Equidistant Lines Research Articles

Measuring the wavelength of light with a self-calibrating grating

A novel scheme for making absolute wavelength measurements with a grating spectrograph is proposed. A grating with special multiple rulings is illuminated with a reference laser of known wavelength to project a ruler-like diffraction pattern of equidistant wavelength calibration lines directly onto the unknown spectrum.

Simultaneous detection of a mass spectrum using a channeltron electron multiplier array

A simultaneous ion detector is described, consisting of a channeltron electron multiplier array with phosphor screen and a vidicon—multichannel analyser combination. Conversion factors and resolutions of the different components were measured. The detector system allows 100 equidistant ion line images to be resolved at 10% valley definition. Ion currents of minimally 3 · 10 −16 A could be monitored directly at the cathode ray tube (CRT) screen; the minimum number of ions necessary to produce a detectable peak is approximately 220. Spectra of krypton and xenon, obtained with a single focussing magnetic instrument, show a maximum ratio of simultaneously detectable masses of 1.16 and a 2% peak amplitude accuracy. Potentially, the new detector could fine wide application in the analysis of minute sample quantities, in the recording of extremely short lasting ion events and in the alignment or focussing improvement of ion optical apparatus.

Le decouverte de civilisations anciennes a l'aide de la photogrammetrie (Discoveries on ancient civilisations through the use of photogrammetry)

Subject of the present study is the ancient town of Nicopolis, which was built in Epirus (Greece) by the Roman Emperor Octavius to commemorate the great victory which he won at the naval battle of Actium (31 B.C.), in which he defeated his adversaries General Marc Antony, and Cleopatra, the Queen of Egypt. The aerial photographs used for this study reveal the existence of a Roman cadastral in the area of Nicopolis and permit us to determine its location, the area it covered and its form. These photographs clearly prove the existence of a Roman cadastral divided by clusters of parallel and equidistant lines which intersect at right angles. The forms determined by these lines on the ground are square, the sides being about 710 m (ca. 777 yards), which is a characteristic element of the Roman cadastral. The study is supplemented by some remarks on the precision of the alignment of this cadastral.

Etude d'un épandage aérien d'urée en forêt

In September 1973, an aerial spraying of 336 kg/ha of urea was made over an area of 34 ha covered by firs 20–70 years old. Within the 35 permanent sample plots each comprising 0.04 ha and established at random on equidistant lines every 100 m, open cans had been placed one week before the spraying. They were taken 2 weeks after the end of the spraying and after checking that the urea intercepted by the trees had fallen. An average quantity of urea equivalent to 347 kg/ha was collected. Approximately 29% of the area received 336 ± 56 kg/ha of urea, 37% received less, and 34% received more. Five cylindrical cans having a diameter of 23 cm and a height of 24 cm in each of the 10 plots were sufficient to determine the exact rate of spraying, but at least 35 plots were necessary to know the distribution of urea in such an area. However, 10 cans were necessary to determine with sufficient accuracy the quantity of urea sprayed on each plot.

On the magnetic properties of dislocations in silicon

The anisotropy of a group of equidistant lines in the EPR spectrum of plastically deformed Si can be described as line splitting in a nearly axial crystal field, the axis being parallel to the Burgers vector of the dislocations. We suppose that the spins of the unpaired electrons in the core of the 60° dislocations are coupled along limited segments giving rise to superparamagnetic resonance.

A Vertical Horopter

When a perpendicularly stretched thread is fixated at its centre with the eyes in symmetrical convergence, the thread has to be tilted around the fixated point with its top away from the observer for it to appear perpendicular. This fact was recognized by a number of investigators as early as the 1850's. For this reason both Hering and Helmholtz described the horopter as an ‘upside-down’ cone. The present investigation employs a twin point-light source apparatus to estimate the orientation and the shape of a subjective equidistant line that lies in the median plane of the observer. Since the method of measurement depends on retinal disparity clues, this locus corresponds to the stereoscopic frame of reference in the median plane. The results are in qualitative agreement with previous findings. Quantitatively, however, they show a much smaller tilt of the reference plane than the ones reported by Helmholtz and others. The stereoscopic sensitivities of the retinal regions at the various elevations above and...

Luminescence of secondary uranium minerals at low temperatures

ABS>The following classes of uranium minerals and their synthetic analogues have been studied: a) phosphates and arsenates, b) silicates. c) carbonates and sulfate-carbonates, d) sulfates, e) vanadates, f) molybdates and g) hydroxides. Their spectra of luminescence (SL) at 77 and 298 deg K have been determined. At 298 deg K the minerals of classes e to g are not luminescent. In all SL, at 77 deg K. there are observed equidistant lines of symmetric vibration of uranyl, and for uranium micas often also lines of antisymmetric vibration. The role of specific forms of water participating in various uranium aqua-centers of luminescence in autunites has been investigated. Minerals manifcsting bright luminescence at 298 deg K are characterized by a vibrational constant between 800 and 840 cm/sup -1/. Its value decreases to 700 to 770 cm/sup -1 for minerals having no luminescence at 298 deg K (classes e to g) and those having only faint luminescence (classes b and d). The SL at 77 deg K assures fast and reliable identification of minerals in most cases. (tr-auth)

EPR of Pb + ions and exchange-coupled Pb + ion pairs in U.V.-irradiated PbCl 2 and PbBr 2 crystals

In PbCl 2 and PbBr 2 single crystals at low temperatures (< 200 K) three types of paramagnetic centres (to be called A, B and C) can be created by u.v. irradiation. The A signal in PbCl 2 consists of five equidistant (35 G) gaussian-shaped lines with a width of 15 G. The experimental g-value of the central component is 2.0665−0.0310 cos 2 θ with θ the angle in the ab plane. The A signal is ascribed to Pb +-type centres at Pb ++ lattice sites. These centres may occur isolated as well as in exchange-coupled pairs along the a axis. The positive shift of the experimental g-values is ascribed to covalent admixtures of excited charge-transfer configurations to the Pb + (6p) ground state. The unusual behaviour of the A-signal intensity as a function of time and irradiation history is explained by a model in which photoelectrons are trapped at dislocations, from which they subsequently are released by a one-phonon interaction, migrate through the lattice and are trapped at Pb ++ ions near trapped holes. The lifetime at 77 K of an electron at a dislocation trap level with depth E is approximately given by (4−0.6 E/kT) -1 10 3 s for 0< E/kT<6. The exchange coupling of the Pb + pair is shown to be isotropic and antiferromagnetic with J =(16.7 ± 2.1) cm -1. The B signal ( g=2.0024) is probably due to colloidal lead particles. The C signal in PbCl 2 ( g=2.064−0.008 cos 2 θ, width 72 G at 10 K) is only found at temperatures <50 K and is ascribed to trapped holes. In PbBr 2 only weak A- and B-type signals are found. The exchange coupling of the Pb + pairs in PbBr 2 is slightly anisotropic.

Piezoelectric Lines in Rochelle Salt Crystals

Sharp piezoelectric lines from plates of Rochelle salt crystals, composed of a series of equidistant lines, have been quantitatively studied. By the use of a probe, these lines have been confirmed to be excited at certain spots on a crystal. The frequencies of piezoelectric lines from a -, b - or c -plates are inversely proportional to thickness d , and well described by f =1/2( p / d )( c 55 /ρ) 1/2 or f =1/2( p / d )( c 66 /ρ) 1/2 , which are frequencies of the thickness-shear vibration. The elastic stiffnesses c 55 and c 66 have been obtained as a function of temperature, by the measurements of frequencies of priezoelectric lines.

Holographic generation of depth contours using a flash-lamp-pumped dye laser

This paper describes holographic contour generation by using a multiple-frequency flash-lamp-pumped dye laser, which was operated in the TEM 00 mode. The emission spectrum was confined to 5 equidistant lines separated by 1.4 nm. As a result, depth contours of high definition appeared on the object, their separation corresponding to a depth difference of 0.12 mm.

Approximate representations of absorption functions of elasser and statistical models of bands

The determinat ion of t r ansmiss ion functions on the basis of distinct model representa t ions is of great significance in the problem of t r ansmiss ion of infrared emiss ion through the a tmosphere . The s imples t model of a group of spec t ra l l ines is the E l sas se r model of equidistant lines of identical intensity. According to that model, the average absorpt ion A t in a given spectra l interval in the weak-l ine approximation (u << 1) is given by

A scanning, recording and integrating microinterferometer.

The instrument is primarily intended for the determination of dry weight of biological objects through measurement of the optical path difference (o.p.d.). This is accomplished with the aid of a shearing interference microscope and a servo driven analyzer. The specimen is placed on a precision scanning stage capable of moving in two perpendicular directions. The scanning is performed in a pattern consisting of equidistant parallel lines covering the whole object. During scanning a recorder pen draws momentary o.p.d. values on a chart that moves synchronously with the specimen, thus giving “cross sections” of the object. The area below this curve is continuously measured and recorded by an integrator, thereby giving data that are easily calculated into total dry weight values.

Nuclear magnetic resonance of holmium in a ferromagnetic alloy

We have observed spin echoes at microwave frequencies in a ferromagnetic alloy of holmium and gadolinium. Seven approximately equidistant lines have been detected at frequencies which are in good agreement with the hyperfine parameters calculated by Bleaney for 165Ho.

Flexural vibrations of plates by the moire method

The reflected image moire method was used to yield the vibration modes of plates. Interference of the reflection of a reference grating from the specularly polished surface of a vibrating plate with a second similar grating created a moire pattern consisting of straight equidistant lines corresponding to the nodal regions of the plate. The moire pattern produced when the plate was illuminated by a continuous parallel light beam yielded the nodal configuration of the vibrating plate. When the vibrating plate was illuminated by a stroboscopic light source the moire pattern showed the contour map of partial slopes of the plate at the instant of illumination. While the first technique, with continuous illumination, yielded the exact form and location of the nodes and antinodes of a vibrating plate at its natural frequencies, the second technique, with intermittent light, gave the local amplitude and phase distribution of the plate.

プラステシンを用いた鋼の熱間孔型圧延の変形過程に関する研究

Three typical passes i. e. square-oval pass, square-dia. pass and box-pass for caliber rolling were designed which had concave-, convex-and normal shapes of projected contact surface respectively. Model billetsbuiltup of alternate layers of gray and white plasticine were prepared and part-rolled between smooth plastercast rolls using CaCO3 powder as lubricant whose condition was well known to give a good simulationof hot rolling of steel and the deformation patterns were analyzed so as to reveal the deformation processof caliber rolling.The results were as follows:(1) The deformations of equidistant lines perpendicular to the direction of rolling on the billet surfaceare characterized by the shape of contact surface, i. e. in square-oval pass of concave-shaped contact surfacethe lines bend backward. In square-dia. pass of convex-shaped contact surface, however, bending is forwardinstead of backward. There is no bending in box-pass of normal contact surface.(2) The elastic wedge in the material at the entry side shortens its length or eventually vanishes if itslocation is near the middle of billet for square-oval pass or near the edge for square dia. pass. This effectmeans that there is such interaction between the parts of long contact-arc and short one that the deformation of the former facilitates the deformation of the latter. In other words, the deformation of the formeris restrained by the latter.(3) In all cases, adhesion of material to the rolls occurs over a wide area of contact surface except narrowzones near entry and exit.(4) The neutral point for caliber rolling can be determined from normal strain distribution in the directionof rolling because at the neutral point the velocities of roll-surface and the material are equal, thusnormal strains along the arc of contact and along the center line of material must be equal. This point approximatelycoincides with the point of maximum bending of line perpendicular to the direction of rollingin the plane normal to the roll axis. The neutral lines in both caliber rollings except box-pass are slightlybent backward.(5) The normal strain in the direction of spreading along the horizontal center line of the cross-sectionof rolled billet is relatively small and uniform in square-dia. pass. In square-oval pass, however, it isextremely large near the edge and small in the middle.

Recherche d'une Phase Nématique à la Température Ambiante

Abstract A critical review of mesomorphic substances at room temperature is made. Some mesomorphic phases not yet or insufficiently described have been studied in polarizing microscope with heating stage. Mesomorphic phases of tetrahydrate and eicosahydrate of dodecylammonium ethanoate are smectic with focal conic structure. Aqueous solutions of purified soya lecithin are smectic and never nematic. Mesomorphic phases of aqueous solutions of various industrial polyethylene glycol monooleates (molecular weights 200 to 4000) are studied. At room temperature pure materials have particular surface relief. A similar product 2,2′ dihydroxyethyl ether monododecanoate also presents this relief and is mesomorphic at room temperature. Exsicated “teepol” exhibits parallel equidistant lines.

Electron spin resonance in electron-irradiated n-type silicon carbide

The effects of 08 Mev electron irradiation on 6H-type hexagonal silicon carbide doped with nitrogen were studied by electron spin resonance and optical absorption methods. After irradiation the optical absorption peak at 16 400 cm-1 disappeared and in the electron spin resonance spectrum a strong isotropic line with g value 20036 ± 00005 as well as six equidistant lines with separation of about 14 G and g value 20032 ± 00005 were observed at room temperature. These lines are probably due to aluminium impurities. On cooling the specimen down to 77°K it was found that the three-line nitrogen spectrum had disappeared and six pairs of anisotropic lines were observed. These were found to be fine structure lines with spin S = 1, D = 0052 ± 0002 cm-1, g⊥ = 2010 ± 0001 and g|| = 2005 ± 0001. After heating the crystal to 200°C, the six pairs of lines disappeared and the three nitrogen lines were partially restored. Furthermore, two lines with separation of about 18 G were observed at room temperature. These lines are probably due to hyperfine interaction with the 29Si nucleus or with an impurity, e.g. 31P, with nuclear spin I = ½. After repeated heating and annealing of the crystal at higher temperatures, the nitrogen electron spin resonance spectrum was restored, but the line intensities were now sensitive to light of wavelength 11 000 A. A model is put forward to explain these effects.

Some observations on models of absorption spectra

The question of models of absorption spectra as applied to the problems which arise in investigations of the propagation of infrared radiation in the atmosphere is discussed. The general and asymptotic formulas for the absorption function of individual lines, models of equidistant lines of equal intensity and statistical models are considered successively. Certain new formulas are introduced without mathematical derivation. Inaccuracies and errors in the literature are corrected, and the square-toot law is considered critically. The general conclusions resulting from the investigations into spectral models are analyzed.

E.S.R. study of the free radicals produced by the γ-irradiation of pyridine

Pyridine and pyridine-d 5 have been irradiated with gamma rays at 77°K and the E.S.R. spectra have been studied as a function of temperature up to the melting point of the compounds. The spectra show that at least two radicals are present at 77°K. The spectrum observed at that temperature with pyridine consists of a triplet (splitting 30 G) superimposed on a more complex signal. The same triplet is observed with pyridine-d 5 and has been assigned to a radical cation formed by abstraction of an electron from the nitrogen lone pair. As the temperature is raised, the total intensity of the E.S.R. signal decreases and the triplet disappears leaving, in the case of pyridine, a spectrum consisting of eight equidistant lines (splitting 12 G). This spectrum has been assigned to a radical formed by the capture of a hydrogen atom by the nitrogen. It is concluded that the smaller radiochemical stability of pyridine as compared with that of benzene has to be related to the presence of the lone pair electrons of nitrogen.

Gratings for measuring separation of equidistant parallel straight lines

Gratings for measuring separation of equidistant parallel straight lines