Fourier Ptychography-based VCSEL array spots imaging quality enhancement

The Vertical-Cavity Surface-Emitting Laser (VCSEL) is a promising laser source in the optical communication and 3-D sensing for its low threshold current, low power consumption and fast data throughput. To assess the performance of the VCSEL chip, the near-field and far field spots of VCSEL are recorded via an optical microscopic system to calculate the parameters such as uniformity, energy, divergence angle and so on. However, the VCSEL spot analysis of the near field requires extremely high resolution whereas the current detector or the optical system can barely satisfy this demand. To this end, the author applies one method referred as Fourier Ptychography (FP), which is a phase retrieval algorithm merging redundant information into a high spatial band product result, aiming to enhance the near-field VCSEL spot resolution to achieve more accurate parameters. By rotating the illumination angle of VCSEL, multiple angle-varied spot information is captured, then apply FP to fetch an enhanced spot image. Experiment results indicate that our method can greatly improve the spot imaging quality and be of some help for the data analysis.