摘要:

The types of systems available are briefly mentioned, together with the mechanisms involved in the photochromic changes. The behaviour of the materials under irradiation, both for activation (colouring) and reversal (erasure), the effect of temperature, and reversibility and resolution are discussed. The optimum performance to be expected for an organic system is noted for comparison. Some properties of commercially available films are given and comparisons made with photographic film. Uset which have been made of photochromic materials and future research trends in their development are summarized.

ISSN:0030-3909    

DOI:10.1080/713818150

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

A triangular interferometer is used to produce high contrast fringes for exposing photographic gratings with a spatial frequency variable continuously and linearly from 0 to 43 lines/mm. The effects of wave aberrations are considered and found to be negligible for this particular instrument. An example of its use with a Kodak P.300 plate is shown.

ISSN:0030-3909    

DOI:10.1080/713818152

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Nous nous sommes proposé d'étudier expérimentalement les phénomènes qui prennent naissance lorsqu'une onde électromagnétique frappe un dioptre irrégulier ou périodique. Dans ce dernier cas, il s'agit d'un réseau de diffraction et le problème est de déterminer l'influence de la forme des sillons sur la répartition de l'ènergie diffractée dans les différents ordres. Nous précisons les raisons qui ont motivé une étude dans le domaine des hyperfréquences plutôt que dans celui du spectre visible, puis nous décrivons rapidement les caractéristiques et les avantages du montage utilisé. Les premières mesures faites avec cet appareil ont été celles de l'efficacité de réseaux échelettes et lamellaires en fonction du rapport de la longueur d'onde au pas du réseau, pour les deux directions de polarisation. Les résultats obtenus sont comparés à certains résultats théoriques et à d'autres mesures effectuées dans l'nfrarouge.

ISSN:0030-3909    

DOI:10.1080/713818138

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

A procedure is described which enables three-layer anti-reflection coatings to be designed, which possess zero reflectance at two different wavelengths. There is no simple relationship between the optical thicknesses of the constituent films.

ISSN:0030-3909    

DOI:10.1080/713818145

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713818153

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

A température ordinaire, pour λ = 337 μ, on mesure l'indice ordinaire du quartz: n0= 2,108, et sa biréfringence: ne− n0= 0,048 ± 0,001, qui apparait environ quatre fois plus grande que dans le visible (ne− n0∼ 0,009). Application à la réalisation d'une lame demi-onde pour l'infrarouge lointain (épaisseurx= 3,5 mm), et d'une lame quart d'onde (x= 1,75 mm). La biréfringence ne varie pas avec la température, et le pouvoir rotatoire n'atteint pas trois degrés pour une épaisseur de 25 mm.

ISSN:0030-3909    

DOI:10.1080/713818151

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Luminance change visibility of a Ganzfeld and circular target subtending 15° at the eye was measured for 12 subjects. Visibility of change increased from about 50 per cent at rate of change of 0·03 Log units/sec to 80 per cent at 0·17 Log units/sec. Visibility of change for any one rate and target was identical irrespective of the sign of luminance change. Visibility of luminance change in the Ganzfeld was generally 15 per cent lower than in the 15° target. The luminance change detecting mechanism must therefore depend less upon area signal than on contrast information.

ISSN:0030-3909    

DOI:10.1080/713818154

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Results are presented from an experiment to measure the magnitude of translational head movements during steady fixation when the head was supported in various ways. The significance of the results for eye movement recording is discussed.

ISSN:0030-3909    

DOI:10.1080/713818143

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The distances at which two differently situated coloured targets appear to lie at the same distance from an observer were calculated using a semi-automatic apparatus, which is a modification of Wright's apparatus. The apparatus, when set to work, provides two circular targets of angular subtense of 20 min, seen against a black background. The results of ten observers were statistically analysed, and the analysis supports the view that a red mark situated at the same plane as a blue mark appears nearer. The data can be nearly quantitatively explained on the basis of: (i) Einthoven's theory and the Stiles-Crawford effect, or (ii) chromatic difference of magnification.

ISSN:0030-3909    

DOI:10.1080/713818139

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The angular resolution of imaging systems is defined as the capability of the system to estimate thepositionof a point source object which is observed in a background of gaussian noise. The application of statistical estimation theory gives the resolution in terms of the noise characteristics and the modulation transfer function of the system. The resolution is also considered as the ability to estimate the separation of two point sources. Examples of estimation of both position and source intensity are given for a gaussian-shaped spread function.

ISSN:0030-3909    

DOI:10.1080/713818155

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor