Indirect method for the measurement of bubble collapse field in negative temperature range

The bubble collapse field Ho of 2-6μm LPE garnet films was measured by an indirect method in an instrument which provide a sample chamber with negative temperature controller for temperature as low as to -50°C. Because of indirect method of measurement that did not require the use of the eye to observe the collapse of bubble, not only the subjective error of measurement was avoided, but also the focusing of sample was unnecessary Therefore the distance of the sample and objective can be increased to benefit the design of temperature chamber. The temperature is controlled by the gas flow from liquid nitrogen. During the measuring time the freeze phenomena was not serious to effect the light signal, so the negative temperature measurement of bubble collapse field can be easily carried out. For comparison, the Ho(T) curves for temperature region -50-200°C are given.