Imax Cinema- Help Sheet

IMAX CINEMA ÐŽV PHYSICS Coursework Visit ÐŽV Help Sheet

Recommended applications of physics:

1. IMAX Projector and lens

The IMAX projector uses a convex lens with the object (the film strip) very close to the focal point. This produces an inverted, real image with a very high magnification. You could draw a ray diagram to illustrate this.

o The image distance (v) from lens to screen is 16.76 m.

o The height of object (ho) is 6.5cm (height of the film strip.

o The height of image (hi) is 16.46m.

o Formulae magnification m = v/u = hi / ho

o Lens equation: 1/u + 1/v = 1/f

Using this data and the formulae, you could get the focal length of the IMAX lens and the power of the lens.

Using the data given and an estimate of the width of the image, you could also calculate the power on every m2 area of the screen.

Other facts:

o The film is fed sideways at 24 images per second and a speed of 360 feet per minute.

o A vacuum sucks the film on to the apparatus to ensure it is at the correct ÐŽ§u.ЎЁ Otherwise, there would be danger of an unfocussed image.

o The projector lamps are rated at 7500W which is very large compared with standard household bulbs e.g. 60W. They produce pure white light containing all the colours of the spectrum based on a xenon discharge tube.

2. IMAX 3D - Read up on polarization before you read this ÐŽV see resources below.

o The IMAX 3D technology uses two projectors projecting the light through polarizing filters which act at 90 degrees to each other.

o The two images are very slightly separated on the screen.

o The movie is viewed through glasses which have two polarizing filters, again with their axes at 90 degrees to each other.

o The net result of all this is that only light from the left hand image is allowed through the right glasses lens, and only light from the right hand image is allowed through the left glasses lens.

o The

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