Radius of curvature measurements for laser beams: A simple method

Optik ◽  
2006 ◽  
Vol 117 (4) ◽  
pp. 173-176 ◽  
Author(s):  
Lingyu Wan ◽  
Liren Liu ◽  
Mingli Zhang ◽  
Zhu Luan
1986 ◽  
Vol 25 (20) ◽  
pp. 3731 ◽  
Author(s):  
Rufino Diaz-Uribe ◽  
Alejandro Cornejo-Rodriguez

2004 ◽  
Author(s):  
Devendra Karodkar ◽  
Neil Gardner ◽  
Brent C. Bergner ◽  
Angela Davies

1980 ◽  
Vol 15 (3) ◽  
pp. K25-K27
Author(s):  
E. Zschech ◽  
G. Merz ◽  
W. Blau ◽  
K. Kleinstück

2003 ◽  
Vol 18 (2) ◽  
pp. 423-432 ◽  
Author(s):  
G.F. Iriarte ◽  
F. Engelmark ◽  
M. Ottosson ◽  
I.V. Katardjiev

In this work, a systematic study of the influence of five deposition parameters, i.e., process pressure, substrate temperature, target power, and substrate bias, as well as gas composition on the residual stress in fully textured polycrystalline aluminum nitride thin films deposited on Si(100) wafers using the reactive sputtering method was performed. Post-growth residual stress measurements were obtained indirectly from radius of curvature measurements of the wafer prior to and after deposition. Two different techniques were used to determine the curvature: an optically levered laser beam and an x-ray diffraction method. Stresses in both cases were then evaluated using the Stoney formulation [G.G. Stoney, Proc. R. Soc. (London)A82,172 (1909)]. Both methods give similar results, with slight quantitative differences. The existence of a transition region between tensile and compressive stress previously reported in the literature is also confirmed. The transition is shown to be strongly dependent on the process parameters. Optimal films regarding stress were grown at 2 mtorr, 900 W at the target, a 20/45 Ar/N2gas mixture, and floating potential at the substrate. The substrate temperature did not influence the measured internal stress in the films.


2012 ◽  
Vol 523-524 ◽  
pp. 1059-1064
Author(s):  
Nobuyuki Watanabe ◽  
Kozo Taguchi

Optical trapping is a technique that is used to capture, translate, and manipulate microscopic particles, such as dielectric microspheres and cells. This cell manipulation and examination technology can be integrated on a Lab-on-a-Chip device. We have already developed an optically vibration system. The optical vibration system was formed using a temperature stabilized 1480nm cw diode laser. The output of laser light was coupled into optical fibers, which had optical connectors at these fiber ends. The fiber end had a hemispherical micro-lens with 5μm radius of curvature for focusing the laser beam emerging from the optical fiber end. These trapping fibers were attached to xyz manipulators and were inserted into a sample cell at an angle of 35 degrees. The trapped microsphere, 10μm diameter polystyrene particle (refractive index 1.59), could be optically vibrated by controlling laser power emerging from optical fibers. We theoretically analyzed the optical forces exerted on a microsphere by laser beams. Its operating principle is based upon the conservation of photon momentum carried by the incident laser light on a trapped microsphere. From these theoretical results, we verified that our proposed optical manipulation technique was useful for the manipulation of biological cells.


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