Nanowatt Optical Pressure Measurement Experiment Based On Precision Torsion Balance Technology

Light pressure,as a tiny quantized force value,is of great research value.The measurement of light pressure was first proposed by Maxwell.However,due to the heat accumulation effect generated when light incident on the surface of an object,the thermal motion of surrounding gas molecules will be intensified,resulting in Crookes radiation effect on the surface of an object in addition to light pressure.Therefore,on the basis of the extremely weak light pressure itself,combined with the radiation effect,it is extremely difficult to measure the light pressure.Although today,there are many measurement methods of light pressure,such as torsion balance method,piezoelectric crystal method,plate capacitor method,thin film method,liquid method and so on,through the above method can be measured than the Lebedev measurement value of light pressure,but for small light pressure such as the small light pressure under the power of Nava light pressure by the above method is basically difficult to measure.Therefore,in order to obtain the optical pressure of Nava in the experiment,this paper innovatively constructed a new torsional balance system,which solved the problem of improving the sensitivity of the torsional balance from the selection of twisted wire to the optimization of the experimental environment,so that the produced torsional balance is high Q and high sensitivity,so that the low-light level force of Nava can be measured.This paper mainly uses tungsten wire and quartz wire as torsion scales to make precision torsion scales with high Q and high sensitivity.Based on the technology of precision torsion scales,this paper successfully measured the optical pressure of the laser beam with linear frequency0f(28)4m HZ and optical power modulation amplitude of about 712 n W as τ(28)1.21×10-16 Nm.The effectiveness and accuracy of the experiment were determined by comparing the calculated theoretical optical pressure value τ(28)1.25×10-16 Nm with the experimental data.In the experiment,tungsten wire with a diameter of 8 microns and quartz with a diameter of about 5microns were used as torsion wires to make high-Q and high-sensitivity precision torsion scales to measure the light pressure of Nava.Tungsten wire can be purchased through the market and micron quartz wire is very rare,so to be able to produce micron quartz wire torsion to meet the requirements of the experiment becomes the primary breakthrough point in this paper.In this paper,the whole torsion balance system is innovated and improved,and the structure of torsion balance is changed to create a highly symmetrical torsion balance structure,and the sensitivity of torsion balance is improved by making torsion wire of different materials that meet the diameter requirements of experimental torsion wire.The influence caused by simple pendulum movement is suppressed by adding magnetic damping structure.Since the experimental environment will bring certain errors to the Angle measurement of torsion balance,Such as temperature,wind,etc.,but the most important is the error brought by the thermal noise interference in the environment to the experimental measurement,so this paper specifically analyzes the thermal noise of the torsion balance system,the nonlinear effect of the torsion wire and the influence in the process of processing and construction,and so on to obtain the error impact of the experimental data to achieve the effectiveness and accuracy of the data.