Measurement of micro-V-groove dihedral using white light interferometry

This study presents a micro-V-grooves dihedral measurement method using white light interferometry on multiple reflection phenomena. When an optical instrument is used to measure microstructures with steep large gradient faces with high reflection rate, considerable measurement errors caused by multiple scattering or multiple reflecting can be observed. These difficulties have limited the application of white light interferometry in the measurement of microstructures. However, the study has found that the multiple-reflection phenomena can be utilized to measure V-groove dihedral angle. The precision of dihedral measurement is a guarantee of ultra-precise machining of retro-reflection mirrors which requires a non-contact measurement to avoid scratches and surface defects caused by the contact probe. The proposed method is capable of obtaining more accurate surface profile data compared to common white light interferometry. Experimental results verify the method and the consistence between the proposed method and contact mode profilometer.