Study on the dynamic control of spherical aberration on the stable zone of the first three low-order modes of LD end-pumped lasers

2021 ◽  
Vol 478 ◽  
pp. 126397
Author(s):  
Chi Feng ◽  
Si Chen ◽  
Lin-He Huang ◽  
Yuan Dong ◽  
Guang-Yong Jin
Keyword(s):  
Spherical Aberration ◽  
Dynamic Control ◽  
Stable Zone ◽  
Low Order

Theoretical analysis for spherical aberration induction with low-order correction in refractive surgery: comment

2012 ◽  
Vol 51 (31) ◽  
pp. 7626 ◽  
Author(s):  
Rosario G. Anera ◽  
Aixa Alarcón ◽  
F. Pérez-Ocón ◽  
Jose R. Jiménez
Keyword(s):  
Theoretical Analysis ◽  
Refractive Surgery ◽  
Spherical Aberration ◽  
Order Correction ◽  
Low Order

Precise measurement of third-order spherical aberration using low-order zone-axis Ronchigrams

2006 ◽  
Vol 106 (3) ◽  
pp. 153-163 ◽  
Author(s):  
Takashi Yamazaki ◽  
Yasutoshi Kotaka ◽  
Yoshio Kikuchi ◽  
Kazuto Watanabe
Keyword(s):  
Precise Measurement ◽  
Spherical Aberration ◽  
Zone Axis ◽  
Third Order ◽  
Low Order

scholarly journals Ocular and corneal aberrations changes in controlled randomized clinical trial MiSight® Assessment Study Spain (MASS)

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Daniela Lopes-Ferreira ◽  
Alicia Ruiz-Pomeda ◽  
Belén Peréz-Sanchéz ◽  
António Queirós ◽  
César Villa-Collar
Keyword(s):  
Clinical Trial ◽  
Contact Lenses ◽  
Spherical Aberration ◽  
High Order ◽  
Control Group ◽  
Myopia Progression ◽  
Corneal Aberrations ◽  
Single Vision ◽  
Control Versus ◽  
Low Order

Abstract Background To compare ocular and corneal inherent aberrations in the naked eyes of randomly selected children fitted with MiSight contact lenses (CL) for myopia control, versus children corrected with single-vision spectacles (control), over a 24-months period. Methods Children aged 8 to 12 years, with myopia (-0.75 to -4.00 D sphere) and astigmatism (< -1.00 D cylinder) were randomly assigned to the lens study group (MiSight) or the control group (single-vision spectacles). The root mean square aberration (RMS) was determined as corneal (RMS_C), corneal high order RMS (HO_RMS_C), corneal low order RMS (LO_RMS_C), ocular (total) RMS (RMS_T), ocular high order RMS (HO_RMS_T), ocular low order RMS (LO_RMS_T), corneal spherical aberration (SA_C) and ocular SA (SA_T) were calculated by aberrometry measures at the baseline, on 12-months and 24-months visits. A 5 mm diameter was defined for the analysis in all visits for all subjects. Only the dominant eye was analyzed. Results Seventy-four subjects completed the clinical trial: 41 subjects from the MiSight group (age: 11.01 ± 1.23 years) and 33 from the single-vision group (age: 10.12 ± 1.38 years). RMS_T significantly changed (0.57 ± 0.20 µm, p = 0.029) after 24-months in the control group. In the MiSight group no significant changes were registered (p > 0.05). The SA_C and SA_T did not reveal significant changes between visits or between groups (p > 0.05). Conclusions Along 2 years, MiSight CL did not induce significant changes in RMS of anterior cornea or total ocular RMS. Contrary, in control group the RMS_T significantly changed as response of greater eye growth and myopia progression. The results obtained in present study allow to predict corneal or total aberration changes, in children, in response of wearing of MiSight lens along the time. Trial registration : ClinicalTrials.gov Identifier: NCT01917110.

scholarly journals Ocular and Corneal Aberrations changes in controlled randomized clinical trial MiSight® Assessment Study Spain (MASS)

2020 ◽  
Author(s):  
DANIELA LOPES-FERREIRA ◽  
Alicia Ruiz-Pomeda ◽  
Belén Peréz-Sanchéz ◽  
António Queirós ◽  
César Villa-Collar
Keyword(s):  
Clinical Trial ◽  
Axial Length ◽  
Contact Lenses ◽  
Spherical Aberration ◽  
High Order ◽  
Control Group ◽  
Myopia Progression ◽  
Corneal Aberrations ◽  
Single Vision ◽  
Low Order

Abstract BackgroundTo compare ocular and corneal inherent aberrations in the naked eyes of randomly selected children fitted with MiSight contact lenses (CL) for myopia control, versus children corrected with single-vision spectacles (control), over a 24-months period.MethodsChildren aged 8 to 12 years, with myopia (-0.75 to -4.00 D sphere) and astigmatism (< -1.00 D cylinder), were assigned to the lens study group (MiSight) or the control group (single-vision spectacles). Axial length (AL) was measured by biometry, corneal RMS (RMS_C), corneal high order RMS (HO_RMS_C), corneal low order RMS (LO_RMS_C), ocular total RMS (RMS_T), ocular total high order RMS (HO_RMS_T), ocular total low order RMS (LO_RMS_T), corneal spherical aberration (SA_C) and ocular total SA (SA_T) were calculated by aberrometric measures at the baseline, and on 12- and 24-months visits. A 5 mm diameter was defined for the analysis in all visits for all subjects. Only the dominant eye was analyzed.ResultsSeventy-four subjects completed the clinical trial: 41 subjects from the MiSight group (age: 11.01 ± 1.23 years) and 33 from the single-vision group (age: 10.12 ± 1.38 years). In the control group, axial length changed significantly (0.444 ± 0.049 mm, p < 0.001) after 2 years. Also RMS_T (0.565 ± 0.199 µm, p = 0.029) and LO_RMS_T (0.461 ± 0.175 µm, p = 0.047) registered significant changes after 24-months in the control group. In the MiSight group, only axial length changed significantly (0.284 ± 0.025 mm, p < 0.001) after 2 years. The SA_C and SA_T did not reveal significant changes between visits or between groups.ConclusionsThe wear of MiSight CL did not induce significant changes in aberrations in anterior cornea and contrary of control group the total ocular RMS and low order RMS did not significantly caused by significantly lower eye growth and myopia progression,Trial registration: ClinicalTrials.gov Identifier: NCT01917110.

scholarly journals Ocular and Corneal Aberrations changes in controlled randomized clinical trial MiSight® Assessment Study Spain (MASS)

2020 ◽  
Author(s):  
Daniela Lopes-Ferreira ◽  
Alicia Ruiz-Pomeda ◽  
Belén Peréz-Sanchéz ◽  
António Queirós ◽  
César Villa-Collar
Keyword(s):  
Clinical Trial ◽  
Contact Lenses ◽  
Spherical Aberration ◽  
High Order ◽  
Control Group ◽  
Myopia Progression ◽  
Corneal Aberrations ◽  
Single Vision ◽  
Control Versus ◽  
Low Order

Abstract Background: To compare ocular and corneal inherent aberrations in the naked eyes of randomly selected children fitted with MiSight contact lenses (CL) for myopia control, versus children corrected with single-vision spectacles (control), over a 24-months period. Methods: Children aged 8 to 12 years, with myopia (-0.75 to -4.00 D sphere) and astigmatism (< -1.00 D cylinder), were assigned to the lens study group (MiSight) or the control group (single-vision spectacles). Axial length (AL) was measured by biometry, the root mean square aberration (RMS) was determined as corneal (RMS_C), corneal high order RMS (HO_RMS_C), corneal low order RMS (LO_RMS_C), ocular total RMS (RMS_T), ocular total high order RMS (HO_RMS_T), ocular total low order RMS (LO_RMS_T), corneal spherical aberration (SA_C) and ocular total SA (SA_T) were calculated by aberrometric measures at the baseline, and on 12- and 24-months visits. A 5 mm diameter was defined for the analysis in all visits for all subjects. Only the dominant eye was analyzed. Results: Seventy-four subjects completed the clinical trial: 41 subjects from the MiSight group (age: 11.01 ± 1.23 years) and 33 from the single-vision group (age: 10.12 ± 1.38 years). In the control group, RMS_T (0.57 ± 0.20 µm, p = 0.029) and LO_RMS_T (0.46 ± 0.18 µm, p = 0.047) registered significant changes after 24-months in the control group. In the MiSight group no significant changes were registered. The SA_C and SA_T did not reveal significant changes between visits or between groups. Conclusions: The wear of MiSight CL did not induce significant changes in aberrations in anterior cornea and contrary of control group the total ocular RMS and low order RMS did not significantly caused by significantly lower eye growth and myopia progression. The naked eye results obtained in present study allow to predict that children do not develop basal corneal or total aberration changes in response of wearing MiSight lens along the time.Trial registration: ClinicalTrials.gov Identifier: NCT01917110.

the effects of resonance with Jupiter in the system of short-period comets

1974 ◽  
Vol 22 ◽  
pp. 193-203
Author(s):  
L̆ubor Kresák
Keyword(s):  
Structural Effects ◽  
Order Resonance ◽  
Mean Motion ◽  
Short Period ◽  
The Mean ◽  
Compound Effect ◽  
Low Order

AbstractStructural effects of the resonance with the mean motion of Jupiter on the system of short-period comets are discussed. The distribution of mean motions, determined from sets of consecutive perihelion passages of all known periodic comets, reveals a number of gaps associated with low-order resonance; most pronounced are those corresponding to the simplest commensurabilities of 5/2, 2/1, 5/3, 3/2, 1/1 and 1/2. The formation of the gaps is explained by a compound effect of five possible types of behaviour of the comets set into an approximate resonance, ranging from quick passages through the gap to temporary librations avoiding closer approaches to Jupiter. In addition to the comets of almost asteroidal appearance, librating with small amplitudes around the lower resonance ratios (Marsden, 1970b), there is an interesting group of faint diffuse comets librating in characteristic periods of about 200 years, with large amplitudes of about±8% in μ and almost±180° in σ, around the 2/1 resonance gap. This transient type of motion appears to be nearly as frequent as a circulating motion with period of revolution of less than one half that of Jupiter. The temporary members of this group are characteristic not only by their appearance but also by rather peculiar discovery conditions.

CBED Shadow Images and Cs:Aberration Measurement

1982 ◽  
Vol 40 ◽  
pp. 696-697
Author(s):  
R. W. Carpenter ◽  
I.Y.T. Chan ◽  
J. M. Cowley
Keyword(s):  
Focal Point ◽  
Spherical Aberration ◽  
Optic Axis ◽  
Wide Angle ◽  
Caustic Surface ◽  
Convergent Beam

Wide-angle convergent beam shadow images(CBSI) exhibit several characteristic distortions resulting from spherical aberration. The most prominent is a circle of infinite magnification resulting from rays having equal values of a forming a cross-over on the optic axis at some distance before reaching the paraxial focal point. This distortion is called the tangential circle of infinite magnification; it can be used to align and stigmate a STEM and to determine Cs for the probe forming lens. A second distortion, the radial circle of infinite magnification, results from a cross-over on the lens caustic surface of rays with differing values of ∝a, also before the paraxial focal point of the lens.

Resolution Attainable With the Present Day STEM

1973 ◽  
Vol 31 ◽  
pp. 230-231 ◽  
Author(s):  
J. S. Wall ◽  
J. P. Langmore ◽  
H. Isaacson ◽  
A. V. Crewe
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Incident Beam ◽  
Scanning Transmission Electron Microscope ◽  
Aperture Size ◽  
Magnetic Lens ◽  
Peak Intensity ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Half Angle

The scanning transmission electron microscope (STEM) constructed by the authors employs a field emission gun and a 1.15 mm focal length magnetic lens to produce a probe on the specimen. The aperture size is chosen to allow one wavelength of spherical aberration at the edge of the objective aperture. Under these conditions the profile of the focused spot is expected to be similar to an Airy intensity distribution with the first zero at the same point but with a peak intensity 80 per cent of that which would be obtained If the lens had no aberration. This condition is attained when the half angle that the incident beam subtends at the specimen, 𝛂 = (4𝛌/Cs)¼

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