Java程序辅导

8. Simulation of Geometrical Optics
This simulation program is to study the basics of optical lenses and mirrors using ray
diagrams.
Wave motion is easily visualized in terms of successive high points (crests) and low
points (troughs) as a train of circular waves moving radially outward from thesource
in the center. Each of the circular waves represents a wave front. A wave front is
defined here as a locus of points that connect identical wave displacements. A ray
is a line perpendicular to a series of successive wave fronts specifying the direction
of energy flow in the wave. In the study of geometrical optics, it is acceptable to
represent the interaction of light waves with plane and spherical surfaceswith mirrors
and lensesin terms of light rays.
When light is incident on an interface between two transparent optical mediasuch
as between air and glass or between water and glassfour things can happen to the
incident light.
• It can be partly or totally reflected at the interface.
• It can be scattered in random directions at the interface.
• It can be partly transmitted via refraction at the interface and enter the second
medium.
• It can be partly absorbed in either medium.
This Java applet simulates light rays from a source interacting with a surface by
transmission and reflection via ray diagrams.
A principal ray diagram is a graphical method used to locate the image of an object.
Ray tracing follows certain rules. Consider a converging (convex) lens with the object
distance, O, greater than the focal length, , of the lens. To construct the location of
an image, draw the rays as such:
• Any ray that comes into the lens parallel to the axis of the lens will pass through
the focal point on the other side of the lens.
• Any ray that passes through the optical center of the lens is undeflected.
Simulation Tasks:
• Use a point “Source” and a converging “Lens” to obtain a parallel beam. Where
should the beam be placed to obtain such a condition?
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• Place an “Object” a distance from a converging ”Lens” and observe the image
formed when the following are adjusted:
– height and position of the object
– focal length of the lens
– type of lens (ie converging to diverging lens)
• Obtain an image with the “Object” in front of a converging “Lens”. Place a
second converging “Lens” behind the image. Adjust the position of this lens
such that the first image moves from the front to the back of the focal point of
the second lens. What happens to the final/second image? Ie describe the size
and position of the final image as a function of the position of the second lens.
(Note: You may have to adjust the size and position of the first object till a better
observation of the rays is obtained.
• Use a diverging lens as the second lens and repeat the above step. What happens
to the final image?
• Use a ”Mirror” in place of the second lens. Describe the final image.
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