Tien-Tung Chung

Two-dimensional slicing method to speed up the fabrication of micro-objects based on two-photon polymerization

Generally, a layer-by-layer method along one specific direction (two-and-half-dimensional method) is used to fabricate three-dimensional (3D) microstructures. Ultrathin layers and long processing times are necessary to obtain smooth surfaces in near flat regions of microstructures. In their approach, the authors slice these nearly flat areas along another slicing direction to produce the scanning paths of the laser beam. Several examples, including a microdragon, have been produced to validate that this real 3D method can generate micro-objects with a good balance between surface accuracy and processing efficiency.

Multiplying optical tweezers force using a micro-lever.

This study presents a photo-driven micro-lever fabricated to multiply optical forces using the two-photon polymerization 3D-microfabrication technique. The micro-lever is a second class lever comprising an optical trapping sphere, a beam, and a pivot. A micro-spring is placed between the short and long arms to characterize the induced force. This design enables precise manipulation of the micro-lever by optical tweezers at the micron scale. Under optical dragging, the sphere placed on the lever beam moves, resulting in torque that induces related force on the spring. The optical force applied at the sphere is approximately 100 to 300 pN, with a laser power of 100 to 300 mW. In this study, the optical tweezers drives the micro-lever successfully. The relationship between the optical force and the spring constant can be determined by using the principle of leverage. The arm ratio design developed in this study multiplies the applied optical force by 9. The experimental results are in good agreement with the simulation of spring property.

A 2

This paper presents the design, fabrication, alignment and experimental tests of a 2times2 mechanical optical switch. The key component of the mirror device is fabricated by the MEMS process that coats both sides with an ultrathin high reflection Au/Cr film (thickness less than 1.8 microns and roughness 5.7 nm) to allow double-sided reflection. The mirror is mounted on a thin metal arm, which is switched by a mechanical relay. Compared to the 4-mirror type of single-sided reflector which is used by other 2times2 optical switches, this configuration significantly reduces the size and number of the components. The optical alignment and the component assembly can rapidly be accomplished by two stages: visual coarse alignment and automatic fine alignment. Due to the feature of an adjustable mirror positioning and orientation, insertion losses can be reduced to a very low level. Experimental results show that the insertion losses, crosstalk, switching time and long-cycle test can all meet the Bellcore 1073 specification requirements.

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This paper presents a novel planar diffraction grating interferometer (PDGI), which is based on the principle of diffractive interferometry. The PDGI is composed of two linear diffraction grating interferometers (LDGIs) arranged in orthogonal configuration for simultaneously measuring the two-dimensional displacement of the planar grid, which is mounted on the bottom surface of an XY stage. It adopts a special design in optical path that can increase the alignment tolerance between the optical head and the grid. The signal process circuit and software are also developed, including the pulse count and phase subdivision. The fabricated planar grid has 55 mm×55 mm size and 1740 line/mm. The resolution can reach to 1 nm. Experimental results on an air bearing XY stage showed that even in the normal laboratory environment the standard deviation of measured values can be controlled to within 15 nm for a long stroke up to 25 mm in both axes.

2 Mechanical Optical Switch With a Thin MEMS Mirror

We study the rotation of photo-driven Archimedes screw with multiple blades. The micron-sized Archimedes screws are readily made by the two-photon polymerization technique. Free-floating screws that are trapped by optical tweezers align in the laser irradiation direction, and rotate spontaneously. In this study we demonstrate that the rotation speeds of two-blade-screws is twice the rotation speed of one-blade-screw. However, more complex 3-blade-screws rotate slower than 2-blade-screws due to their limited geometry resolution at this micron scale.

Displacement measurement of planar stage by diffraction planar encoder in nanometer resolution

This paper presents the design, fabrication and testing of a novel 1 ? 4 mechanical optical switch, whose components are fabricated by precision machining and MEMS technologies. The switch uses two relays as the two actuators whose switching direction is perpendicular to each other by an orthogonal arrangement. We adopt a direct fiber-to-fiber principle that aligns the input fiber directly to four output fibers. This configuration eliminates the use of traditional parts such as collimators, turning mirrors or prisms. In addition, due to the use of a fiber holder, the fiber position errors could be reduced to less than 0.27 ?m using the two-stage geometry error reduction principle. We have successfully developed a simple and low-cost switch, which performs like most of the 1 ? 4 mechanical optical switches that dominate the optics communications market. The advantages of our switch are a small size (20 ? 20 ? 25 mm3), low cost, high reliability, and the latching function does not need external force for maintaining the state. The experimental results showed that the insertion losses of the four channels are ch1: 0.68 dB, ch2: 1.49 dB, ch3: 0.71 dB and ch4: 0.97 dB. The switching time is 5 ms, the crosstalk ?80 dB. The reliability tests of the insertion loss after 10?000 cycles in four channels yield ch1: 1.67 dB, ch2: 1.63 dB, ch3: 0.75 dB and ch4: 0.98 dB. The size and the cost of our 1 ? 4 mechanical optical switch are only about 1/5?1/10 and 1/10 of the series-connect-type and prism-type switches, respectively.

Optically driven Archimedes micro-screws for micropump applications: multiple blade design

This paper develops an integrated scanning system for reconstructing 3D color models of general objects. First, a laser scanner is used to digitize the 3D shape of an object. When scanning the darker surface of an object, laser beams with different laser power are emitted onto the object surface to obtain adaptive scan lines, and the scan line with best quality is automatically selected to improve the quality of the scan data. 3D triangular meshes are constructed from scan data points and the 3D surface model of the object can be obtained. Then, a digital camera is used to capture color texture images of the object. A texture mapping method is developed to automatically wrap texture images onto triangular meshes to form the 3D color model of the object. Finally, an integrated scanning system is established by combining a laser scanner and a digital camera. Using this system, 3D color models of two tested objects are reconstructed and good results are obtained.

A novel micro/nano 1 ? 4 mechanical optical switch

This paper presents the design, fabrication and tests of a miniature 1 ? 2 mechanical type optical switch, whose components are fabricated by precision machining and MEMS technologies. The packaging and alignment are integral processes utilizing the CCD image processing technique and PZT-stages controlled technique in association with the optimization software enabling the fiber-to-fiber alignment to low optical loss requirement. Optical fibers in use have the following specifications: single-mode fiber (SMF) outer diameter 125 ?m, core diameter 9??m, zero degree of the fiber tip angle and non-anti-reflection coating. The initial gap of the input and output fibers is 10 ?m. First, we produced a fiber holder and a V-groove by MEMS technology and used a relay as the input fiber switching actuator. Through proper mechanism design, the fiber positioning error can be reduced to below 0.1 ?m. After the optimized alignment process, the results presented that the insertion loss could be controlled to ch1: 0.8 dB, ch2: 1.4 dB at a switching time of 5 ms. The reliability tests demonstrated that the variation of the insertion losses are ch1: 0.04 dB, ch2: 0.02 dB after 10?000 cycle times, and ch1: 0.024 dB, ch2: 0.006 dB throughout 100 switch times after 1?000?000 cycle times. The developed 1 ? 2 optical switch largely reduces the physical size to 1/2?1/3 in comparison with traditional mechanical optical switches, and the cost is only about 1/10?1/20 of the MEMS type optical switches. The advantages of this innovative optical switch are: small size (only about 20 ? 16 ? 7.5 mm3), low cost (only about US

An integrated scanning system for reconstructing 3D color models of general objects

10), high reliability, cross-talk ?80 dB and automatic alignment.

A miniature low cost and high reliability 1 × 2 mechanical optical switch

This paper develops a planar motion stage with high precision, long working range, and nano-positioning accuracy. The stage consists of a stage base, side walls, a carriage supported with eight air bearings, a magnetic suspension control unit, a magnetic actuation unit, and a two- dimensional optical encoder. Configuration design concepts are proposed for better operation characteristics. The structural characteristics of the stage are analyzed by static finite element method. The measurement system for this stage employs the two-dimensional optical encoder for sensing both X and Y positions. The multiple-input and multiple-output controller is used to control four sets of drivers independently.