Improvement on theoretical model for thin-wire and slot measurement by optical diffraction

摘要

The customary model, that is, b sinφ= mλ, for the measurement of the sizes of slots and thin wires by optical diffraction has been used widely for a long time. In this design note, the model is analysed theoretically and experimentally andimproved to the new model, b tanφ=mλ. Two calibrating slots and thin wires (thin cylinders) are measured by means of optical diffraction. The results show that the new model b tanφ= mλ is more suitable for describing optical diffraction phenomena andmore accurate for measuring a thin wire's diameter.