When the traditional processing method is used to process hard and brittle monocrystalline silicon, it will encounter a variety of problems, so it is necessary to use laser processing method. Laser processing is a new processing method, and there are few relevant studies on laser processing silicon convex microlens array, and no polishing. Therefore, the morphologies of silicon microlens arrays fabricated by femtosecond laser are studied in this paper. The results show that when the fixed green light is 100KHz, the power is about 36W, and the speed is 1500mm/s, the 3D dynamic processing effect of femtosecond laser is better. The morphology compensation research is carried out, and the surface roughness is greatly improved by using mirror jet polishing.
Numerical simulation of glass molding and research on material viscoelastic have become increasingly important with the deepening of glass molding research for optical devices. In this study, we developed an accurate and efficient numerical simulation method for the glass aspherical lens molding process. According to the FEM simulation results of aspheric lens molding, gas trapping occurred in the molding of preforms of size 5 mm, which was consistent with the experimental results. The molded lens was tested by profilometer and a gas trapping area of about 3 microns deep and hundreds of microns wide existed at the top of the lens, which was also consistent with the FEM analysis results. The consistency of the FEM predicted results with the experimental results illustrated that the Coupled Eulerian-Lagrangian (CEL) method can be used for the prediction of the gas trapping phenomenon in aspheric lens molding. This study provides a reference for the numerical simulation and process optimization of the glass molding of optical device
Precision glass molding (PGM) technology is one of the best methods for processing optical glass lenses, but the incomplete filling in the PGM process has a negative impact on the accuracy of the fabricated aspherical glass microlenses (AGM). It is found that the main reason for this phenomenon is trapped gas between the mold and the glass preform during PGM process. This study observed the gas trapping morphology of the prepared AGM, theoretically analyzed and numerically simulated the formation of trapped gas, and developed the method of eliminating trapped gas induced filling defects. Specifically, in the molding process, the gas trapped in the molding chamber is difficult to be released. We proposed to lower the temperature of the glass and mold to make the softened glass return to the glass state, so that the gas can flow between the two surfaces to achieve the purpose of releasing the trapped gas. When the pressure gas is released, a second molding can effectively improve the filling effect. We call this process cooled down molding (CDM). Experimental results prove that CDM can effectively improve the filling rate in a short period of time and filling defects can be effectively eliminated by designing CDM molding process.
Microlens elements are widely applied in various beam processing applications. However, due to the geometric limitations of the cutting tool and the degrees of freedom of the machine tool, the traditional cutting strategy cannot be employed to fabricate high quality large-vector height microlens. In this paper, a method based on the tool swing cutting and stitching processing is presented. The interference situation and the relationship between the tool parameters and microlens vector height are analyzed. The analysis shows that this method can improve the microlens vector height by about 2 times compared to the slow tool servo. Then the influence of tool setting error on stitching accuracy is studied, and an accurate tool setting method combining CCD tool setting and trial cutting is proposed. Finally, the microlens are experimentally machined to reveal that this method is possible to fabricate microlens with large-vector height and high surface quality.
Microlens elements are widely applied in various beam processing applications. However, due to the geometric limitations of the cutting tool and the degrees of freedom of the machine tool, the traditional cutting strategy cannot be employed to fabricate high quality large-vector height microlens. In this paper, a method based on the tool swing cutting and stitching processing is presented. The interference situation and the relationship between the tool parameters and microlens vector height are analyzed. The analysis shows that this method can improve the microlens vector height by about 2 times compared to the slow tool servo. Then the influence of tool setting error on stitching accuracy is studied, and an accurate tool setting method combining CCD tool setting and trial cutting is proposed. Finally, the microlens are experimentally machined to reveal that this method is possible to fabricate microlens with large-vector height and high surface quality.
The majority of current microfluidic flow cytometers were fabricated by a tractable material, PDMS (Polydimethylsiloxane), which exhibited unsatisfactory optical performances. In this work, we firstly presented an all-glass microfluidic flow cytometer (agFCM) which remarkably improved the optical performance and corresponding blood cell detection accuracy.Picosecond laser was introduced to pattern microfluidic channels, on-chip optical waveguides and on-chip micro-lens on a glass substrate (made with fused silica). The glass debris and burrs caused by laser machining were removed from microfluidic channels by ultrasonic cleaning and CO2 laser reflux respectively. The fabricated glass micro-channel with on-chip lens was sealed by bonding another glass layer to form the agFCM chip. The experimental results demonstrated that, compared with PDMS based devices, agFCM chip improved the optical performances as follows: 1) Scattering haze of material surface was reduced from 50% to 1.4%, effective light transmittance has increased5%.2) the focused excitation spot in detecting area was reduced from 3.60 to 2.64μm. 3) The coupled optical loss of the chip waveguide is reduced to less than 1dB.To sum up, introducing glass as chip material improved the signal to noise ratio by 0.66dB.The performances of agFCM were verified by microsphere experiments. As expected, the improved optical parameters of agFCM resulted in related improvement on detecting accuracy.
To manufacture high precision optical glass microstructures, finite element simulation and experiments of precision glass molding (PGM) are carried out to study the influence of relaxation effect on internal stress and deformation of the glass material. Two kinds of microstructures including microgrooves and micropyramids are fabricated by PGM. First, a two-dimensional axisymmetric finite element model of the PGM is established, and three kinds of molding schemes are put forward and analyzed, including quick molding and holding for a period of time, molding with low speed, molding by gravity. The advantages and disadvantages of the three schemes are also analyzed. Second, the microgrooves are fabricated using the scheme of molding by gravity, and then the existing problems are discussed. Finally, the micropyramids are fabricated by the low speed molding method, and the forming profiles are compared.
With the booming of the curved glass shell and curved panel on the smart phone, the development of 3D curved glass molding process, mold and equipment are fairly promoted. This paper introduces a self-developed full-motor-driving precision molding machine’s developing course. Seven different molding stations using electric actuators as molding axes devices are designed in molding chamber to gives good production efficiency and adaptation of complex process to the molding machine. The maximum molding force and the highest molding temperature is up to 5000N and 800oC, respectively, which satisfies different production requirements. The control unit is built based on the industrial computer in the console and consists of two parts: numerical control system and temperature control system. The control unit can control the molding speed, depth, time directly while the molding force and temperature are controlled by the mean of feedback system. A 3D curved glass molding experiment is carried out by using the machine and graphite mold and finally the 3D curved glass is produced. This result shows that the precision molding machine has achieved the designed functions to manufacture the 3D curved glass and other different complex optical components.
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