The London, Edinburgh and Dublin philosophical magazine and journal of science . to a focus at x, the focus for parallel rays. Here it forms anAirys spurious disk, or rather a somewhat more diffusespurious disk, since the objective falls short of being aplanaticin its treatment of beams of parallel light incident on itsfront surface. Past the focus x the beam advances, anddiverges as it advances. Let D be where the axial ray, thedark line of the figure, intersects the optic axis of the micro-scope. Note that the axial rays of all the other beams emittedfrom the image C will, like this one, sta
The London, Edinburgh and Dublin philosophical magazine and journal of science . to a focus at x, the focus for parallel rays. Here it forms anAirys spurious disk, or rather a somewhat more diffusespurious disk, since the objective falls short of being aplanaticin its treatment of beams of parallel light incident on itsfront surface. Past the focus x the beam advances, anddiverges as it advances. Let D be where the axial ray, thedark line of the figure, intersects the optic axis of the micro-scope. Note that the axial rays of all the other beams emittedfrom the image C will, like this one, start from the pointwhere C is pierced by the optic axis of the microscope, andwill all intersect that axis again at D. At D an image ofC is formed on a somewhat curved surface that stands atright angles to the optic axis of the microscope. Ourbeam, diverging from x, when it reaches this surface con-tributes its quota towards the formation of the image upon passing image D the divergent beam continues tillit reaches the front of the eyepiece. It proceeds through Fig. the eyepiece and is by it brought to a second focus at y,where the eyepiece can form an image of x. If we producethe portion qy of the axial ray backwards, it will intersectthe optic axis at E, where the backward production of theconvergent beam qy will widen out so as to extend overthe space occupied by the virtual image E, and contributeits share towards the formation of that image. Accordinglythe light of our beam, which advances in the direction qy,will enter the eye (the pupil of which should be broughtclose toy) in the same state as if it had come direct from thewhole extent of an image at E. After passing y the beamagain diverges, and by the optical action of the front half of 434 Dr. Gr. J. Stoney on Microscopic Vision. the eye this divergence is lessened and at the same time theaxial ray is bent in so as a third time to intersect the opticaxis of the microscope, where that axis prolonged pierces
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Keywords: ., bookcentury1800, bookdecade1840, bookidlondon, booksubjectscience
