A new miniature hydrostatic pressure chamber for microscopy. Strain-free optical glass windows facilitate phase-contrast and polarized-light microscopy of living cells. Optional fixture permits simultaneous control of pressure and temperature.

This paper describes the development of a miniature, temperature-controlled, stainless steel pressure chamber which uses strain-free optical glass for windows. It is directly adaptable to standard phase-contrast and polarized-light microscopes and requires a minimum amount of equipment to generate and measure pressure. Birefringence retardation (BR) og 0.1 nm up to 3,000 psi, 0.4 nm up to 5,000 psi and 1.0 nm up to 10,000 psi can be detected over a 0.75-mm central field with two strain-free Leitz 20 times UM objectives, one used as a condenser. In phase-contrast studies a Nikon DML 40 times phase objective and Zeiss model IS long working-distance phase condenser were used, with little deterioration of image quality or contrast at pressures as high as 12,000 psi. The actual design process required a synthesis of various criteria which may be categorized under four main areas of consideration: (a) specimen physiology; (b) constraints imposed by available optical equipment and standard microscope systems; (c) mechanical strength and methods for generating pressure; and (d) optical requirements of the chamber windows. Procedures for using the chambers, as well as methods for shifting and controlling the temperature within the chamber, are included.