Research On The Measurement Of The Residual Acceleration Of The Drop Capsule With The Method Of Laser Interference

It is generally accepted that matter has different rules of movement in microgravity state from that in normal gravity state,which brings new study fields to the development of such natural subjects as fundamental physics, fluid physics, materials science and biotechnology. In the experiments which are performed on the ground, the microgravity condition can be obtained in the drop tower, so it is very important to measure the residual acceleration of the drop capsule. In Germany, Japan and other countries, the residual acceleration of the drop capsule is measured with a precise accelerometer. But as the sale of the accelerometer to our country is under an embargo, no appropriate method which can be used to measure the residual acceleration of the drop capsule in the Drop Tower in the National Microgravity Laboratory has been proposed. In this paper, a method of measuring the residual acceleration of the drop capsule by using laser interference is brought forward. The basic principle can be described as following: a reference object falling in the drop capsule can fall more freely than the drop capsule because the outer air drag acts on the latter, so there is a difference of acceleration between the reference object and the drop capsule. The difference of the acceleration can be obtained according to the relative displacement which can be measured by laser interference. This method is discussed in details, and it is tested by a simulation experiment.