Precision measurement on the diameter of thin thread by using the diffraction method

An analysis was made on the important factors that affect the accuracy in measuring the diameter of thin thread through using the laser diffraction theory, and on this basis, an accurate processing and recognizing technique was developed for the weak diffraction fringes to effectively improve the measurement accuracy. The experimental results show that the repetition accuracy of ±0.1 μm can be realized within the range of 10-50 μm with the discussed technique, and the resolution is better than 0.01μm.