Contributions of Kinematics and Viscoelastic Lap Deformation on the Surface Figure during Full Aperture Polishing of Fused Silica

2008 ◽  
Author(s):  
Tayyab Suratwala ◽  
R. Steele ◽  
M. Feit
Keyword(s):  
Fused Silica ◽  
Surface Figure

Improvement of Surface Figure in the Polyurethane Pad Continuous Polishing Process

2013 ◽  
Vol 319 ◽  
pp. 107-112 ◽  
Author(s):  
De Feng Liao ◽  
Heng Zhao ◽  
Zhi Gang Yuan ◽  
Rui Qing Xie
Keyword(s):  
Velocity Distribution ◽  
Pressure Distribution ◽  
Rotation Speed ◽  
Fused Silica ◽  
Elastic Response ◽  
Polishing Process ◽  
Uniform Velocity ◽  
Pressure Distributions ◽  
Driving Wheel ◽  
Surface Figure

Primary factors determining surface figure of optics, including the velocity and pressure distributions, have been analyzed and improving methods provided accordingly for the pad continuous polishing (CP). With a septum on the exterior of the workpiece pre-pressing the pad, the inevitable depression on the edge of the workpiece incurred by the elastic response of the pad has been relieved obviously. By introducing the driving wheel system, the rotation speed of the septum & workpiece can be regulated and adjusted to that of the lap/pad, which produces a uniform velocity distribution on the polishing surface. Diamond conditioners with ring & disk patterns are employed to planarize the annular polyurethane pad and hence uniformise the pressure distribution on the workpiece/pad interface. Polishing experiments (Fused silica flat, 320 mm in diameter x 30 mm thick) conducted on the typical CP machine have demonstrated advantages of these methods.

SEM analysis of DC magnetron sputtered beryllium films

1988 ◽  
Vol 46 ◽  
pp. 960-961
Author(s):  
E. F. Lindsey ◽  
C. W. Price ◽  
E. L. Pierce ◽  
E. J. Hsieh
Keyword(s):  
Fine Structure ◽  
Electron Emission ◽  
Secondary Electron ◽  
Low Voltage ◽  
Ion Beam ◽  
Secondary Electron Emission ◽  
Sem Analysis ◽  
Fused Silica ◽  
Grain Structure ◽  
Silica Substrate

Columnar structures produced by DC magnetron sputtering can be altered by using RF biased sputtering or by exposing the film to nitrogen pulses during sputtering, and these techniques are being evaluated to refine the grain structure in sputtered beryllium films deposited on fused silica substrates. Beryllium is brittle, and fractures in sputtered beryllium films tend to be intergranular; therefore, a convenient technique to analyze grain structure in these films is to fracture the coated specimens and examine them in an SEM. However, fine structure in sputtered deposits is difficult to image in an SEM, and both the low density and the low secondary electron emission coefficient of beryllium seriously compound this problem. Secondary electron emission can be improved by coating beryllium with Au or Au-Pd, and coating also was required to overcome severe charging of the fused silica substrate even at low voltage. The coating structure can obliterate much of the fine structure in beryllium films, but reasonable results were obtained by using the high-resolution capability of an Hitachi S-800 SEM and either ion-beam coating with Au-Pd or carbon coating by thermal evaporation.

Investigation of fused silica dynamic behaviour

2006 ◽  
Vol 134 ◽  
pp. 929-934 ◽  
Author(s):  
F. Malaise ◽  
J.-M. Chevalier ◽  
I. Bertron ◽  
F. Malka
Keyword(s):  
Dynamic Behaviour ◽  
Fused Silica

Minimizing residual spectral drift in laser diode bars using femtosecond-written volume Bragg gratings in fused silica

2017 ◽  
Vol 42 (3) ◽  
pp. 623 ◽  
Author(s):  
Daniel Richter ◽  
Malte P. Siems ◽  
Wilko J. Middents ◽  
Maximilian Heck ◽  
Thorsten A. Goebel ◽  
...  
Keyword(s):  
Laser Diode ◽  
Bragg Gratings ◽  
Fused Silica ◽  
Volume Bragg Gratings
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