Optical: systems and elements – Polarization without modulation – By relatively adjustable superimposed or in series polarizers
Reexamination Certificate
2001-03-13
2002-02-19
Shafer, Ricky D. (Department: 2872)
Optical: systems and elements
Polarization without modulation
By relatively adjustable superimposed or in series polarizers
C359S490020, C359S490020, C359S506000
Reexamination Certificate
active
06348998
ABSTRACT:
DEDICATORY CLAUSE
The invention described herein may be manufactured, used and licensed by or for the Government for governmental purposes without the payment to me of any royalties thereon.
BACKGROUND OF THE INVENTION
Polarization phase plates made of birefringent crystals have long been useful in the study and various applications of polarized light. However, prior art applications of these crystals, typically in sandwich-like layers, exhibited serious problems such as complex angular dependencies of the through-beam geometry for the induced polarization phase shift, little or no fringe spacing adjustment capability and, most severely, exceedingly poor performance for systems that require a large fringe-count having very fine fringe spacing. Prior art applications typically utilized very thin plates (usually less than 1 mm) having very shallow cut angles (usually less than 10°). This is due to the fact that, based on certain assumptions that are well-known in the art regarding the e-ray and o-ray components of the incoming light and the relationship between the wave vector and the power flow vector and polarization and phase-shift dynamics at the air-dielectric interface, a fairly valid analysis could be done on the beam output of a thin-plate assembly. But these assumptions do not result in accurate beam analysis for crystals that are thick enough to be practical to fabricate (between about 1 mm and 1 cm thick) and have significant cut angles. A device is desired that uses such thick crystals and can produce a large count, yet high-quality fringes that are straight, smooth and have a sinusoidal cross-fringe profile and as much as 100% contrast when the input beam is fully linearly polarized and oriented for maximum contrast.
SUMMARY OF THE INVENTION
Applicant's invention is a polarization phase plate assembly (hereinafter referred to as “the Assembly”) comprising at least two uniaxial crystal plates which are identical to each other in structure and dimension and a retarder plate sandwiched between the two crystal plates. Initially the optic axes of the crystal plates are aligned to be parallel with each other. Then the crystal plates are rotated around their normals by an equal twist angle but in opposite directions. When a beam of light is passed through the Assembly, the result is high-quality fringes that vary in number in relation to the degree of the twist angle.
REFERENCES:
patent: 4500178 (1985-02-01), Yeh
patent: 4548479 (1985-10-01), Yeh
patent: 4678287 (1987-07-01), Buhrer
patent: 4772104 (1988-09-01), Buhrer
Bush Freddie M.
Chang Hay Kyung
Shafer Ricky D.
The United States of America as represented by the Secretary of
Tischer Arthur H.
LandOfFree
Polarization phase plate assembly does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polarization phase plate assembly, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polarization phase plate assembly will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2960388