Integrated Double-Sided Random Microlens Array Used for Laser Beam Homogenization

Abstract

Double microlens arrays (MLAs) in series can be used to divide and superpose laser beam so as to achieve a homogenized spot. However, for laser beam homogenization with high coherence, the periodic lattice distribution in the homogenized spot will be generated due to the periodicity of the traditional MLA, which greatly reduces the uniformity of the homogenized spot. To solve this problem, a monolithic and highly integrated double-sided random microlens array (D-rMLA) is proposed for the purpose of achieving laser beam homogenization. The periodicity of the MLA is disturbed by the closely arranged microlens structures with random apertures. And the random speckle field is achieved to improve the uniformity of the homogenized spot by the superposition of the divided sub-beams. In addition, the double-sided exposure technique is proposed to prepare the rMLA on both sides of the same substrate with high precision alignment to form an integrated D-rMLA structure, which avoids the strict alignment problem in the installation process of traditional discrete MLAs. Then the laser beam homogenization experiments have been carried out by using the prepared D-rMLA structure. The laser beam homogenized spots of different wavelengths have been tested, including the wavelengths of 650 nm (R), 532 nm (G), and 405 nm (B). The experimental results show that the uniformity of the RGB homogenized spots is about 91%, 89%, and 90%. And the energy utilization rate is about 89%, 87%, 86%, respectively. Hence, the prepared structure has high laser beam homogenization ability and energy utilization rate, which is suitable for wide wavelength regime.

Numerical Simulation of Enhancement of Superficial Tumor Laser Hyperthermia with Silicon Nanoparticles

“…This beam shape is typical for hyperthermia carried out by light-emitting diodes [53] or lasers generating in multimode regime [54]. In these cases, circular homogeneous intensity distribution can be achieved with the help of laser radiation homogenizers, enabling a spatially flat-top laser spot of non-polarized laser radiation (see, e.g., [55]). Applying a homogeneous beam seems to be more practical due to the more homogeneous transversal distribution of the intensity as compared to alternatively employed Gaussian beams.…”

Single Quasi–Symmetrical LED with High Intensity and Wide Beam Width Using Diamond–Shaped Mirror Refraction Method for Surgical Fluorescence Microscope Applications

“…Table 2 lists the comparison results for the proposed and existing methods [32,[40][41][42][43]. Table 3 compares the proposed method with the previous method while matching their WD values.…”

Alignment error modeling and control of a double-sided microlens array during precision glass molding

“…Double-sided microlens arrays (DSMLAs) work to homogenize laser beams by dividing the incident nonuniform beam into multiple beams and superimposing these beams using a focusing lens. DSMLAs exhibit simple structures, low transmission losses, high damage thresholds, and low requirements for incident light intensity distribution, making them widely used for laser beam homogenization 1 , 2 and structured illumination 3 , 4 . Furthermore, DSMLAs are aligned with the development direction of microelectromechanical systems (MEMSs) due to their attributes of miniaturization, integration, and light weight.…”