NOTE: While performing these tests, we inadvertently multiplied the y-axis by 0.2 therefore reducing the FOG signal by a factor of 5. We repeated the 'bottom' test again and confirmed that a temperature change of 1/5 the previous value (that is, 0.05°C) causes an excursion in the FOG output of equal magnitude to Martin's latest published results. Time permitting, we will update the graphs on this page. Meanwhile, you can multiply the y axis values of the graphs below by 5 for the correct values.
We constructed a test bed to measure the temperature sensitivity of the FOGs currently being used in the Tajmar experiment. We placed the FOG on an aluminum plate whose temperature was regulated by two peltier thermoelectric devices. The FOG was held onto the plate by rubber bands so that the orientation of the FOG can be quickly changed to test temperature sensitivity of all its faces. When the FOG was mounted so that the sides were in contact with the temperature controlled plate, the entire assembly was turned on its side such that the FOG's sensitive axis was in the same orientation (i.e. normal to the surface of the desk). The temperature of the mounting plate was measure with a sensor embedded in it's upper surface and controlled via computer. We did not have a temperature sensor thin enough to obtain the true temperature of the FOG face in contact with the plate. We placed a thermistor on one of the exposed sides as near as possible to the side in contact with the plate.
Below
are photographs of the equipment used in the test and the FOG assembly.
The label on each graph refers to the side of the FOG that is in contact with the temperature controlled plate. All graphs have the same scale for the FOG output – each division is 0.0005 deg/sec.
Legend:
White/Black: FOG output
Green: temperature as near as possible to face touching plate
Red: temperature of plate
Blue: temperature set point
The bottom showed the most temperature sensitivity. A change of 1°C in the mounting plate (which corresponds to a 0.25°C change in the bottom plate of the FOG) caused an excursion of about 0.001 deg/sec in the FOG output. The published results in Martin's latest paper show a maximum signal of 0.0014 deg/sec.
NOTE: New tests with proper scaling factors have shown that a 0.05°C change in the temperature of the FOG causes an excursion in the output of equal magnitude to Martin's latest published results.
All other faces were less sensitive to the same temperature change. The top, for example, showed only a slight response to a 5°C change in the mounting plate temperature. A 10°C change did produce an excursion in the FOG output of about the same magnitude as a 1°C change on the bottom. The other sides reacted much the same way.
