Profile-based intensity and frequency corrections for single-snapshot spatial frequency domain imaging

Abstract

We have proposed the profile-based intensity and frequency corrections for single-snapshot spatial frequency domain (SFD) imaging to mitigate surface profile effects on the measured intensity and spatial frequency in extracting the optical properties. In the scheme, the spatially modulated frequency of the projected sinusoidal pattern is adaptively adjusted according to the sample surface profile, reducing distortions of the modulation amplitude in the single-snapshot demodulation and errors in the optical property extraction. The profile effects on both the measured intensities of light incident onto and reflected from the sample are then compensated using Minnaert’s correction to obtain the true diffuse reflectance of the sample. We have validated the method by phantom experiments using a highly sensitive SFD imaging system based on the single-pixel photon-counting detection and assessed error reductions in extracting the absorption and reduced scattering coefficients by an average of 40% and 10%, respectively. Further, an in vivo topography experiment of the opisthenar vessels has demonstrated its clinical feasibility.

Generic and Model-Based Calibration Method for Spatial Frequency Domain Imaging with Parameterized Frequency and Intensity Correction

“…In the simplified case of a flat sample, the diffuse reflectance can be corrected by measuring a reference sample with known optical properties at exactly the same position [ 10 ]. For more complex sample surfaces, various profile corrections have been reported based on phase profilometry [ 16 , 17 , 18 , 19 ]. In addition to triangulation-based approaches, which require knowledge of the system parameters, e.g., the relative position between the projector and camera, multi-height calibration, i.e., measuring a reference sample at known relative heights, is well established [ 20 , 21 ].…”