50 Years Ago

'Interferometric Raman spectroscopy using infra-red excitation' — Many pure substances and industrial intermediates are strongly coloured and their Raman spectra cannot be recorded using ultra-violet and visible lines, but nearly all compounds have a region of transparency in the near infra-red ... Our sample tube used with the laser [has] plain glass windows at each end so that the exciting radiation passes through the sample and directly into the interferometer. The laser is pulsed and the photomultiplier voltage pulses are 'gated' to remove the noise between pulses. The output is recorded digitally ... and spectra are obtained by Fourier transformation in a digital computer ... Using this apparatus we have observed the Raman spectrum of iodine dissolved in carbon tetrachloride at a molar ratio of 1:1,000 ... The possibilities of Raman measurements with near infra-red exciting lines have thus been demonstrated.

From Nature 5 September 1964

100 Years Ago

'The type-reading optophone' — Any instrument designed for translating optical into acoustic effects, or light into sound, and thus to some extent substituting the ear for the eye, may be appropriately termed an “optophone” ... The latest of these ... is designed with the object of enabling blind persons to “read” ordinary letterpress by means of the ear ... An optical system throws the image of a glowing Nernst filament upon the printed paper, laid face downwards on a suitably perforated desk. This image is broken up into a series of ... luminous dots, flashing with different musical frequencies, by means of a rotating siren disc ... It has been found possible to obtain a “readable” sound from type of the ordinary newspaper size.

From Nature 3 September 1914