PURPOSE: To show the effect of a gravitational lens.
DESCRIPTION: A lens that is shaped like the stem of a wine glass bends light rays from a small lamp to form the shape of an Einstein Ring. The image is distorted like the static (Schwarzschild) gravitational field of a star. This simulates the optical distortions caused by a Macho object or a non rotating black hole.
A gravitational lens simulator is a lens that is shaped like of the stem of a
wineglass: 
Another view of the lens in its holder: 
The lens it will distort the image of a small light bulb into the image of a ring as shown in the photo at the top of this page. This effect is similar to the gravitational lensing effect of light rays that are bent by a massive, dark object coming between the observer's view and a star.
EQUIPMENT: Gravitational lens, camera, 6 volt truck lamp, power supply.
SETUP NOTES: Use a long, 6 foot rolling table. At one end of the table clamp the 6 volt truck lamp to a holder and connect it to the low voltage DC power supply and set the power supply to 6 volts. In the middle of the table place the gravitational into a holder and clamp the holder to a base.
The general idea in this demo is to use a truck lamp as a 'star' and a video camera as an observers eye. This arrangement is arranged to simulate a star gazer observing a point-like distant star. The gravitational lens is then moved into position between the 'star', that is the truck lamp, and the video camera, that is the observers eye. The observed effect is that the point of light will distort and spread to become a ring like object, called an Einstein ring.
With the room lights off a small lamp is
projected through a video camera. Photo: 
The gravitational lens
simulator is imposed between the lamp and the camera. Photo: 
The Physics Teacher, volume 34, number 9, page 555, December 1996"Simple Gravitational Lens Demonstrations".
Am. J. Phys., Vol. 48, No. 10, October 1980 Pages 883 - 886
Construction of a gravitational lens
Am. J. Phys., Vol. 49, No. 7, July 1981 Pages 652 - 655
Gravitational lens
J. Higbie
Department of Physics, University of Queensland, Brisbane, Australia 4067
A plastic lens is described which will bend light rays parallel to the lens axis in the
same way as a static
(Schwarzschild) gravitational field. This allows one to observe the optical distortions
caused by a (nonrotating)
black hole directly. The double-imaging property is discussed with particular application
to the recently
announced double quasar which is suspected to be a gravitational double image of a single
quasar. A detailed
cosmological model calculation is performed in order to place limits on the mass of the
galaxy acting as the lens. It
is seen that if the double quasar is a double image and if the lens is a massive galaxy
then we will have established
that the quasar redshift is cosmological rather than gravitational. The gravitational lens
thus occupies a key role in
resolving this question.
Am. J. Phys., Vol. 63, No. 6, June 1995 Pages 536-541
Gravitational lenses and plastic simulators
Ronald J. Adler
William C. Barber
Mark E. Redar
San Francisco State University, San Francisco, California 94132
(Received 28 March 1994; accepted for publication 11 November 1994)
The deflection of light by a gravitational field is an important prediction of general
relativity. It is thus an
interesting problem to illustrate the deflection by simulating the appearance of
astronomical objects as seen through
a gravitational field. To do this we have constructed plastic lenses to simulate the
gravitational deflection of light
for three cases: a point mass, a sphere of constant density, and an isothermal gas sphere.
In this paper we discuss
the calculation of the deflection for any distribution of mass, the shape of general
simulation lenses, and the
construction of plastic simulation lenses. To illustrate the results we present photos of
a grid, a dark spot, and a
field of stars and galaxies seen through the lenses. The photos clearly display the
distortion of images, Einstein
rings and arcs, and brightness intensification.