Optics and photonics. Test methods for surface imperfections of optical elements

2017 ◽  
Keyword(s):  
Test Methods ◽  
Optical Elements ◽  
Surface Imperfections

Automated discrimination of surface imperfections and adhered particles on customer-specific optical elements

2019 ◽  
Vol 86 (7-8) ◽  
pp. 399-403
Author(s):  
Alexander Schöch ◽  
Patric Perez ◽  
Sabine Linz-Dittrich ◽  
Carlo Bach ◽  
Carsten Ziolek
Keyword(s):  
Quality Control ◽  
Stereo Vision ◽  
Surface Defects ◽  
Automated System ◽  
Dust Particles ◽  
Optical Elements ◽  
Optical Components ◽  
Geometrical Size ◽  
International Standard ◽  
Surface Imperfections

AbstractIn previous work, we proposed an automated system, capable of detecting surface defects (e. g. edge chips, digs, scratches) on optical components as defined in the international standard ISO 10110-7. It objectively discriminates between defect classes and quantifies their geometrical size. During assessment of quality control at multiple manufacturers, the need for a method to discriminate between dust particles and surface imperfections has been identified. This article describes an approach to automatically assess dust particles and imperfections on the surface of interest based on the stereo vision approach.

scholarly journals Automated surface inspection of small customer-specific optical elements

2017 ◽  
Vol 84 (7-8) ◽  
Author(s):  
Alexander Schöch ◽  
Patric Perez ◽  
Sabine Linz-Dittrich ◽  
Carlo Bach ◽  
Carsten Ziolek
Keyword(s):  
Optical Element ◽  
Light Sources ◽  
Bidirectional Reflectance ◽  
Optical Elements ◽  
Inspection Method ◽  
Manual Inspection ◽  
Surface Imperfections ◽  
Inspection Process ◽  
Bidirectional Reflectance Distribution ◽  
Good Agreement

AbstractIn industry, manual visual inspection is typically applied to assess surface imperfections on basic optical elements according to the standard DIN ISO 14997. This article proposes a machine vision setup to mimic the human tester's inspection process. It consists of multiple cameras and LED light sources. Both are arranged on the surface of a hemisphere with the optical element to be inspected at its center. By enabling individual LED sources on the hemisphere, any movement during acquisition can be omitted. Thus, the system is capable of acquiring a sparse pseudo BRDF (Bidirectional Reflectance Distribution Function) representation of imperfections. It is shown by experiments that this representation allows to discriminate between certain imperfections. Besides the mechanical setup, the image processing methodology and classification results are discussed. A comparison to results from manual inspection for 20 optical elements of the same geometry is also presented. Results indicate that a good agreement with the de-facto standard manual inspection method from industry can be obtained by the system.

Near-field scanning optical microscopy

1986 ◽  
Vol 44 ◽  
pp. 642-643
Author(s):  
E. Betzig ◽  
A. Harootunian ◽  
M. Isaacson ◽  
A. Lewis
Keyword(s):  
Near Field ◽  
Optical Microscope ◽  
Visible Radiation ◽  
Field Methods ◽  
Optical Elements ◽  
Optical Region ◽  
Order Of Magnitude ◽  
Nondestructive Imaging ◽  
Scanning Optical Microscopy ◽  
Near Field Scanning

In general, conventional methods of optical imaging are limited in spatial resolution by either the wavelength of the radiation used or by the aberrations of the optical elements. This is true whether one uses a scanning probe or a fixed beam method. The reason for the wavelength limit of resolution is due to the far field methods of producing or detecting the radiation. If one resorts to restricting our probes to the near field optical region, then the possibility exists of obtaining spatial resolutions more than an order of magnitude smaller than the optical wavelength of the radiation used. In this paper, we will describe the principles underlying such "near field" imaging and present some preliminary results from a near field scanning optical microscope (NS0M) that uses visible radiation and is capable of resolutions comparable to an SEM. The advantage of such a technique is the possibility of completely nondestructive imaging in air at spatial resolutions of about 50nm.

Characterization of Rh/Si multilayer structure by HREM and HAADF

1992 ◽  
Vol 50 (1) ◽  
pp. 122-123
Author(s):  
Y. Cheng ◽  
J. Liu ◽  
M.B. Stearns ◽  
D.G. Steams
Keyword(s):  
Normal Incidence ◽  
High Resolution Electron Microscopy ◽  
X Rays ◽  
Beam Direction ◽  
Cross Sectional ◽  
Optical Elements ◽  
Resolution Electron ◽  
Point To Point ◽  
Better Than

The Rh/Si multilayer (ML) thin films are promising optical elements for soft x-rays since they have a calculated normal incidence reflectivity of ∼60% at a x-ray wavelength of ∼13 nm. However, a reflectivity of only 28% has been attained to date for ML fabricated by dc magnetron sputtering. In order to determine the cause of this degraded reflectivity the microstructure of this ML was examined on cross-sectional specimens with two high-resolution electron microscopy (HREM and HAADF) techniques.Cross-sectional specimens were made from an as-prepared ML sample and from the same ML annealed at 298 °C for 1 and 100 hours. The specimens were imaged using a JEM-4000EX TEM operating at 400 kV with a point-to-point resolution of better than 0.17 nm. The specimens were viewed along Si [110] projection of the substrate, with the (001) Si surface plane parallel to the beam direction.

Laboratory proficiency in susceptibility testing of Helicobacter pylori using agar dilution and E test methods

2001 ◽  
Vol 120 (5) ◽  
pp. A586-A587
Author(s):  
L BEST ◽  
S JO ◽  
V VANZANTEN ◽  
D HALDANE ◽  
V LOO ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Susceptibility Testing ◽  
Test Methods ◽  
Agar Dilution

Scientific and Standardization Committee Communications Comparison of Test Methods for the Lupus Anticoagulant: International Survey on Lupus Anticoagulants-I (ISLA-1)

1990 ◽  
Vol 64 (03) ◽  
pp. 478-484 ◽  
Author(s):  
Thomas Exner ◽  
Douglas A Triplett ◽  
David A Taberner ◽  
Margaret A Howard ◽  
E Nigel Harris
Keyword(s):  
Lupus Anticoagulant ◽  
Test Methods ◽  
Positive Sample ◽  
Direct Proportion ◽  
Clotting Time ◽  
Preliminary Screening ◽  
Activated Platelets ◽  
Tissue Thromboplastin ◽  
Kaolin Clotting Time ◽  
Induced Defects

SummarySix lyophilized plasma samples were sent to 20 “expert” laboratories for assessment of lupus anticoagulant (LA). Four samples contained pooled LA of graded potency mixed with aged normal plasma. One contained LA plus cephalin phospholipid and one contained a nonspecific venom anticoagulant. Sixteen methods were used overall with some participants using up to 8 methods. Results were scored in regard to the known potencies of LA in the samples and other known induced defects.Activated partial thromboplastin time (APTT) tests used by most participants for preliminary screening were relatively sensitive, but non-specific. Platelet or phospholipid neutralization procedures (PNP) appeared to be sensitive and specific but showed a non-linear response to increased LA content. Kaolin clotting time (KCT) tests showed the most sensitive response to increased LA content but the weaker LA were not scored as abnormal by most laboratories as the samples may have contained platelet fragments. Other commonly used tests such as the tissue thromboplastin inhibition (TTI) test and the dilute Russell’s viper venom test (DRVVT) were carried out somewhat inconsistently. The variability in performance of tests in different laboratories indicates that standardization of methodology is urgently required.Generally it seemed that most clotting tests were “bypassed” by the addition of phospholipid to a known LA-positive sample in apparently direct proportion to their sensitivity. Sample preparation, especially prevention of contamination with activated platelets is a vital preliminary part in the assay of LA.

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