Holograms

A volume phase holographic element characterized in that microvoids between fringes are at least partially filled with a material other than air, said material having a refractive index different from that of the matrix, said matrix comprising branched polyethylenimine and a polymerized ethylenic monomer.

A volume phase holographic element characterized in that microvoids between fringes are at least partially filled with a material other than air, said material having a refractive index lower than that of the matrix, said material having a lower index of refraction is a polymerized fluorinated monomer.

A volume phase holographic element characterized in that microvoids between fringes are at least partially filled with a material other than air, said material having a refractive index different from that of the matrix, wherein said material is a material capable of absorbing light of a wavelength reflected by said holographic element.

The method of forming a holographic element comprising effecting a holographic exposure of a photosensitive element to laser light, developing said exposed photosensitive element to provide a volume phase holographic element having microvoids between the fringes, and at least partially filling said microvoids with a material having a different index of refraction than that of the matrix material of said holographic element, said photosensitive element being a photopolymerizable element.

The method of forming a holographic element comprising effecting a holographic exposure of a photosensitive element to laser light, developing said exposed photosensitive element to provide a volume phase holographic element having microvoids between the fringes, and at least partially filling said microvoids with a material having a different index of refraction than that of the matrix material of said holographic element, said photosensitive element being a photopolymerizable element comprising a dye sensitizer, branched polyethylenimine, and a free radical polymerizable ethylenic unsaturated monomer.

The method of forming a holographic element comprising effecting a holographic exposure of a photosensitive element to laser light, developing said exposed photosensitive element to provide a volume phase holographic element having microvoids between the fringes, and at least partially filling said microvoids by introducing a polymerizable monomer into said microvoids, and then polymerizing said monomer to provide in said microvoids a material having a lower index of refraction than said matrix.

A volume phase holographic element characterized in that microvoids between fringes are at least partially filled with a polymer formed by introducing a monomer into said microvoids and polymerizing said monomer in said microvoids, said polymer having a refractive index different from that of the matrix.