Wave plate retarder

• US 4,400,062 A
• Filed: 09/11/1979
• Issued: 08/23/1983
• Est. Priority Date: 09/11/1979
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Sugiki, Mikio, Mori, Hiroshi
• Primary Examiner(s): Rosenberger, R. A.
• Application Number:
  US06/074,308
• Time in Patent Office: 1,442 Days
• Field of Search: 350/157, 350/400, 350/403, 350/406, 356/32, 356/33, 356/35, 356/364, 356/365, 356/367
• US Class Current: 359/489.07
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: Y10S 359/90 Methods

Abstract

A wave plate retarder consists of a stacked plurality of doubly refracting or birefringent high molecular films laminated with a predetermined angle between their respective optical axes to establish a desired phase difference during transmission through the films of components of light polarized along orthogonal axes. The predetermined angle may be selected to provide a phase difference of 1/4 or 1/2 wavelength of light to thus produce a composite wave plate retarder which functions as a 1/4 or 1/2 wavelength plate regardless of the phase difference of components of light produced by transmission through a single film.

Claims

1. A method of making a wave plate retarder comprising the steps of:

placing a film of birefringent material having an optical axis with its surface normal to a linearly polarized beam of light;

rotating said film about an axis parallel to said beam of light;

measuring maximum and minimum values of a linearly polarized component of said beam of light after passing through said film during said rotating of the latter;

determining a retardation phase angle from the following relationship;

space="preserve" listing-type="equation">R=1/2(1+cos Γ

)

in which R is the ratio of said minimum value to said maximum value, and Γ

is the retardation phase angle for said film;

forming from said film two sheets having respective optical angles; and

overlapping said two sheets with an angle C between their optical axes which is determined from the following relationship;

space="preserve" listing-type="equation">R.sup.1 =(1/2 cos 2Γ

-2 cos Γ

+3/2) cos.sup.4 C+2(cos Γ

-1) cos.sup.2 C+1

in which R¹ is 1/2 for a 1/4 wave plate retarder or R¹ is 1 for a 1/2 wave plate retarder.

2. The method according to claim 1;

wherein said film is polypropylene which has been uniaxially stretched during the manufacture thereof to define an optical axis parallel to the direction of stretch.