Transactions of The Optical Society 

About: Transactions of The Optical Society is an academic journal. The journal publishes majorly in the area(s): Lens (optics) & Interferometry. Over the lifetime, 216 publications have been published receiving 2298 citations.

The C.I.E. colorimetric standards and their use

Abstract: The new international standards, which define a standard observer, three standard illuminants, standard conditions of illuminating and viewing opaque specimens, a standard for evaluating the brightness factor of opaque specimens, and a standard trichromatic system for the expression of colour measurements, are stated and their origin explained. In addition to the numerical tables which are appended to the resolutions setting up these standards, there are given a table specifying the trichromatic coordinates for the standard observer of all spectral colours at wave-length intervals of 1 mμ, tables to facilitate the calculation of the standard coordinates and the brightness factor of a material illuminated by any one of the three standard illuminants from spectrophotometric measurements on the material, and a table giving the coordinates of some stimuli of special importance on the N.P.L. system, the standard system, and another system which occurs in the resolutions. Some new colorimetric terms are proposed, partly to avoid misinterpretation and partly to meet new needs. The theory of colour transformations, and points which arise in the application of the system and in the calibration of instruments, are discussed.

A re-determination of the trichromatic coefficients of the spectral colours

Abstract: Using a new trichromatic colorimeter a series of colour matches through the spectrum has been made by ten observers. The results have been averaged and a mean set of trichromatic coefficients for the spectral colours derived. These results are compared with previous determinations made by Konig and Abney. The variations in the coefficients that have been found amongst the ten observers must, as a consequence of a new method of basing the trichromatic units, be attributed to variations in the process of reception, but their magnitude appears to be of a small order. On the other hand, there are big differences in the amount of the macular pigment in different eyes and probably some variation in its dominant hue. These variations have been investigated by matches on a standard white, results for 36 observers being given in the paper and a mean value determined. This value, combined with the mean spectral coefficients, has been used to compute an average locus for the spectral colours in the colour triangle, with white at the centre. Other points discussed in the paper include the technique of colour matching, the range of intensity over which matches remained valid, and variations of luminosity.

The structure of abraded glass surfaces

Abstract: The physical nature of the processes involved in the workshop operations of cutting and grinding are but little understood, such attention as these operations have received being mainly of an empirical nature. In the present paper some preliminary observations are recorded on the tooling of hard brittle substances where the phenomena may be expected to be simplest. Even here they are sufficiently complex. The primary object is to substitute the conception of a flaw- or fissure-complex for the current view of a hill-and-hollow structure, as characterising a ground surface in brittle materials. Part I. Section I describes observations on the flaws produced in glass by stationary, rolling and sliding spheres, and by glazier's diamonds and wheels. Section II deals with the structure of ground glass surfaces, applying the results of the previous section, and showing the surface to be a fissure-complex. Section III explains the double refraction observed by Twyman near the surface of these pieces of ground glass. Part II. Section I shows the enhanced solubility of ground surfaces in hydrofluoric acid, and suggests a value for the upper limit of the thickness of the flowed, or surfacetension, layer on polished glass. Section II describes the structure of polished surfaces of glass and similar materials as developed by etching, showing that mechanical abrasion is still active during polishing, and also confirming a low value for the thickness of the surface tension film.

A re-determination of the mixture curves of the spectrum

Abstract: The paper describes a method that has been developed for calculating the sensation curves and mixtures curves from an average set of trichromatic coefficients and the standard luminosity curve, without recourse to any further experimental data. A complete table of colour mixture data is given. The practical value of different methods of colorimetry and the most desirable primaries for use as reference standards are briefly discussed.

A trichromatic colorimeter with spectral primaries

Abstract: The paper describes a trichromatic colorimeter that has been specially designed in order to make an accurate re-determination of the locus of the spectral colours in the colour triangle for as many observers as possible. A spectrometer system is used in which two spectra are formed from the same source. From one of these, three portions to act as primaries are reflected back through a lower part of the dispersing system, so that the mixing of the three radiations is effected by neutralising the prismatic dispersion by which the colours were first separated. From the other spectrum the test colour and a desaturating colour are selected and mixed in a similar manner, and the composite beams are then brought into the two halves of a simple bipartite field. In the process of being mixed with the other colours, each spectral colour is filtered by its return passage through the dispersing system and the instrument thus becomes very effective in removing stray light. Another device has enabled the Maxwellian method of observing the field of view to be adopted without the introduction of rotating parts into the system. The intensities of the three primaries are controlled with photometer wedges.