Winlens lab instructions

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Field Aberrations and Transverse Ray Aberrations Field Aberrations To view the field aberrations • click the FLD icon on the Graphs tab of the toolbar. Field Aberrations displays three diagrams: Astigmatism, Distortion and Lat Colour. In each diagram, the horizontal axis represents the aberration, and the vertical axis represents the position in the image field. The highest point on the vertical axis corresponds to the maximum value for the image field (the Image Size Radius on the Field tab of the System Parameter Editor). The Astigmatism is the difference in focus between the meridian and sagittal ray fans. The horizontal axis of the Distortion graph represents the quantity h − h′ h , where h’ is the distance from the optical axis to the chief ray, and h the distance from the optical axis to the paraxial chief ray. The distances, h and h’, are calculated at the image plane. The Lat Colour graph shows the lateral chromatic aberration, i.e. the deviation, calculated in the image plane, of the chief ray due to dispersion. See Fig. 8. The deviation is calculated relative to the chief ray corresponding to the mid wavelength. Transverse Ray Aberrations To view the transverse ray aberration graphs, • click the TRA icon on the Graphs tab of the toolbar. Transverse Ray Aberrations shows the displacement of a non-paraxial ray from
the chief ray originating in the same object point. The displacement is calculated in the image plane. There are two graphs for each object point, one for the sagittal ray and one for the meridional ray. The horizontal axis represents the normalised aperture coordinate. A meridional ray (from an object point below the optical axis) going through the lower edge of the aperture has its aperture coordinate at the leftmost point of the horizontal axis. The vertical scale shows how much higher the ray intersects the image plane, compared to the chief ray. By reason of symmetry, the sagittal ray fan aberrations are the same on either side of the aperture, so only one half is plotted. For further information, see Help (F1). Seidel Aberrations Seidel Abberations (icon SEIDEL ABNS, tab Tables) will only be briefly commented here: For a wavefront to converge to a point, it has to leave the exit pupil as a sphere whose center is the image point, known as the Gaussian reference sphere. In 1856, Ludwig Seidel derived an expression for the difference between the true wave front and the Gaussian reference sphere. (The “true” wavefront in this context is the wavefront as described by third order theory.) He found that the difference can be expressed as a polynomial of five terms, containing different powers of the image field angle, the aperture radius and the azimuth angle of the ray fan. Each of these five terms relate to one of the aberrations: spherical aberration, coma, astigmatism, curvature of field, and distortion. Every surface in an optical system introduces wavefront aberrations. These add up on the way through the system, and the aim of the designer is to make the sum of the aberrations as small as possible. The quantitative relations between the Seidel aberrations and the ray aberrations require a lot of mathematics, but we can use the Seidel Aberrations table to look at the sums for each aberration (in the first row of the table – Totals), and to see the contribution of each surface of the system to the total aberrations. We can, for instance, see how we through “lens bending” (the redistribution of refractive power between the surfaces) can reduce the spherical aberration. See also the help files (“Seidel Aberration Table”, “Seidel Aberrations”, “Wavefront Aberration Polynomial”).
Page 1 and 2: WinLens Lens design and analysis Co
Page 3 and 4: Please note that the teaching assis
Page 5 and 6: The System Parameter Editor has six
Page 7 and 8: Now we need to set parameters for t
Page 9 and 10: Now set the system parameters (obje
Page 11 and 12: the object point at 10 degrees from
Page 13: diffraction-limited system 13 with
Page 17 and 18: Compare and discuss the imaging per
Page 19 and 20: a. Choose (on the Conjugates tab) F
Page 23 and 24: To make it easier to compare differ
Page 25 and 26: This camera has no mechanism for ad

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