Classical interference microscopy

Classical interference microscopy utilizes two separate light beams with greater lateral separation than that used in differential interference microscopy (DIC). This can be as much as 6cm (as in the double-optics Mach-Zehnder system of Leitz).

The main advantage offered by the instrument was the possibility of measuring the projected dry mass of living cells, which was best exploited by Andrew Huxley in his studies of striated muscle cell structure and function. Huxley, A. F. & Niedergerke, R. Nature 173, 971−973 (1954).

In many variants of the interference microscope the images produced of the object may necessarily be duplicated, separated either laterally within the visual field or at different focal planes. Interference microscopy became relatively popular in the 1940-1970 decades but fell into disuse because of the complexity of the instrument and difficulties in both its use and in the interpretation of image data. In recent years the classical interference microscope has been "rediscovered" because its main üriginal disadvantage (difficult interpretation of translated interference bands or complex coloured images) can now be easily surmounted by means of digital camera image recording, followed by powerful computer algorithms which rapidly deliver the processed data as false-colour images of projected dry mass.

Instrumentation History

• Smith system (C. Baker, London, England)
• Dyson (Cooke Troughton & Simms, York, England)
• Jamin-Lebedeff (E. Leitz, Wetzlar, & Zeiss, Germany)
• Mach-Zehnder (E. Leitz, Wetzlar, Germany)