Research on the Technology of Detection for the Tip Arc Waviness

of Diamond Tool Based on AFM

Xiaobin Yue

Supervisor: Min Xu

       The technology of single point diamond turning is an important branch of the field of ultra-precision cutting technology. It has a great practical needs and long-term significance in military national defense and economic construction. Single point diamond tool is one of the basic elements of ultra-precision cutting. Research results show that tip arc waviness of diamond tool has an important impact on surface quality of ultra-precision machining, in particular, the surface morphology of micro-geometry. Multi-point on the profile of tool edge will be involved in the cutting process of aspheric surface. The contour precision of the workpiece will be seriously influenced because tool tip arc waviness will be reflected to the contour of workpiece. Therefore, tool tip arc waviness is an important technical parameter for characterization of high precision diamond cutting tool. 

       The tip arc waviness of high precision diamond tool is generally between 50-200nm (wrap angle of 60 degree), the high precision index of tip arc waviness cannot be effectively measured by the existing optical microscopic method (300nm resolution) which is limited by the optical diffraction effect. At the same time, there is no relevant standard for measurement the tip arc waviness of diamond tool in 100nm level at home and abroad. Therefore, there are still two major difficulties on measuring the tip arc waviness of diamond tool: first, conventional contour measure equipment is not able to measure edge profile effectively, and second, evaluation theory or standard for the tip arc waviness of diamond tool is not unified. 

       Based on the analysis of key technology for measuring the tip arc waviness of diamond tool, the detection system of tool tip arc waviness was developed based on atomic force microscope (AFM) and ultra-precision spindle in this project. In order to achieve the accurate measurement of tool tip arc waviness in 100nm level, eccentric adjuster in sub-micron level precision was designed, and radial rotation error of aerostatic bearing was in the range of 50nm, the special data acquisition and analysis software was also developed. Finally, the accurate measurement of tool tip arc waviness in 100nm level has achieved based on the existing national and international standards, the experiment results show that system detection accuracy stabilizes in 50nm.

       This project has researched on the exploration of tool tip arc waviness of diamond cutting tool through theoretical analysis and experiments. The successful development of this detection system established the critical foundation for measuring the tip arc waviness of diamond tool. That results and conclusions obtained can provide a reference for evaluating quality of diamond tool and technical support for accurate measurement of micro structural profile in nanometer level.

References:

[1]R.L.Mceachern,C.E.Moore, and R.J.Wallace. The Design, Performance, and Application of an Atomic Force Microscope-based Profilometer. J.Vac.Sci.Technol.A.1995, (13):983-989

[2] X.S.Zhao,T.Sun,Y.D.Yan,et al. The Measurement of Roundness and Sphericity of the Micro Sphere Based on Atomic Force Microscope. Key Engineering Materials. 2006,315-316:796-799

[3]D.L.Martin,A.N.Tabenkin and F.G.Parsons.Precision Spindle and Bearing Error Analysis. International Journal of Machine Tools & Manufacture.1995,(2):187-193

[4]L.Zhu,Y.Ding and H.Ding. Algorithm for Spatial Straightness Evaluation Using Theories of Linear Complex Chebyshev Approximation and Seminfinite Linear Programming.Journal of manufacturing science and engineering.2006,128(1):167-174

[5] J.A.Lipa,G.J.Siddal. High Precision Measurement of Gyro Rotor Sphericity. Precision Engineering.1980,2(3):12-26

Strong Coupling of Hybrid and Plasmonic Modes for High Q Plasmonic Resonance in Liquid Core Optical Micro-Bubble Cavities

Qijing Lu

Supervisor: Liying Liu

       Plasmonic resonators are important fundamental elements in plasmonics [1]. In addition to their great potential to miniaturize device size, the strong local field enhancement in plasmonic resonators also allows many applications such as ultrasensitive biosensors [2-6]. However, due to the strong absorption of light in metal, plasmonic resonators usually have low quality factor Q. Even for a plasmonic resonator obtained by coating high quality metal film on an ultra-high Q optical microcavity, its theoretical Q factor is only just around a thousand . Approaches have been explored to suppress light absorption, mainly through coupling. Coupling a plasmonic resonance mode with a high Q whispering gallery mode (WGM) successfully boosts Q value . Coupling of surface plasmon polariton (SPP) modes on both sides of a metal film generates low-loss long range SPP resonant modes . However, efficient coupling requires phase matching of the two resonant modes, which is not easily satisfied in most of the reported cases, solid experimental demonstration is rarely seen as well. Not mention that the designed plasmonic resonators can be hardly excited because the effective refractive index of a plasmonic resonance is very close to the environmental refractive index, conventional excitation methods do not work well.

       In this paper, we report a new scheme to efficiently couple and excite the plasmonic resonance mode in a liquid core micro-bubble resonator (MBR). MBRs support ultra-high Q WGMs with very small mode volume , they can be filled with liquid, becoming a perfect microfluidic lab-on-a-tube device for many applications such as bio-chemical sensing. When a metal film is coated on the inside-wall of a silica micro-bubble, plasmonic resonance modes form on liquid-metal interface and metal-silica interface. In the meantime, the silica bubble wall also supports high Q WGMs that can be easily excited by using a tapered fiber contacted with the bubble outside-wall. Here we show that strong coupling between the plasmonic resonance mode on metal-silica interface with photonic WGM in the bubble wall is possible because phase matching condition is satisfied. On the other hand, strong coupling between the interior plasmonic mode with the hybrid plasmonic-photonic resonance mode can also be achieved by adjusting the refractive index of the liquid inside the bubble. With this, light can be efficiently launched into plasmonic resonance mode on the inner side of the bubble. Our experimental results clearly revealed the strong coupling process.

References:

1.    E. Ozbay, "Plasmonics: Merging photonics and electronics at nanoscale dimensions," Science 311, 189-193 (2006).

2.    S. I. Bozhevolnyi, V. S. Volkov, E. Devaux, J. Y. Laluet, and T. W. Ebbesen, "Channel plasmon subwavelength waveguide components including interferometers and ring resonators," Nature 440, 508-511 (2006).

3.    M. T. Hill, Y. S. Oei, B. Smalbrugge, Y. Zhu, T. De Vries, P. J. Van Veldhoven, F. W. M. Van Otten, T. J. Eijkemans, J. P. Turkiewicz, H. De Waardt, E. J. Geluk, S. H. Kwon, Y. H. Lee, R. Notzel, and M. K. Smit, "Lasing in metallic- Coated nanocavities," Nature Photonics 1, 589-594 (2007).

4.    R. F. Oulton, V. J. Sorger, T. Zentgraf, R. M. Ma, C. Gladden, L. Dai, G. Bartal, and X. Zhang, "Plasmon lasers at deep subwavelength scale," Nature 461, 629-632 (2009).

5.    M. Khajavikhan, A. Simic, M. Katz, J. H. Lee, B. Slutsky, A. Mizrahi, V. Lomakin, and Y. Fainman, "Thresholdless nanoscale coaxial lasers," Nature 482, 204-207 (2012).

6.    W. Kubo, and S. Fujikawa, "Au Double Nanopillars with Nanogap for Plasmonic Sensor," Nano Letters 11, 8-15 (2011).

Athermalization Design ofMedium Wave Infrared Optical System

Junhua Wang

Supervisor: Min Xu

Frequently, opticalsystems must perform over wide temperature range. Due to the thermal expansion and the change of the index of refraction of the lens material with temperature, the performance of the system is affected. This is especially pronounced in the infrared region, where most materials suffer from a high dn/dt, the change of index with temperature[1].The main effect of a temperature change to the optical system is a change of the back focal length and a change of the focal length. In order to avoid these changes one has to athermalize the system[2].

To maintain an acceptable image quality, in many cases refocusing will be necessary. This can be accomplished mechanically or optically. Specifically, the mechanical adjustment can be done manually or by other means, such as feedback servo systems and others[3]. Optically, the compensation can be achieved by selecting suitable optical materials and element powers.Optical passive athermalizationcan be achieved with special combinations of lens materials. An athermalizedachromat consists of three lenses, or two lenses with one of them diffractive.Two of the materials have quite highthermal coefficient of refractive index, the third material has a quite low thermal coefficient[4]. The lens made of the third material has negative power. For an optical passive athermalization of a complete system, for example an afocal with an imager or a reimager, a large number of lens are needed[5].

Based on the principle of passive optical athermalization, a medium wave infrared optical system is designed for working at -40℃~+60℃. A 128×128 focal plane array (FPA) detector as image plane is used in the system. The system has a field-of-view of 6° and a relative aperture of f/2 at 3.7~4.8μmwith 100% cold shield efficiency. The design result shows that the infrared optical system can achieve good imaging quality over the temperature range -40℃~60℃.

Key words: athermalization, infrared optical system, Optical passive athermalization,

References

[1] Jamieson T H.Thermal effects in optical systems. Journal of the Optical Society of America . 1998

[2]A.Mann, Infrared Optics and zoom lense[M]. 2009, Bellingham, Washington USA:SPIE

[3] T. Baak.Thermal Coefficient of Refractive Index of Optical Glasses. Journal of the Optical Society of America . 1969

[4] J.L.Rayces,L.Lebich.Thermal Compensation of Infrared Achromatic Objectives with Three Optical Materials. Proceedings of SPIE the International Society for Optical Engineering . 1990

[5] M.Robert, Infrared Lenses, US Patent 4679891(1987).

Enhancement of the photoluminescence of ZnO thin films after the passivation using gas plasma

Da Liu

Supervisor: Jian Sun

       As a II-VI compound semiconductor with wide direct band gap, ZnO is very potential to be applied in various fields, such as short-wavelength optoelectronic devices [1-3]. Since reproducible p-type ZnO has not yet been developed, researchers nowadays use n-type ZnO on other available and comparable p-type materials, Si as an example, to study the properties of ZnO heterojunctures [3].

       To enhance the luminescence and suppress the defect emissionsof ZnO nanostructure including thin films, gas plasma has been introduced to passivate ZnO materials. Among these gases, H₂ plasma is most commonly used to decrease the deep level emission and enhance near band emission [4], while O₂ plasma is also used to modify the photoluminescence properties[5]. But up to now, the effect of Ar plasma treatment has not been reported or explained in detail.

       In this work, various kind of gas plasma have been used to passivate ZnO thin films whether annealed or not after deposited using ECR-PLD system on single crystalline Si substrate. After that, these samples have been characterized by XRD and room temperature PL. It was found that the RTPL peak at ~380nm has increased by a multitude after the sample was treated by Ar plasma with a slight red-shift, while the peak has decreased after treated by N₂ or O₂. Defect emission has also been changed after treatment. Detailed work concerning changing of parameters is in processing.

References:

1.    Hwang, D.-K., et al., ZnO thin films and light-emitting diodes. Journal of Physics D: Applied Physics, 2007. 40(22): p. R387-R412.

2.    Djurisic, A.B. and Y.H. Leung, Optical properties of ZnO nanostructures. Small, 2006. 2(8-9): p. 944-61.

3.    Özgür, U., D. Hofstetter, and H. Morkoc, ZnO Devices and Applications: A Review of Current Status and Future Prospects. Proceedings of the IEEE, 2010.

4.    Bang, J.-H., et al., Effects of additive gases and plasma post-treatment on electrical properties and optical transmittance of ZnO thin films. Thin Solid Films, 2010. 519(5): p. 1568-1572.

5.   Dev, A., et al., Stable enhancement of near-band-edge emission of ZnO nanowires by hydrogen incorporation. Nanotechnology, 2010. 21(6): p. 065709.

6.    Jiang, S., et al., Tunable photoluminescence properties of well-aligned ZnO nanorod array by oxygen plasma post-treatment. Applied Surface Science, 2014. 289: p. 252-256.

Time: 6:30 pm, Wednesday, 2014.12.31

Location:Optical Building. Room 525