Raw optical glass. Determination of birefringence

1995 ◽  
Keyword(s):  
Optical Glass

The Determination of Parts per Million Levels of Thorium in Optical Components by X-ray Fluorescence

1975 ◽  
Vol 29 (1) ◽  
pp. 63-67
Author(s):  
Joseph A. Keenan
Keyword(s):  
Coefficient Of Variation ◽  
Optical Glass ◽  
Coupled System ◽  
Optical Coatings ◽  
Sample Analysis ◽  
Nondestructive Technique ◽  
Optical Components ◽  
X Ray ◽  
Qualitative Determination

A nondestructive technique for the determination of thorium in optical glass has been devised using tube-excited x-ray fluorescence with an energy-dispersive detector. Capability for full calibration and sample analysis has been incorporated into a computer-coupled system. Bulk thorium concentrations as low as 87 ppm have been detected with a coefficient of variation of 27.2% at 95% confidence using NBS-certified standards. At 466 ppm the coefficient of variation was 5.6% at the 95% confidence level. Qualitative determination of thorium in optical coatings has been demonstrated also.

scholarly journals Automation of Dosimetric Control for Laser Radiation

2018 ◽  
pp. 28-35
Author(s):  
P. Neyezhmakov ◽  
E. Tymofeiev ◽  
О. Lyashenko
Keyword(s):  
Laser Radiation ◽  
Optical System ◽  
Optical Glass ◽  
Rapid Determination ◽  
Laser System ◽  
Processing Unit ◽  
Automated Method ◽  
Direct Laser ◽  
Angular Coordinates

The wide application of laser systems and the increase in the values of their energy characteristics, which may hazard to the health of staff and other people in the area of direct and reflected laser radia­tion, necessitates a permanent dosimetric monito­ring in these areas. However, the methods of mea­suring the parameters of laser radiation at a given point in space to determine the degree of radiation safety for the human body, established in the stan­dard DSTU EN 60825-1: 2016, are difficult to implement when using obsolete monitoring equipment. Therefore, the development of an automated method for determining the characteristics of a laser system and the rapid detection and determination of the direction and coordinates of laser radiation is relevant. The proposed method for automated determination of the laser system characteristics differs by applying an additional measurement channel with a photodetector, as in the main channel, and a compensated filter to ensure the difference of the rea­dings in the channels, so that each difference of measured channel values corresponds to the one wavelength value. For the formation of a compensation filter with a constant spectral characteristic in the most demanded wavelength range from 0.4 microns to 1.1 microns are used by known methods of calculation and manufacturing. A combination of optical glass NSNU 13 and SZS-9 with varying thickness as a compensation filter is permitting measure of laser irradia­tion doze for radiation in this range with an error that does not exceed 15%. It is necessary to perform the tasks of quickly finding and estimating the angular coordinates of the laser sources for monitoring the parameters of laser radiation in the working area. Improving the design of the device for detecting and determining the angular coordinates of laser radiation is made by using an optical system that directs laser radiation to a photodetector of radiation and an information processing unit, in front of which a volume matted screen is installed so that the distance from the middle of the optical system to the nearest point of the screen is greater distance of the optical system. The photodetector matrix installed in the optical system focus is used as a photodetector of laser radiation. The application of spherical screens for direct laser radiation and cones for diffused and diffused reflec­ted radiation is proposed for the effective and rapid determination of radiation corners in the working zone. Dosimeters with automated wavelength monitoring and detection and determination of the angular coordinates of laser radiation will facilitate and reduce the cost of conducting dosimetry monitoring.

Adaptive Protocol for Robust Estimates of Coatings Properties by Nanoindentation

2001 ◽  
Vol 695 ◽  
Author(s):  
Nigel M. Jennett ◽  
Andrew J. Bushby
Keyword(s):  
Coating Thickness ◽  
Optical Glass ◽  
Hard Coatings ◽  
Coating Properties ◽  
Soft Or ◽  
Adaptive Protocol ◽  
Wide Range ◽  
Experimental Parameters ◽  
Indentation Response

ABSTRACTThe determination of the elastic modulus and hardness of a wide range of coating systems has been studied recently in the EC project INDICOAT. This paper describes a protocol for determining the coating properties, which has been developed and tested in that project. The procedure contains simple to implement strategies to evaluate the response of the coating and design a suitable series of indentation experiments that enable a reasonable estimation of ‘coating-only’ properties. The protocol directs how the experimental design adapts the experimental parameters to each sample. An adaptive protocol is essential to cope adequately with the different indentation responses. Indentation response depends, for example, on coating thickness and the relative properties of coating and substrate and creep response. The protocol also has to adapt itself so that it can reliably target the range of indentation depth with respect to the coating thickness necessary to obtain the coating properties from the composite indentation response. Results presented show that the parameters and approach for measurement of hard coatings are very different to those required for soft or ductile coatings. The systems studied are DLC on tool steel, Au on Ni, aluminium oxide on Ni and aluminium on optical glass (BK7).

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

International determination of the total motion of the pole

1961 ◽  
Vol 13 ◽  
pp. 29-41
Author(s):  
Wm. Markowitz
Keyword(s):  
Secular Motion ◽  
The Future

A symposium on the future of the International Latitude Service (I. L. S.) is to be held in Helsinki in July 1960. My report for the symposium consists of two parts. Part I, denoded (Mk I) was published [1] earlier in 1960 under the title “Latitude and Longitude, and the Secular Motion of the Pole”. Part II is the present paper, denoded (Mk II).

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

Sign in / Sign up

Export Citation Format

Share Document