Aberrations

2019 ◽  
pp. 215-248
Author(s):  
B. D. Guenther
Keyword(s):  
Hubble Space Telescope ◽  
Spherical Aberration ◽  
Chromatic Aberration ◽  
Optical Path Difference ◽  
Path Difference ◽  
Optical Path ◽  
Wavefront Aberration ◽  
Third Order ◽  
The Third ◽  
Field Curvature

Using simple ray tracinig technliques presented in Chapter 6, we demonstrate that a general ray is not focused to the position predicted by paraxial theory. The aberration displayed is spherical aberration. Two methods of measuring aberration: the use of optical path difference to characterize wavefront aberration. The transverse ray coefficients to generate a ray intercept plot. Experimental examples of all the third order aberrations are given. In addition to spherical aberration, they include coma, astigmatism, field curvature, and distortion Only two types of aberration correction are discussed, removal of spherical aberration in the Hubble Space telescope and chromatic aberration. A detailed example of chromatic aberration is given.

Probe size and 5th-order aberration

1987 ◽  
Vol 45 ◽  
pp. 134-135 ◽  
Author(s):  
Zhifeng Shao
Keyword(s):  
Electron Probe ◽  
Spherical Aberration ◽  
Wave Length ◽  
Cylindrical Symmetry ◽  
Electron Wave ◽  
Third Order ◽  
The Third ◽  
Probe Radius ◽  
Small Probe ◽  
Probe Size

A small electron probe has many applications in many fields and in the case of the STEM, the probe size essentially determines the ultimate resolution. However, there are many difficulties in obtaining a very small probe.Spherical aberration is one of them and all existing probe forming systems have non-zero spherical aberration. The ultimate probe radius is given byδ = 0.43Csl/4ƛ3/4where ƛ is the electron wave length and it is apparent that δ decreases only slowly with decreasing Cs. Scherzer pointed out that the third order aberration coefficient always has the same sign regardless of the field distribution, provided only that the fields have cylindrical symmetry, are independent of time and no space charge is present. To overcome this problem, he proposed a corrector consisting of octupoles and quadrupoles.

Peak-to-peak tracking method for measurement of optical path difference: Revisited

Optik ◽  
2015 ◽  
Vol 126 (24) ◽  
pp. 5420-5422
Author(s):  
H.H. Ley ◽  
A. Yahaya ◽  
Y. Munajat
Keyword(s):  
Optical Path Difference ◽  
Path Difference ◽  
Optical Path ◽  
Tracking Method ◽  
Peak Tracking

Optical T-Bench Method for Measurement of Optical Path Difference

1963 ◽  
Vol 1 (6) ◽  
Author(s):  
Francis E. Washer ◽  
Walter R. Darling
Keyword(s):  
Optical Path Difference ◽  
Path Difference ◽  
Optical Path

Thermo-Fluid Design Simulation of Nd3+ POCl3 Transverse Flow Liquid Laser Cavity

2021 ◽  
pp. 1-31
Author(s):  
Vinod Singh ◽  
Gaurav Singhal ◽  
Prabal Talukdar
Keyword(s):  
Refractive Index ◽  
Temperature Gradient ◽  
Flow Rate ◽  
Optical Pumping ◽  
Gain Medium ◽  
Optical Path Difference ◽  
Path Difference ◽  
Transverse Flow ◽  
Optical Path ◽  
Liquid Laser

Abstract CFD based thermal design of a transverse flow optical cavity is carried out for 1 kW Nd3+ POCl3 liquid laser source to investigate temperature and velocity distribution in the optical pumping region of the cavity. Temperature gradient and turbulence both affect the refractive index of the liquid gain medium, which results in optical path difference, divergence and hence, poorer quality of the laser beam. The main purpose of this design is to achieve uniform flow and least temperature gradient in the optical pumping region so that the optical path difference can be minimized and a good beam quality can be achieved. CFD model has been developed for carrying out thermo-fluid simulations for this thermal system and based on these simulations, an optimum geometry of inlet ports along with their position from optical pumping region have been proposed. A user defined function (UDF) is incorporated for the input of spatially varying heat source term in each cell of the optical pumping region of the cavity. Variations in refractive index and optical path difference are estimated from the temperature data using another UDF. Simulation reveals that mass flow rate between 1.5 kg/s to 2.0 kg/s maintains the optical homogeneity of gain medium. Preliminary experiments have been carried out to demonstrate the effect of flow rate on the beam divergence and thereby exhibiting the importance of present simulation work.

Thermal optical path difference analysis of off-axis lens ray trace foot-print at Cassegrain telescope correct lens assembly

2012 ◽  
Author(s):  
Ming-Ying Hsu ◽  
Yu-Chuan Lin ◽  
Chia-Yen Chan ◽  
Wei-Cheng Lin ◽  
Shenq-Tsong Chan ◽  
...  
Keyword(s):  
Optical Path Difference ◽  
Path Difference ◽  
Optical Path ◽  
Difference Analysis ◽  
Lens Assembly ◽  
Ray Trace ◽  
Cassegrain Telescope

scholarly journals Real-time optical path difference compensation at the Plateau de Calern I2T interferometer

2001 ◽  
Vol 365 (2) ◽  
pp. 301-313 ◽  
Author(s):  
B. Sorrente ◽  
F. Cassaing ◽  
G. Rousset ◽  
S. RobbeDubois ◽  
Y. Rabbia
Keyword(s):  
Real Time ◽  
Optical Path Difference ◽  
Path Difference ◽  
Optical Path
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