3m Innovative Properties Company

John A Wheatley

Michael F Weber

Andrew John Ouderkirk

Olester Benson, Jr

Timothy J Nevitt

William Ward Merrill

Robert L Brott

James M Jonza

Yaoqi Joe Liu

Mark B O'Neill

Laurence R Gilbert

Bruce A Nerad

Gary B Hanson

Kelly M Roscoe

Benjamin T Fellows

Mel Y Wong

Wilson C Garland

Multilayer polymeric films and other optical bodies are provided. The films, which have at least three layers of different composition in the optical repeating unit, reflect light in a first portion of the spectrum while transmitting light in a second portion of the spectrum, exhibit improved reflectivities at oblique angles, and can be designed to suppress one or more higher order harmonics of the main reflection band.

Multicomponent optical body

In a multilayer dielectric reflector, treating the surface of the reflector selectively increases the amount of light transmitted through the reflector. Various surface treatments can be used to permit light to transmit through the reflector that would otherwise be reflected by the reflector. In one such reflector, different portions of the surface have different coupling efficiencies for coupling light having a high propagation angle into the multilayer reflector. Those portions having higher coupling efficiencies on each side of the reflector have a higher degree of transmission.

Multilayer reflector with selective transmission

The present invention provides reflective films and other optical bodies which exhibit sharp bandedges on one or both sides of the main reflection bands. The optical bodies comprise multilayer stacks M.sub.1 and M.sub.2, each having first order reflections in a desired part of the spectrum and comprising optical repeating units R.sub.1 and R.sub.2, respectively. At least one of the optical repeating units R.sub.1 and R.sub.2 varies monotonically in optical thickness along the thickness of the associated multilayer stack.

Optical film with sharpened bandedge

Various combinations of retroreflective sheeting and multilayer polymeric reflective films are disclosed. The reflective film includes alternating layers of at least a first and second polymer, the alternating layers being configured to exhibit a high reflectance for light within a first spectral range and a low reflectance for light within a second spectral range. At least two of the alternating layers can have out-of-plane indices of refraction which differ by no more than 50% of the maximum in-plane refractive index difference. The polymeric layers can define optical repeating units arranged in a sequence to have a specific thickness profile designed to give sharpened spectral transitions. The retroreflective layer preferably exhibits retroreflectance in all planes of incidence, but alternately it can be retroreflective in at least one plane of incidence but not in at least one other plane of incidence.

Retroreflective dichroic reflector

A reflective article has a multilayer film covering a patterned retroreflective layer. In one embodiment the patterned retroreflective layer includes a separate indicia layer covering a retroreflective substrate. The indicia are substantially hidden under normal viewing conditions but easily detectable under retroreflective lighting conditions. Various types of retroreflective layers are disclosed. The article can also include microstructured relief patterns which produce holographic images under ambient lighting but which disappear under retroreflective conditions. The multilayer film includes alternating layers of at least a first and second polymer, and has a relatively high reflectivity for normally incident light within a first spectral range which is approximately coextensive with the visible spectrum, and a relatively low reflectance for normally incident light within a second spectral range. The second spectral range can include a transmission window of 15% or less fractional bandwidth located at least partially in the visible spectrum. Film constructions are disclosed which achieve sharper spectral transitions than previously attainable. Film constructions are also disclosed which preserve such sharp transitions even at high entrance (tilt) angles.

Reflective article with concealed retroreflective pattern

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Ascot, United Kingdom

John A Wheatley