Abstract: An article includes an optical filter that comprises a wavelength selective reflective layer and at least one wavelength selective absorbing layer. The optical filter has visible transmittance between 400 nm-700 nm of less than about 30% and near infrared transmittance at 830 nm-900 nm greater than about 30%.

Abstract: A film stack includes co-stretched first and second layers. The first layer is stained with iodine and has a glass transition temperature of at least 5° C. greater than a glass transition temperature of the second layer. The second layer has in-plane birefringence of less than 0.02 and a retardance of less than 100 nm.

Abstract: An article includes an optical filter that comprises a wavelength selective reflective layer and at least one wavelength selective absorbing layer. The optical filter has visible transmittance between 400 nm-700 nm of less than about 30% and near infrared transmittance at 830 nm-900 nm greater than about 30%.

Abstract: Various embodiments of a respirator that includes a harness, a mask body, and an exhalation valve are disclosed. The exhalation valve can include a valve seat and a flexible flap that is in engagement with the valve seat. The flexible flap can have one or more materials that can cause the flap to flash when moving from a closed position to an open position or vice versa. The flashing valve can make it easier for a user to ascertain whether the valve is operating properly.

Abstract: A display system for sensing a finger of a user applied to the display system includes a display panel; a sensor for sensing the finger; a sensing light source configured to emit a first light having a first wavelength W1; and a reflective polarizer disposed between the display panel and the sensor. For a substantially normally incident light, an optical transmittance of the reflective polarizer versus wavelength for a first polarization state has a band edge such that for a first wavelength range extending from a smaller wavelength L1 to a greater wavelength L2 and including W1, where 30 nm?L2?L1?50 nm and L1 is greater than and within about 20 nm of a wavelength L3 corresponding to an optical transmittance of about 50% along the band edge, the optical transmittance has an average of greater than about 75%.

Abstract: Various embodiments of a respirator that includes a harness, a mask body, and an exhalation valve are disclosed. The exhalation valve can include a valve seat and a flexible flap that is in engagement with the valve seat. The flexible flap can have one or more materials that can cause the flap to flash when moving from a closed position to an open position or vice versa. The flashing valve can make it easier for a user to ascertain whether the valve is operating properly.

Abstract: An optical assembly includes an integral lens assembly having one or more lenses bonded to each other with spaced apart major first and second lens surfaces. First and second optical films are bonded to respective major first and second lens surfaces. The first and second optical films includes a plurality of polymeric layers. Each of the polymeric layers have an average thickness of less than about 500 nm. For a substantially normally incident light and a visible wavelength range the plurality of polymeric layers in the first optical film has an average optical transmittance and an average optical reflectance of greater than about 70% for a first polarization state and an orthogonal second polarization state, respectively. The plurality of polymeric layers in the second optical film has an average optical transmittance of greater than about 70% for at least one of the first and second polarization states.

Abstract: A multilayer optical film includes a plurality of optical repeat units which may number less than about 175 in total and which may have a combined average thickness of less than about 20 micrometers. Each of the optical repeat units includes at least four individual layers which may include at least one polymeric A layer, at least two B layers, and at least one polymeric C layer. At least one layer in the at least four individual layers can have an average thickness of less than about 50 nm. An interlayer adhesion of the individual layers in the plurality of optical repeat units can be at least about 14 grams per inch when measured at a 90 degree peel angle. The multilayer optical film may be a reflective polarizer or a multilayer optical mirror.

Abstract: A film stack includes co-stretched first and second layers. The first layer is stained with iodine and has a glass transition temperature of at least 5° C. greater than a glass transition temperature of the second layer. The second layer has in-plane birefringence of less than 0.02 and a retardance of less than 100 nm.

Abstract: A display system for sensing a finger of a user applied to the display system includes a display panel; a sensor for sensing the finger; a sensing light source configured to emit a first light having a first wavelength W1; and a reflective polarizer disposed between the display panel and the sensor. For a substantially normally incident light, an optical transmittance of the reflective polarizer versus wavelength for a first polarization state has a band edge such that for a first wavelength range extending from a smaller wavelength L1 to a greater wavelength L2 and including W1, where 30 nm?L2?L1?50 nm and L1 is greater than and within about 20 nm of a wavelength L3 corresponding to an optical transmittance of about 50% along the band edge, the optical transmittance has an average of greater than about 75%.

Abstract: A film stack includes an oriented first layer including polyvinyl alcohol disposed on an oriented second layer including naphthalene dicarboxylate containing copolyester resin. The oriented second layer has in-plane birefringence ?nxy<0.02.

Abstract: An optical construction includes a reflective polarizer and an optically diffusive film disposed on the reflective polarizer. The reflective polarizer includes an outer layer including a plurality of first particles partially protruding from a first major surface thereof to form a structured major surface. A first optically diffusive layer is conformably disposed on the structured major surface. The optically diffusive film includes a second optically diffusive layer including a plurality of nanoparticles dispersed therein, and a structured layer including a structured major surface. For a substantially normally incident light and a visible wavelength range from about 450 nm to about 650 nm and an infrared wavelength range from about 930 nm to about 970 nm, the second optically diffusive layer has an average specular transmittance Vs in the visible wavelength range and an average specular transmittance Is in the infrared wavelength range, where Is/Vs?2.5.

Abstract: An optical assembly includes an integral lens assembly having one or more lenses bonded to each other with spaced apart major first and second lens surfaces. First and second optical films are bonded to respective major first and second lens surfaces. The first and second optical films includes a plurality of polymeric layers. Each of the polymeric layers have an average thickness of less than about 500 nm. For a substantially normally incident light and a visible wavelength range the plurality of polymeric layers in the first optical film has an average optical transmittance and an average optical reflectance of greater than about 70% for a first polarization state and an orthogonal second polarization state, respectively. The plurality of polymeric layers in the second optical film has an average optical transmittance of greater than about 70% for at least one of the first and second polarization states.

Abstract: An integral multilayer optical film includes a plurality of interference layers; a structured layer disposed on the interference layers and including a plurality of particles dispersed in a binder; and a barrier layer disposed between the structured layer and the interference layers and co-extruded with the interference layers and the structured layer. The structured layer has a first major surface facing away from the interference layers and a second major surface facing the interference layers. The barrier layer causes the particles to impart a greater surface roughness to the first major surface than the second major surface so that when the optical film is illuminated with a light source, the optical film has a first average effective transmission T1 when the first major surface faces the light source and a second average effective transmission T2 when the first major surface faces away from the light source, where T1-T2?5%.

Abstract: An optical construction includes a reflective polarizer and an optically diffusive film disposed on the reflective polarizer. The reflective polarizer includes an outer layer including a plurality of first particles partially protruding from a first major surface thereof to form a structured major surface. A first optically diffusive layer is conformably disposed on the structured major surface. The optically diffusive film includes a second optically diffusive layer including a plurality of nanoparticles dispersed therein, and a structured layer including a structured major surface. For a substantially normally incident light and a visible wavelength range from about 450 nm to about 650 nm and an infrared wavelength range from about 930 nm to about 970 nm, the second optically diffusive layer has an average specular transmittance Vs in the visible wavelength range and an average specular transmittance Is in the infrared wavelength range, where Is/Vs?2.5.

Abstract: A display system for sensing a finger of a user applied to the display system includes a display panel; a sensor for sensing the finger; a sensing light source configured to emit a first light having a first wavelength W1; and a reflective polarizer disposed between the display panel and the sensor. For a substantially normally incident light, an optical transmittance of the reflective polarizer versus wavelength for a first polarization state has a band edge such that for a first wavelength range extending from a smaller wavelength L1 to a greater wavelength L2 and including W1, where 30 mn?L2?L1?50 nm and L1 is greater than and within about 20 nm of a wavelength L3 corresponding to an optical transmittance of about 50% along the band edge, the optical transmittance has an average of greater than about 75%.

Abstract: A detector system is described that includes a detector that is sensitive to wavelengths in a detection wavelength range. The detector system further includes a light control film that is disposed on the detector and includes a plurality of alternating first and second regions. Each first region has a width W and a height H, where H/W?1. Each first region has a substantially low transmission in a first portion of the detection wavelength range and a substantially high transmission in the remaining portion of the detection wavelength range. Each second region has a substantially high transmission in the detection wavelength range.

Abstract: A retroreflective system is disclosed that includes a retroreflective sheet for retroreflecting light, and a light control film disposed on the retroreflective sheet. For a first wavelength, light incident on the light control film at each of a first and second angles of incidence is retroreflected. For a second wavelength, light incident on the light control film at the first, but not the second, angle of incidence is retroreflected.

Abstract: Film stacks comprise a quarter-wave retarder and a transparent aliphatic cross-linked polyurethane layer disposed on a major surface of the quarter-wave retarder. The transparent aliphatic cross-linked polyurethane layer has a glass transition temperature in a range from 11 to 27° C. and a Tan Delta peak value in a range from 0.5 to 2.5.

Abstract: A film stack comprises an oriented first layer comprising polyvinyl alcohol disposed on an oriented second layer comprising naphthalene dicarboxylate containing copolyester resin. The oriented second layer has in-plane birefringence ?nxy<0.02.