Эротические рассказы

Optical Engineering Science. Stephen RoltЧитать онлайн книгу.

Optical Engineering Science - Stephen Rolt


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spherical refractive surface. If this surface is deemed to comprise ‘the optical system’ in its entirety, then one can use Eq. (1.14) to calculate the location of all Cardinal Points, expressed as a displacement, z along the optical axis. Positive z is to the right and the origin lies at the intersection of the optical axis and the surface. The Cardinal points are listed below. Cardinal points for a spherical refractive surface

images images
images images
Both Principal Points: z = 0
Both Nodal Points: z = R

      In this instance, the two focal lengths, f1 and f2 are different since the object and image spaces are in different media. If we take the first focal length as the distance from the first focal point to the first principal point, then the first focal length is positive. Similarly, the second focal length, the distance from the second principal point to the second focal point, is also positive. The principal points are both located at the surface vertex and the nodal points at the centre of curvature of the sphere. It is important to note that, in this instance, the principal and nodal points do not coincide. Again, this is because the refractive indices of object and image space differ.

      1.4.4 Refraction at Two Spherical Surfaces (Lenses)

Geometrical illustration of refraction by two spherical lens. equation

      Of course, the final angle, φ, can be calculated from φ1 by another application of Eq. (1.14):

equation

      Substituting for φ1 we get:

images images
images images
Both Principal Points: At centre of lens
Both Nodal Points: At centre of lens

      Since both object and image spaces are in the same media, then both focal lengths are equal and the principal and nodal points are co-located. One can take the above expressions for focal length and cast it in a more conventional form as a single focal length, f. This gives the so-called Lensmaker's Equation, where it is assumed that the surrounding medium (air) has a refractive index of one (i.e. n1 = 1) and we substitute n for n2.

      (1.16)equation

      1.4.5 Reflection by a Plane Surface

Geometrical illustration of the process of reflection at a plane surface.
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