Abstract: Described herein is a quasi-optic rotating joint (100) which allows circularly polarised radiation to be transmitted therethrough irrespective of the angle of rotation of the joint. The rotating joint (100) comprises a first quasi-optic lens (102) having a first axis (112), which is carried on an inner part (116, 118) of bearings (108, 110) and which shares first axis (112). An outer part (122) of bearing (110) carries a quasi-optic mirror (104) and a second quasi-optic lens (106). The second lens (106) has a second axis (114) which is orthogonal to the first axis (112) of the first lens (102) and which intersects at the mirror (104). A Gaussian beam waist is formed at the mirror (104) by the first lens (102) and the second lens (106) is matched to the reflection of the beam waist at the mirror (104). Circularly polarised Gaussian beams passing through the joint (100) suffer a phase shift of angle ? which increases at the same rate as the increase in angle of rotation of the joint (100).

Abstract: Described herein is a quasi-optic rotating joint (100) which allows circularly polarised radiation to be transmitted therethrough irrespective of the angle of rotation of the joint. The rotating joint (100) comprises a first quasi-optic lens (102) having a first axis (112), which is carried on an inner pant (116, 118) of bearings (108, 110) and which shares first axis (112). An outer part (122) of bearing (110) carries a quasi-optic mirror (104) and a second quasi-optic lens (106). The second lens (106) has a second axis (114) which is orthogonal to the first axis (112) of the first lens (102) and which intersects at the mirror (104). A Gaussian beam waist is formed at the mirror (104) by the first lens (102) and the second lens (106) is matched to the reflection of the beam waist at the mirror (104). Circularly polarised Gaussian beams passing through the joint (100) suffer a phase shift of angle &psgr; which increases at the same rate as the increase in angle of rotation of the joint (100).

Abstract: A right circular cylindrical body of an isotropic dielectric such as a cross-linked styrene copolymer, has respective pluralities of mutually parallel grooves formed in its axial end faces, spaced apart by an intermediate portion whose dimension c is a half wavelength. The axial lengths a, b of the grooves are such that when a wave passes through the body, a quarter wavelength phase difference is produced between a component of a wave having its E-vector parallel to the grooves and a component of the wave having its E-vector orthogonal to the grooves. Alternatively the plate may consist of two or more discrete bodies whose grooves are dimensioned to produce a total differential phase shift of one quarter wavelength.