Correlation-coefficient based auto-focusing algorithm for focus detection in shape measurement using two-source digital holographic interferometry

Release Time:2025-04-30  Hits:

• Date:2025-04-30
• Title of Paper:Correlation-coefficient based auto-focusing algorithm for focus detection in shape measurement using two-source digital holographic interferometry
• Journal:Measurement Science and Technology（中科院 3区）
• Summary:In　this　study,　a　simple　auto-focusing　algorithm　to　determine　the　focus　plane　in　shape　measurement　using　two-source　digital　holographic　interferometry　is　presented.　The　wave　fields　corresponding　to　two　illumination　angles　are　reconstructed,　and　the　correlation　coefficient　between　two　wave　fields　is　calculated.　This　parameter　is　affected　by　the　defocusing　of　the　reconstruction　image.　Larger　distances　between　the　reconstruction　plane　and　focus　plane　lead　to　smaller　correlation　coefficient.　Because　this　relationship　is　independent　of　the　strength　of　the　feature　patterns　of　a　specimen,　the　focus　plane　can　be　automatically　determined　as　the　location　of　the　maximum　correlation　coefficient　without　any　artificial　determination.　Finally,　the　shape　can　be　measured　using　two　reconstructed　wave　fields　of　different　illumination　angle.　Experiments　have　been　conducted　to　demonstrate　the　feasibility　of　the　proposed　algorithm.
• Co-author:Dong Jun；Jia Shuhai ;Jiang Chao
• Volume:29(8)
• Translation or Not:No
• Date of Publication:2018-07-12