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.
Highlights
Gaussian Laser beam has been widely used in the field of lighting [1], detection [2], and satellite communication [3]
This paper has proposed an integrated double-sided random microlens array (D-rMLA) fabricated by double-sided expo5
This paper has proposed an integrated D-rMLA fabricated by double-sided exposure uniformity of the homogenized spot for the laser beams with wavelengths of 650 nm (R), technique for laser beam homogenization
Summary
Gaussian Laser beam has been widely used in the field of lighting [1], detection [2], and satellite communication [3]. In order to eliminate the influence of interference on the homogenized spot, researchers propose to employ the random phase plate (RPP) or the multifocal MLA to modulate the laser beam Both of these methods disturb the coherence between sub-beams by modulating the phase, but they are implemented in different ways. Compared to the traditional MLA homogenization system, the structure greatly reduced the diffraction effect and achieved a highly uniform beam profile This method is only applicable to the laser beam with a larger diameter, since the aperture of the sub-lens is on the order of millimeter. The mai interference fringes between are disturbed to 2obtain homogenized spots with rangements of this papersub-beams are as follows: Section describes the principle and simul high uniformity and energy utilization rate.
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