Claims
- 1. An illumination system, comprising:
- a light source for producing light;
- a reflector positioned with respect to said light to produce therefrom directed light;
- an optical means having an entrance pupil for receiving said directed light at a characteristic entrance height, an exit pupil for passing the directed light received by said entrance pupil, and an optical axis leading from said exit pupil to an object to be illuminated, said optical means being effective for causing said light passing through said exit pupil to pass therefrom at an exit angle having a tangent which is substantially proportional to the entrance height of said directed light at said entrance pupil, including when said exit angle is larger than 10 degrees; and
- collimation means, having a focal point which is in compliance with a focal point associated with said optical means, disposed between said exit pupil and said object to be illuminated for collimating light arriving at said object, said object to be illuminated being positioned on said optical axis whereby a uniform illumination is obtained on said object with a relatively short optical path of said illumination system.
- 2. An illumination system according to claim 1 wherein said collimation means comprises a Fresnel lens.
- 3. An illumination system according to claim 2, wherein said Fresnel lens comprises a flat incident surface and a grooved exit surface with respect to the optical means.
- 4. An illumination system according to claim 2, wherein said Fresnel lens is constructed to satisfy the formulae: ##EQU18## said Fresnel lens lying on said optical axis and having associated therewith an incident surface, a first locus of points bounding light received at said lens, a second locus of points bounding light passing out of said Fresnel lens, and a grooved surface;
- where f' is the distance, along the optical axis, form the focal point of the optical means to the incident surface of the Fresnel lens; H is a distance from the optical axis to the first locus of point; .theta. is the incident angle at said first locus of points; n is the refractive index of a medium associated with said Fresnel lens; .theta.' is the angle formed by the light entering said Fresnel lens relative to said optical axis; a is the angle formed by the grooved surface relative to the optical axis; R is the distance from the optical axis to the second locus of points; and d is the thickness of said Fresnel lens.
Priority Claims (1)
Number |
Date |
Country |
Kind |
61-138479 |
Jun 1986 |
JPX |
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Parent Case Info
This is a Continuation of Application Ser. No. 07/062,440 filed on June 12, 1987.
US Referenced Citations (11)
Foreign Referenced Citations (5)
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Aug 1983 |
EPX |
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Sep 1987 |
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2939204 |
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Non-Patent Literature Citations (2)
Entry |
Zhdanov and Pankova, "Plastic Fresnel Lenses for Projector Condenser Systems", Optical Technology, vol. 38, No. 2, 2/71, pp. 106-109. |
Halliday and Resnick, Fundamentals of Physics, 1981, pp. 710-713. |
Continuations (1)
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Number |
Date |
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Parent |
062440 |
Jun 1987 |
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