TABLE OF CONTENTS Light microscopy (Hemsley, 1984; McCrone, 1974) is useful for studying the pigments for color, particle size and distribution, and concentration in films. Although light microscopy is useful for studying polymer surfaces (Hemsley, 1984), its use for the study of surfaces has decreased considerably since the commercial introduction of scanning electron microscopes (SEM). These instruments will resolve detail one-tenth as large (20 nm = 0.02 ?m) as that resolved by the light microscope, and the in-focus depth of field of the SEM is 100-300 times that of the light microscope. A Leica Strata Lab Monocular Microscope in shown in Fig. 2.1.
There are other advantages of the SEM, including ease of sample preparation, elemental analysis by energy-dispersive X-ray analyzer, and, usually, excellent specimen contrast. The light microscope is still important because the cost of an SEM is 10 to 50 times that of an adequate light microscope. In addition, there are many routine surface examinations easily performed by light optics that do not justify use of the SEM. There are at least a few surface characterization problems for which the SEM cannot be used: surfaces of materials unstable under high vacuum or high-energy electron bombardment, samples too bulky for the SEM sample compartment, and samples requiring manipulation on the surface during examination and vertical resolution of detail below 250 ?m. Also, the natural color of the specimen...
