Prism with no detrimental internal reflection

• US 4,634,223 A
• Filed: 06/06/1985
• Issued: 01/06/1987
• Est. Priority Date: 06/06/1984
• Status: Expired due to Term

• Current Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Ishii, Toshio
• Primary Examiner(s): Henry, Jon W.
• Application Number:
  US06/741,823
• Time in Patent Office: 579 Days
• Field of Search: 350/276 R, 350/276 SL, 350/286, 350/287, 350/167, 350/321, 350/319
• US Class Current: 359/613
• CPC Class Codes: G02B 5/04 Prisms

Abstract

A prism partly of a solid glass block enclosed with inoperative planes is provided on the inoperative planes with transparent members each of which comprises a light transmission part and a light attenuation part having a great number of either superfine prismatic protuberances or small acute indentations formed over the whole outer surface thereof. The transparent member has a refractive index of n₁ which satisfies the following condition:

n.sub.1 ≧n.sub.0 -0.03

wherein n₀ is the refractive index of the prism. A ray of light incident upon the polished surface of the inoperative plane at an angle less than a critical angle passes the through transmission part and then is gradually attenuated as it is repeatedly reflected by the internal surfaces of the prismatic protuberance.

Claims

1. A transparent prism enclosed by operative planes and inoperative planes, said prism comprising:

a solid block forming said prism and having a refractive index of n₀ ; and

transparent members having a refractive index of n₁ which are cemented to said inoperative planes;

each of said transparent members having a light attenuation part on its outer side and satisfying the following condition;

space="preserve" listing-type="equation">n.sub.1 ≧

n.sub.0 -0.03,

said light attenuation part having a great number of either superfine prismatic protuberances or fine acute indentations formed over the whole outer surface thereof, said outer surface being made flat by being coated with a light opaque material.

2. A prism as defined in claim 1, in which said transparent member is integrally molded.

3. A transparent prism enclosed by operative planes and inoperative planes, said prism comprising:

a solid block forming said prism;

transparent members having a higher index of refraction than said solid block, said transparent members being cemented to said inoperative planes;

each of said transparent members having a light attenuation part on its outer side.

4. A transparent prism enclosed by operative planes and inoperative planes, said prism comprising:

a solid block forming said prism and having a refractive index of n₀ ; and

transparent members having a refractive index of n₁ which are cemented to said inoperative planes;

each of said transparent members having a light attenuation part on its outer side and satisfying the following condition;

space="preserve" listing-type="equation">n.sub.1 ≧

n.sub.0 -0.03,

said solid block being glass and said transparent members being acrylic resin.