VI. Interferometers for the experimental study of optical systems from the point of view of the wave theory

F. Twyman
1918 The London Edinburgh and Dublin Philosophical Magazine and Journal of Science  
The tP-curvo oven for ~=10~ will, therefore, deviate but very little from the central or Cornu-spiral. In other words, the axial intensity-gradient, for appreciable v, will be very small (as compared with the transversal one, dI/dp). Both curves ~ill start from the origin horizontally. The Cornu spiral is initially flat wtfile the /~-curve has the initial curvature B=27r~r/X, and, if a<0, an inflexion point for v=5--6~)~ , i. e., even for l al =50X, very near the origin. With the exception of
more » ... ch details the B-curves deviate but insignificantly from the focal Cornu spiral, and it would therefore be hardly worth the trouble to draw them accurately.
doi:10.1080/14786440108635735 fatcat:kohjpneilbcr3obtqq7qcyg624