Laurence, Lionel · London, School of Optics · leaf 173
, to have no appre-ciable thickness in relation to their focal length, so that the refraction causedby the two surfaces may be presumed to take place at a single refractingplane passing through the optical centre. Further, this plane may be takenas coinciding with the surfaces, and therefore all… … E 1 Et \ AB /I / Fig. 172. Fig. 173. Let Fig. 172 represent a thick bi-Cx. lens of which X and Y are the centresof curvature. From X and Y let any two parallel radii, X B and Y A bedrawn meeting their respective surfaces in B and A; then tangent planesdrawn through A and B are parallel, so that at…
Optics
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