David F. J. Tees, Ph.D.
Assistant Professor
Ohio University
Most of the experiments performed in Chapters 2 and 3 were carried out in the Rheoscope. In Fig. A2.1, the device is shown in operation mounted on the inverted microscope with its associated electronics. Figure A2.2 shows a close up with the cone and plate opened for filling.
FIGURE A2.1 Overall view of the Rheoscope, the inverted microscope and its associated electronics. The Rheoscope (A) (shown closed) [speed control box (B)] replaces the stage of a Leitz Diavert inverted microscope (C) [power supply (D)] which rests on a Styrofoam pad (E) for vibration isolation. Doublets in the plane of no translation of the Rheoscope were recorded using a Sony CCD camera with high speed shutter (F) [power supply (G)]. Video output was combined with a time signal generated by a digital timer (H), recorded on a Panasonic AG-7300 video cassette recorder (I) [remote controller (J)], and displayed on a video screen (K). A doublet is seen at the upper right of the screen with the time display in the lower left corner. The axes and crosshair were added by a video position analyzer (L), which was used for measuring particle size and doublet orientation. Once a doublet had been found and a sample of its rotation videotaped at high magnification, the size and orientation were entered into the HP 9000 model 216 computer (M) together with the temperature measured using the digital thermometer (N) (the temperature sensor was taped to the Rheoscope housing--see Fig. A2.2). The computer determines the Rheoscope setting required to produce the chose maximum normal force. The Rheoscope controller dial (O) is set to this value.
FIGURE A2.2 Detailed view with the Rheoscope, mounted on the Leitz Diavert inverted microscope. The device has been opened to reveal the transparent cone in its cone holder (A) and the plate (B) with the plate holder (C). The cone holder is held and driven by pins (not visible) in the upper drive housing (D). The plate holder has a magnetic ring on its underside which couples it to the lower drive housing (E). Both cone and plate drives are geared to the same electric motor (just visible, F) which allows them to rotate at the same speed in opposite directions. The radial position of the cone and plate assembly is adjusted using a micrometer (G) and the entire Rheoscope can be adjusted vertically using the focusing knob (H). The temperature is measured by the temperature sensor taped to the lower housing (I).