Optical sensing of cylindrical magnetic domains

Claim 2

In a cylindrical magnetic domain propagation system comprising a magnetic film in which said domains can be propagated, drive field means for moving said domains in a channel extending along said film, and sensing means associated with said channel for sensing the presence and absence of domains at a given point along said channel, said sensing means being characterized in that it comprises means for radiating a beam of plane polarized light of wavelength lambda , a single mode optical waveguide capable of transmitting light in only the HE11 mode at said wavelength lambda , said waveguide having input and output ends, said input end being disposed in light receiving relationship with respect to said beam of plane polarized light, said output end being disposed adjacent to said magnetic film at said given point so that plane polarized light radiating from said output end passes through said film at said given point, and output means disposed on that side of said magnetic film opposite said waveguide in light receiving relationship therewith for providing an output signal that is indicative of the presence or absence of domains at said given point.

Claim 3

A domain propagation system in accordance with claim 1 wherein said means for radiating comprises a laser so disposed with respect to the input end of said waveguide that light therefrom impinges upon the end of said waveguide, and means disposed between said laser and said waveguide for polarizing said laser light.

Claim 4

A domain propagation system in accordance with claim 1 wherein that portion of said waveguide which terminates at said output end is substantially perpendicular to said film.

Claim 5

A domain propagation system in accordance with claim 1 wherein said output means comprises an analyzer plate disposed in receiving relationship with respect to light that has radiated from said waveguide and passed through said magnetic film, and an optical detector disposed adjacent to said analyzer plate.

Claim 6

A domain propagation system in accordance with claim 1 further comprising a mounting plate, means defining a hole through said mounting plate, said output end of said waveguide being disposed in said hole in such a manner that said output end of said waveguide is coplanar with one surface of said plate, said one surface of said plate being mounted on said magnetic film.

Claim 7

A cylindrical magnetic domain propagation system comprising a transparent substrate, a magnetic film disposed on said substrate, said film being of the type in which cylindrical magnetic domains can be propagated, means for moving said domains in a channel extending along said film, means for radiating a beam of plane polarized light of wavelength lambda , a single mode optical waveguide having a core of transparent material having a diameter d and a refractive index n1 and a layer of transparent cladding material disposed on the surface of said core, the refractive index n2 of said cladding material being lower than n1, the diameter d of said core being defined by the equation d < or = (2.4 lambda / pi ) (n12 - n22) 1/2 said waveguide being capable of transmitting light in only the HE11 mode, said waveguide having input and output ends, said input end being disposed in light receiving relationship with respect to said beam of plane polarized light, said output end being disposed adjacent to said magnetic film at said given point so that plane polarized light radiating frOm said output end passes through said film at said given point, and output means disposed on that side of said substrate opposite said waveguide in light receiving relationship therewith for providing an output signal that is indicative of the presence or absence of domains at said given point.

Claim 8

A cylindrical magnetic domain propagation system comprising a transparent substrate, a magnetic film disposed on said substrate, said film being of the type in which cylindrical magnetic domains can be propagated, means for moving said domains in a channel extending along said film, means for radiating a beam of plane polarized light of wavelength lambda , a single mode optical waveguide having a core of transparent material having a diameter d and a refractive index n1 and a layer of transparent cladding material disposed on the surface of said core, the refractive index n2 of said cladding material being lower than n1, the diameter d of said core being defined by the equation d < or = (2.4 lambda / pi ) (n12 - n22) 1/2 said waveguide being capable of transmitting light in only the HE11 mode, said waveguide having input and output ends, said input end being disposed in light receiving relationship with respect to said beam of plane polarized light, said output end being disposed adjacent to said magnetic film at said given point so that plane polarized light radiating frOm said output end passes through said film at said given point, and output means disposed on that side of said substrate opposite said waveguide in light receiving relationship therewith for providing an output signal that is indicative of the presence or absence of domains at said given point.

Claim 9

A cylindrical magnetic domain propagation system in accordance with claim 6 wherein said means for radiating comprises a laser so disposed with respect to the input end of said waveguide that light therefrom impinges upon the end of the core of said waveguide, and means disposed between said laser and said waveguide for polarizing said laser light.

Claim 10

A cylindrical magnetic domain propagation system in accordance with claim 7 wherein said means for radiating further comprises a lens system for focusing light from said laser onto the core of said waveguide.

Claim 11

A cylindrical magnetic domain propagation system in accordance with claim 8, wherein that portion of said waveguide which terminates at said output end is substantially perpendicular to said film.

Claim 12

A domain propagation system in accordance with claim 9 wherein said output means comprises an analyzer plate disposed in receiving relationship with respect to light that has radiated from said waveguide and passed through said magnetic film, and an optical detector disposed adjacent to said analyzer plate.

Claim 13

A domain propagation system in accordance with claim 10 further comprising a mounting plate, means defining a hole through said mounting plate, said output end of said waveguide being disposed in said hole in such a manner that said output end of said waveguide is coplanar with one surface of said plate, said one surface of said plate being mounted on said magnetic film.