Winlens lab instructions

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From Fig. 7, you can get an idea of what the curvature of the image plane is for a disposable camera.
This camera has no mechanism for adjusting the focus, so we choose 4 m as fixed focus distance. Let WinLens use three points for its calculations: the axis, the long side of the negative (r=18 mm) and a third point in between. A planar object normal to the optical axis, imaged by a simple lens, will be imaged as a plane only approximately. The image field is actually curved. To compensate for this curvature, we will bend the film. Let the curvature of the image plane be spherical, and only consider the meridional plane, ignoring that the film in practice only can be cylindrically bent. The radius of curvature of the film (i.e., of the image field) cannot be arbitrarily small, so you have to choose parameters that give you a reasonable field curvature. See the hint on field curvature below. Analyse the spot diagrams and try to optimize the spot-sizes. Don’t forget to consider the off-axis points. Analyse the MTF. The 24x36 mm 2 negatives are usually enlarged to 10x15 cm 2 paper copies, i.e. approximately 4 times. When observing paper copies the perceived sharpness is correlated to the MTF of the image at approximately 2 cycles/mm. Therefore, optimize the MTF for the spatial frequency 7.5 cyc/mm in the image plane. To analyse the depth of focus of your camera, investigate its performance at object distances ∞ and 1 m. At 1 m, the camera is defocused and you have to use defocus to achieve good imaging. Report your considerations and results, specifically the values you choose for the six design parameters. Make sure to report all relevant data. (You can, for instance, report your parameter values in form of a screen printout or snapshot as in Fig. 8) Hint about field curvature Neglecting astigmatism, the displacement Δx of an image point from the paraxial image plane is given by (the Petzval curvature) ∆x = y! 2 ! R ! 1 n ! ′ − 1 n ! , where y is the height in the image plane, Ri is the radius of curvature of the i:th surface, and ni and ni’ are the refractive indices in front of and behind the i:th surface, respectively. For a simple meniscus lens as those in the disposable cameras, ∆x = y! 2 R ! − R ! 1 − 1 n ! ,
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 and 14: diffraction-limited system 13 with
Page 15 and 16: the chief ray originating in the sa
Page 17 and 18: Compare and discuss the imaging per
Page 19 and 20: a. Choose (on the Conjugates tab) F
Page 23: To make it easier to compare differ

Winlens lab instructions

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