A new technology for microlens array fabrication is presented. The technology is based on creation of the initial microstructures on fused silica by laser indirect method, and the following reflow process of these structures made by CO 2 laser action. Microlens arrays with diameter of microlens equal to 150 µm are fabricated. The focal length of microlens varies from 5 up to 5 mm. Profiles of formed microlens correspond to circle equation.
Ключевые слова: fused silica microstructuring, microlens array, LIBBH, CO 2 laserIntroduction. At present different arrays of microoptical elements are traditionally used for transformation and processing of optical signals, for fiber-optical connections and integrated optical control systems [1] as well as to transform of intensity distribution in laser technology [2,3]. As the array of microoptical elements means a set of modified regions, located in a certain order on glass surface [2,4] and can be called microlens array (MLA). Such MLAs have a special arrangement and a given filling rate within the array, all these specifications depend on the problem to be solved with the final array.Not only optical-physical specific requirements are imposed on MLA in particular application, but also requirements on the surface quality in general. Particular attention is paid to the fabrication of MLAs on materials of traditional optics as silicate glass [5]. Thus, the developers' preferences are given to fused silica, which can be characterized by high light transmittance in wavelength range of 200-2500 nm and high chemical, thermal, and radiation resistance [6].Among the traditional technologies of MLAs fabrication on glass surface, the best known technologies are: photolithography [7], ion etching [8], hot embossing process [9], and so on. These technologies can be characterized not only by high quality of fabricated MLAs and high reproducibility, but also use multistage processing; manufacturing of MLAs with low numerical aperture (NA) presents difficulties when the technology is employed [7]. Currently, great attention is paid to MLAs fabrication with the usage of laser technology. It is also called as direct laser beam writing, which is based on strong absorption of CO 2 laser radiation [10], UV radiation [11] by glass , or on interaction with ultrashort laser pulses [12].Combined laser-induced technologies based on strong absorption of laser radiation by inorganic [13,14] or organic [15,16] solutions and metals [17,18] contact with the back side of the glass plate are widely spread today. The most popular technologies are laser-induced backside wet etching (LIBWE) [16,[19][20][21][22], laser-induced backside dry etching (LIBDE) [17,18,23], laser induced plasma assisted ablation (LIPAA) [24][25][26], and lased-induced black-body heating (LIBBH). The last one has been developed at Laser Technology Department of ITMO University [27][28][29][30][31]. Various arrays of microoptical elements formed on fused silica surface according to this technology include random phase plates [27], si...
