FIGURE 1.

Sectional view of the temperature-controlled specimen holder. Inner walls and the bottom are constructed of steel plates, which contact with Peltier devices of temperature range 0–70°C. Temperatures immediately above and below the sample (coverslip observation chamber) are monitored by two thermocouples. Small pieces of thermochromic liquid-crystal film are attached to the top surface of the chamber to read the sample temperature to within ±1°C. The example shown is for the measurement at 4°C, where pieces 3–5, respectively, respond to 3–5°C, and the sample area shown in brown is observed. In some measurements, an identical set of thermochromic film was also attached to the bottom surface; the readings of the top and bottom agreed within 1°C.