Heuristic self-photography approach for flat-top beam generation with arbitrary beam intensity distribution

• Published in: Optik (Stuttgart) 2020-09, Vol.218, p.164964, Article 164964
• Main Authors: Chang, Rong-Shing, Chen, Chi-Shuo, Lee, Cheng-Lung, Cui, Yujia, Chung, Wei-Ju, Hsu, Ian C.
• Format: Article
• Language: English
• Subjects: Flat-top beam; Hurter–driffield curve; Laser beam shaping; Photography
• ISSN: 0030-4026; 1618-1336
• DOI: 10.1016/j.ijleo.2020.164964

Flat-top beam (FTB) is a type of laser illumination with broad applications. To achieve an easily accessible and cost-effective flat-top intensity profile, a self-photography approach was developed in this study. Utilizing the linear region of the Hurter–Driffield (H&D) curve, we developed an analytical formulation and simulation approach for FTB power optimization with a Gaussian beam (GB) and other intensity profiles. Notably, when a GB profile was used, the maximum transmission efficiency of an FTB depended on the lowest photographic density within the linear region of the H&D curve. Various beam profiles and experimental conditions were evaluated through numerical simulations. We performed experiments to verify the simulation results, which exhibited power efficiency of up to 14.89 % when using a GB. Current beam reshaping techniques use phase modulation; our self-photography method provides an alternative approach to generating uniform illumination with arbitrary intensity profiles, regardless of beam coherence properties. This newly developed cost-effective film approach can be easily incorporated into systems without excessive additional components. This straightforward implementation can be adapted for various illumination needs, such as high-order beam modes and multiple beam sources.