Simultaneous dual-surface profile determination of transparent objects using orthogonal grating transmissive phase deflectometry

Abstract

The accurate and simultaneous measurement of surface profiles of transparent objects is crucial for evaluating optical performance, ensuring quality control, and maintaining functional integrity. However, existing methods face challenges due to complex setups, reliance on surface reflectivity, the need to maintain the same stress state, or the inability to measure dual surfaces simultaneously. In this study, a novel non-contact optical measurement method using orthogonal grating transmissive phase deflectometry is proposed to determine the profiles of both the upper and lower surfaces of transparent objects. This method establishes a relationship between phase differences and surface profiles by tracking the propagation of light rays, enabling iterative reconstruction of dual-surface profiles with minimal boundary conditions. The technique does not require changing the light source or propagation medium during measurement, thereby significantly reducing operational complexity and cost while mitigating the impact of weak surface reflection and parasitic fringes. Additionally, accuracy is enhanced by adopting an integration path that bypasses the defects. Validation experiments conducted using a meniscus lens demonstrated that the experimental results are consistent with theoretical values. This study provides a cost-effective, high-accuracy, easy-to-operate, and universally applicable solution with potential applications in industrial manufacturing and bioengineering.