Surface Profile Error Measurement For Small Rotationally Symmetric Surfaces

1989 ◽  
Author(s):  
Russ Palum
Keyword(s):  
Surface Profile ◽  
Error Measurement ◽  
Profile Error ◽  
Rotationally Symmetric

Influence of Surface-Profile Error of Larger Mirror on Aberrations Characteristics of Optical System

2013 ◽  
Vol 33 (4) ◽  
pp. 0422002
Author(s):  
庞志海 Pang Zhihai ◽  
樊学武 Fan Xuewu ◽  
陈钦芳 Chen Qinfang ◽  
马臻 Ma Zhen ◽  
邹刚毅 Zou Gangyi
Keyword(s):  
Optical System ◽  
Surface Profile ◽  
Profile Error

Generation of Milled Surfaces Including Tool Dynamics and Wear

1993 ◽  
Vol 115 (3) ◽  
pp. 245-252 ◽  
Author(s):  
F. Ismail ◽  
M. A. Elbestawi ◽  
R. Du ◽  
K. Urbasik
Keyword(s):  
Tool Wear ◽  
Flank Wear ◽  
Mechanistic Model ◽  
Surface Profile ◽  
Surface Generation ◽  
Profile Error ◽  
Peripheral Milling ◽  
Characteristic Features ◽  
Tool Dynamics ◽  
Good Agreement

In this paper, a mechanistic model for surface generation in peripheral milling, which includes the effects of cutter vibrations, run out, as well as flank wear is presented. The surface roughness parameters, and characteristic features of the surface profile were examined using computer simulations. The results of the simulation runs were verified experimentally and a good agreement was obtained. The results demonstrated clearly the importance of including tool wear in surface generation predictions. It has been shown that the model is capable of predicting the smearing of the surface generated due to increased tool wear. Also, the ploughing force acting on the wear land considered in the model influenced the resulting profile error significantly.

Measurement of the Straightness of a Leadscrew-Driven Precision Stage

2005 ◽  
Vol 295-296 ◽  
pp. 259-264 ◽  
Author(s):  
Yoshikazu Arai ◽  
Wei Gao ◽  
S. Kiyono ◽  
Tsunemoto Kuriyagawa
Keyword(s):  
Data Processing ◽  
Surface Profile ◽  
Probe Method ◽  
Profile Error ◽  
Precision Stage ◽  
Improved Technique ◽  
Straightness Error ◽  
Periodicity Component ◽  
Short Periodicity ◽  
Probe Spacing

This paper describes a multi-probe method for measuring the straightness error of a leadscrew-driven stage. Two displacement probes are employed to scan a flat artifact mounted on the stage. The surface profile error of the flat artifact is separated from the straightness error of the stage in a differential output of the probes. The straightness error can thus be obtained accurately from an integration operation of the differential output without the influence of the surface profile error. An improved technique of data processing is adopted for measurement of straightness error components with periodicity shorter than the probe spacing. The influence of the angular error of the stage is compensated for by using the result measured by an autocollimator. Experiments of straightness measurement of a leadscrew-driven stage with a lead of 1 mm were carried out by using two flat artifacts with different degrees of precision. The successful detection of the short-periodicity component of the straightness error with a periodicity equal to the lead indicated the feasibility of the multi-probe method.

402 Measurement of an Aspherical Surface Profile : Self-Calibration Method for Profile Error of Probe Sphere

2005 ◽  
Vol 2005.40 (0) ◽  
pp. 140-141
Author(s):  
Atsushi SHIBUYA ◽  
Yoshikazu ARAI ◽  
Wei GAO ◽  
Hiroki SHIMIZU ◽  
Satoshi KIYONO
Keyword(s):  
Surface Profile ◽  
Calibration Method ◽  
Profile Error ◽  
Aspherical Surface ◽  
Self Calibration

Practical Correction of Three Fold Astigmatism in the Philips CM TEM

1996 ◽  
Vol 54 ◽  
pp. 418-419
Author(s):  
Arno J. Bleeker ◽  
Mark H.F. Overwijk ◽  
Max T. Otten
Keyword(s):  
Optical Properties ◽  
Phase Contrast ◽  
The Other ◽  
Objective Lens ◽  
Symmetric Part ◽  
A Posteriori ◽  
Contrast Transfer Function ◽  
High Brightness ◽  
Rotationally Symmetric ◽  
Brightness Field

With the improvement of the optical properties of the modern TEM objective lenses the point resolution is pushed beyond 0.2 nm. The objective lens of the CM300 UltraTwin combines a Cs of 0. 65 mm with a Cc of 1.4 mm. At 300 kV this results in a point resolution of 0.17 nm. Together with a high-brightness field-emission gun with an energy spread of 0.8 eV the information limit is pushed down to 0.1 nm. The rotationally symmetric part of the phase contrast transfer function (pctf), whose first zero at Scherzer focus determines the point resolution, is mainly determined by the Cs and defocus. Apart from the rotationally symmetric part there is also the non-rotationally symmetric part of the pctf. Here the main contributors are not only two-fold astigmatism and beam tilt but also three-fold astigmatism. The two-fold astigmatism together with the beam tilt can be corrected in a straight-forward way using the coma-free alignment and the objective stigmator. However, this only works well when the coefficient of three-fold astigmatism is negligible compared to the other aberration coefficients. Unfortunately this is not generally the case with the modern high-resolution objective lenses. Measurements done at a CM300 SuperTwin FEG showed a three fold-astigmatism of 1100 nm which is consistent with measurements done by others. A three-fold astigmatism of 1000 nm already sinificantly influences the image at a spatial frequency corresponding to 0.2 nm which is even above the point resolution of the objective lens. In principle it is possible to correct for the three-fold astigmatism a posteriori when through-focus series are taken or when off-axis holography is employed. This is, however not possible for single images. The only possibility is then to correct for the three-fold astigmatism in the microscope by the addition of a hexapole corrector near the objective lens.

New Feasible Concepts of Aberration Correction for Realizing High-Resolution Electron Microscopes

1990 ◽  
Vol 48 (1) ◽  
pp. 202-203
Author(s):  
H. Rose
Keyword(s):  
Spherical Aberration ◽  
Wave Length ◽  
Electron Wave ◽  
Optical Lens ◽  
Resolution Electron ◽  
Rotationally Symmetric ◽  
Electron Microscopes ◽  
The Cost ◽  
Imaging Performance ◽  
Acceleration Voltage

The imaging performance of the light optical lens systems has reached such a degree of perfection that nowadays numerical apertures of about 1 can be utilized. Compared to this state of development the objective lenses of electron microscopes are rather poor allowing at most usable apertures somewhat smaller than 10-2 . This severe shortcoming is due to the unavoidable axial chromatic and spherical aberration of rotationally symmetric electron lenses employed so far in all electron microscopes.The resolution of such electron microscopes can only be improved by increasing the accelerating voltage which shortens the electron wave length. Unfortunately, this procedure is rather ineffective because the achievable gain in resolution is only proportional to λ1/4 for a fixed magnetic field strength determined by the magnetic saturation of the pole pieces. Moreover, increasing the acceleration voltage results in deleterious knock-on processes and in extreme difficulties to stabilize the high voltage. Last not least the cost increase exponentially with voltage.

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