method was most useful for displaying surfaces, and I still find it surprising that it was not as popular in the field as it should have been.
Although the results of metal shadowing were generally very effective, it did suffer from a few prob¬lems: productivity was low, the depth of field was shallow, and it did take a great deal of skill to do it well. The advent of the scanning electron microscope corrected the above problems and eventually made the metal shadowing technique rather obsolescent. For several years I tried to convince management to purchase an SEM until we finally got one. Although relatively inexpensive, our SEM was one of the few available at that time that worked well at low accel¬erating voltages and so was especially valuable for low atomic number, low density subjects, such as tex¬tiles, which also had a high tendency to charge.
Although my encounter with SEM has been generally satisfactory, I found shortcomings present that in some ways SEM was inferior to the metal shad¬owing methods applied to light microscopy. Through the years many methods were produced to correct these deficiencies, and I have published or made pre¬sentations on most of these.
The background of some subjects was often obtrusive with SEM which led me to develop "Black Hole" techniques which largely eliminated the prob¬lem. Another obstacle with SEM was that the topo¬graphical contrast was low in many subjects, certainly inferior to that obtainable with metal shadowing tech¬niques. By augmenting the backscatter mode, I could largely match the contrast of SEM to that of metal shadowing.
When imaging textiles with SEM, several problems can be encountered, principally charging and bright edge effects. The problems were analyzed and were largely corrected by the use of a low accel¬erating voltage which was not as popular years ago as it is today. Another problem with SEM noted was with the use of Polaroid type 55 P/N film. When the film was developed for the time recommended, in¬version occurred on the negative at low exposure lev¬els: A negative image actually became positive. By merely increasing the developing time, satisfactorynegatives resulted. Mounting some specimens on studs for SEM can often be difficult; methods em¬ploying the common glue gun were developed and found to be very convenient.
It is often advantageous to display micro¬graphs in color. Since images in the SEM are basi¬cally in black and white, it is sometimes beneficial to colorize them. Today this is commonly done with Photoshop or similar software. Years ago I devel¬oped a method to colorize SEM's using photographic methods employing filters and double exposing.
A problem encountered with SEM is that the minimum standard magnification is often too high. To further lower magnification, I found it sometimes necessary to revert to metal shadowing techniques or sputter coated surfaces with tent lighting. Several methods were developed to lower the minimum mag¬nification with the SEM. These included fabricating photomontages, extending the normal working dis¬tance, or adapting the ECP (Electron Channeling Pat¬tern) mode for imaging. Advantages of the latter method is that an almost unlimited depth of field is created with a magnification of less than 1X.
In addition to overcoming problems with the SEM, I have applied this instrument to study the struc¬ture of natural fibers including medulated wool, coir (coconut) ) fiber, and hog bristles. The degradation of polypropylene fibers by sunlight was reported in a series of papers. Even the study of the intricate struc¬ture of a butterfly wing was astounding.
I have also published on the applications of light microscopy. Among these are: a study of fail¬ure in tire cord; the development of a stereo-macro¬scopic technique to study coatings on cotton fabrics; a study of chromogenic film for microscopy; and the application of sputtercoating and tent lighting. In ad¬dition, smoke and soot were found to be useful for surface enhancement in light microscopy; and by us¬ing the Bertrand Lens, the minimum magnification of a light microscope can be lowered considerably with an almost limitless depth of field.
FOOTNOTES
1 Albany International Research Co, 777 West
Street, P.O. Box 9114, Mansfield, MA 02048-9114