The main purpose of the present paper is to describe what the author believes to be a novel method of investigating the micro-structure of metals, and to give some account of preliminary results obtained by its aid. The method was devised in order to throw further light on the true nature of slip-bands, and the preliminary results relate mainly to this question. The investigation described in this paper is thus a further development of researches carried out in the first place by Professor J. A. Ewing, F. R. S. and the author jointly (“The Crystalline Structure of Metals,” Bakerian Lecture, 1899), and subsequently by the present author alone (“The Plastic Yielding of Iron and Steel.”) In the course of correspondence on the latter paper, M. F. Osmond drew the attention of the author to certain experimental facts concerning the behaviour of slip-bands under oblique illumination, which had formerly escaped attention.
Designing a Freeform Optic for Oblique Illumination