Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/47—Scattering, i.e. diffuse reflection
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/47—Scattering, i.e. diffuse reflection
  • G01N2021/4704—Angular selective
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/47—Scattering, i.e. diffuse reflection
  • G01N2021/4704—Angular selective
  • G01N2021/4711—Multiangle measurement
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/47—Scattering, i.e. diffuse reflection
  • G01N2021/4735—Solid samples, e.g. paper, glass
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2201/00—Features of devices classified in G01N21/00
  • G01N2201/06—Illumination; Optics
  • G01N2201/061—Sources
  • G01N2201/06113—Coherent sources; lasers
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2201/00—Features of devices classified in G01N21/00
  • G01N2201/06—Illumination; Optics
  • G01N2201/068—Optics, miscellaneous

Definitions

• Scatterometry is a set of techniques where light that is scattered away from the specular reflection or in-line transmission directions is measured. Scatterometry is used, for example, to measure and monitor the degree of glossiness of a polished surface (e.g., semiconductor wafers and metals).
• a polished surface e.g., semiconductor wafers and metals.
• Scatterometry can also be used to measure the functional performance of polymer films (e.g., polymeric optical films used in optical devices such as screens on personal devices).
• Some materials such as optically clear adhesives, perform better when they scatter a minimal amount of light away from the inline transmission direction.
• optical diffusers a moderate to high amount of scatter with a particular angular distribution of scattered light is desirable.
• Other methods known in the art include measuring the scattered light distribution (i.e., the intensity of scattered light as a function of angle away from the in-line direction with relatively high (typically, at least 0.2°) angular accuracy). Such methods are useful, for example, for investigating the exact scattered light profile which contains more information about the sample than do measurements at a few discrete angles (e.g., whether there are oscillations in the scatter profile indicating a thin layer or diffractive features on the sample).
• the full scattered light profile obtained with these methods provides more in-depth characterization and analysis of the sample.
• These methods use a collimated beam incident on the sample, and thus provide measurements with lateral resolution at best on the order of 1 mm (the diameter of the incident collimated beam).
• the beam can be focused onto the sample.
• the beam that is reflected from or transmitted through the sample has a natural divergence that must be accounted for.
• the focused scatterometry approach collects the diverging specular reflected or in-line transmitted light, as well as light that is scattered at a few discrete angles.
• the focused scatterometry provides specific haze values, but does not provide high angular resolution measurements.
• polymer films and materials used in display devices it is desirable, for example, for polymer films and materials used in display devices to have both relatively high angular resolution (typically, at least 0.2°) for determining the exact behavior of light in the system and relatively high lateral resolution (typically at least 0.1 mm) for quantifying variations in the scatter profile on the size scale of display pixels.
• relatively high angular resolution typically, at least 0.2°
• relatively high lateral resolution typically at least 0.1 mm
• the present disclosure describes a microscatterometry system comprising, in order: a light source that provides at least one wavelength of light in a range from 400 nm to 700 nm
• an aperture e.g., a variable width aperture
• a first light detector rotatable about a eucentric point
• a light beam i.e., at least one light beam
• a spot having an area in a range from 1 micrometer squared to 625 micrometers squared (in some embodiments, 25 micrometers squared to 225 micrometers squared; in some embodiments, 100 micrometers squared) focused at the eucentric point of the first detector, wherein the focused light diverges after the focal point and the diverging light passes through the aperture before contacting the first light detector, and wherein the sample holder is translatable in a plane orthogonal to the incident light beam.
• the present disclosure describes a method of microscatterometry, the method comprising:
• a sample that is at least one of transmissive or reflective of light of at least one wavelength in a range from 400 nm to 700 nm; an aperture (e.g., a variable width aperture); and
• a first light detector rotatable about a eucentric point
• a light beam i.e., at least one light beam
• a light beam having at least one wavelength of light in a range from 400 nm to 700 nm (in some embodiments, in a range from 442 nm to 633 nm; in some embodiments, at a wavelength of 532 nm)
• the light beam from the light source passes through and is focused by the focusing element to a spot either on or within the sample having an area in a range from 1 micrometer squared to 625 micrometers squared (in some
• micrometers squared 25 micrometers squared to 225 micrometers squared; in some embodiments, 100 micrometers squared), wherein the sample holder translates in a plane orthogonal to the incident light beam, and wherein at least a portion of the light is transmitted through or reflected by the sample to provide scattered light;
• Embodiments of the microscatterometry system, and method for using the same can desirably provide, for example, both relatively high angular and relatively high lateral resolution.
• the method is useful, for example, for generating an angularly resolved scattered light profile from the collected data.
• the Figure is a schematic of an exemplary apparatus described herein.
• microscatterometry system and methods described herein, are useful, for example, for providing analysis of samples such as polymeric materials (e.g., polymer optical films), ceramics (including glass), metals, semiconductors, and paper.
• the analysis may be on samples that are transmissive or reflective of light of at least one wavelength in a range from 400 nm to 700 nm.
• exemplary microscatterometry system 1100 includes light source 1101, focusing element 1103, sample holder 1105, aperture 1107, first light detector 1109 rotatable (1106) about eucentric point 1108. As shown, microscatterometry system 1100 also includes optional optical chopper 1111, optional light beam splitter 1113 used with optional second light detector 1112, and optional beam expanding spatial filter 1114.
• light beam 1102 passes through and is focused by focusing element 1103 to a spot having an area in a range from 1 micrometer squared to 625 micrometers squared (in some embodiments, 25 micrometers squared to 225 micrometers squared; in some embodiments, 100 micrometers squared) focused at eucentric point 1108.
• the focused light diverges after focal point 1104.
• the diverging light passes through aperture 1107 before contacting first light detector 1109.
• Sample holder 1105 is translatable in a plane orthogonal to incident light beam 1102. As shown, sample holder 1105 has sample 1130 mounted therein.
• Sample 1130 is at least one of transmissive or reflective of light of at least one wavelength in a range from 400 nm to 700 nm.
• Light beam 1102 from light source 1101 passes through and is focused by focusing element 1103 to a spot either on or within sample 1130 having an area in a range from 1 micrometer squared to 625 micrometers squared (in some embodiments, 25 micrometers squared to 225 micrometers squared; in some embodiments, 100 micrometers squared).
• sample holder 1105 During operation for a transmissive sample, sample holder 1105 translates such that a portion of sample holder 1105 remains at eucentric point 1108, and optionally rotates about eucentric point 1108. During operation with a reflective sample, sample holder 1105 translates such that a portion of sample holder 1105 remains at eucentric point 1108, and rotates about eucentric point 1108. At least a portion of the light is transmitted through or reflected by sample 1130 to provide scattered light.
• first light detector 1109 rotates (1106) about eucentric point 1108 and collects data generated by the scattered light passing through aperture 1107 onto first light detector 1109.
• an optical axis extends along the incident light beam from the light source towards the sample holder, and is perpendicular to both the lens and the sample holder, and the first light detector is rotatable about the eucentric point in a range from -90° to 90° (in some embodiments, in a range from -45° to 45°, -20° to 20°, -20° to 5°, -10° to 10°, or even -6° to 6°) with respect to the optical axis.
• a specular direction i.e., a direction equal to an angle between an optical axis extending along the incident light beam from the light source towards the sample holder and the direction normal to the sample holder, located in the plane defined by the incident light beam and the normal to the sample holder, on the opposite side of the normal to the sample holder to the incident light beam
• the first light detector is rotatable about the eucentric point in a range from -90° to 90° (in some embodiments, in a range from -45° to 45°, -20° to 20°, -20° to 5°, -10° to 10°, or even -6° to 6°) with respect to the specular direction.
• DOI distinctness-of-image
• DOI is a method of characterizing the degree of glossiness of a surface by looking at the amount of light scattered slightly out of the in-line direction (for transmission) or specular direction (for reflection). It can be used to distinguish between very glossy materials that would have negligible scattering at higher angles, which could not be distinguished with haze measuring instruments.
• Narrow-angle haze is light that is spread at 2° from specular (or in-line), and is calculated from the formula, 100 x 3 ⁇ 4, where 3 ⁇ 4 is the ratio of intensity measured at 2.0° from specular to the measured intensity in the specular direction. Narrow angle haze is used to characterize samples when there are moderate amounts of scatter close to specular, but negligible amounts at high angle.
• Wide-angle haze is used to characterize and distinguish between samples that generally have large amounts of scatter, where the narrow-angle haze and distinctness of image characterizations would not be able to useful.
• Wide-angle haze is light that is spread at a specified degree from specular (or in- line), and is calculated from the formula, 100 x 3 ⁇ 4, or 100 x H15, where 3 ⁇ 4 and H15 are the ratios of intensity measured at 5.0° and 15.0°, respectively, from specular to the measured intensity in the specular direction, respectively.
• Transmission clarity is light that is scattered less than 2.5° from collimated direction, which is normalized to the direct beam intensity with no sample in place.
• Specular gloss is the specular intensity, for 20° or 30° incidence and detection, and is calculated as Rs,2o or R ⁇ o (specular intensity measured at 20° or 30°).
• Embodiments of the microscatterometry system, and methods described herein, are particularly useful for determining the micro-haze of polymeric materials (e.g., polymer optical films), ceramics
• OLED organic light emitting diodes
• AMOLED active-matrix organic light-emitting diodes
• Such handheld devices have a top-emissive architecture and currently do not use any light extraction method except for employing strong microcavity. This strong cavity design can have high light efficiency, but the angular color uniformity is much worse, when compared to that of liquid crystal displays (LCDs).
• This quality of a sample is measureable via a micro-haze uniformity measurement using a microscatterometry system.
• a microscatterometry system and method for using the system are described herein (see "Optical Property Test Method: Micro-Haze Uniformity" described in the Examples, below).
• This test method provides measurements from a sampling beam illuminating a few tens of microns of the sample. In this measurement, the polymeric film surface is scanned with an optical probe that has sub-pixel dimensions while measuring standard deviation in the measured micro-haze levels.
• micro-haze measurement technique allows sample analysis for spatial frequencies corresponding to the peak for human vision perception - namely, spatial frequencies in the range of 1-5 line pairs per millimeter for typical viewing distances.
• the micro-haze measurements allow the examination of size scale variations on the size scale for display pixel dimensions.
• conventional haze measurement systems analyze a large area of the optical film for each measurement and are unable to distinguish visually perceived differences on the critical length scales for pixelated displays.
• Components of the apparatus described herein can be made by techniques known in the art and/or are commercially available, for example, from Melles Griot, Carlsbad, CA or Newport
• the light source provides at least one wavelength of light in a range from 400 nm to 700 nm (in some embodiments, in a range from 442 nm to 633 nm; in some embodiments, at a wavelength of 532 nm).
• Exemplary light sources include lasers (including pulsed lasers), light emitting diodes (LEDs) and arc lamps.
• laser light sources have a power rating for light incident on the sample in a range from 1 milliwatt to 50 milliwatts (in some embodiments, in a range from 1 milliwatt to 25 milliwatts; in some embodiments, a power rating of 10 milliwatts).
• Exemplary lasers are available, for example, from Melles Griot as Model 85-GCB-020, 532nm 20 mW DPSS laser.
• arc lamps have a power rating on the order of watts.
• Exemplary arc lamps are available, for example, from Thorlabs Inc., Newton, NJ, under the trade designation "SLS4001 XENON SHORT- ARC LIGHT SOURCE" (1.3 watt).
• Exemplary focusing elements include lenses (e.g., an objective lens, a singlet lens, or a doublet lens), spatial light modulators, and parabolic mirrors. Such focusing elements are known in the art and can be made or obtained commercially. Exemplary lenses are available, for example, from Newport Corporation (e.g., under the trade designation "PAC058 ACHROMATIC DOUBLET” (1-inch diameter, 150 mm focal length)). Exemplary spatial light modulators are available, for example, under the trade designations "EXULUS SPATIAL LIGHT MODULATOR” from Thorlabs Inc.; "LC 2012” from
• the aperture is a variable aperture (available, for example, under the trade designation "COMPACT ADJUSTABLE WIDTH SLIT M-SV-0.5" from Newport Corporation).
• the microscatterometry system includes a first light detector that rotates about a eucentric point.
• an optical axis extends along the incident light beam from the light source towards the sample holder, and is perpendicular to both the lens and the sample holder, and the first light detector is rotatable about the eucentric point in a range from -90° to 90° (in some embodiments, in a range from -45° to 45°, -20° to 20°, -20° to 5°, -10° to 10°, or even -6° to 6°) with respect to the optical axis.
• a specular direction i.e., a direction equal to an angle between an optical axis extending along the incident light beam from the light source towards the sample holder and the direction normal to the sample holder, located in the plane defined by the incident light beam and the normal to the sample holder, on the opposite side of the normal to the sample holder to the incident light beam
• the first light detector is rotatable about the eucentric point in a range from -90° to 90° (in some embodiments, in a range from -45° to 45°, -20° to 20°, -20° to 5°, -10° to 10°, or even -6° to 6°) with respect to the specular direction.
• Suitable detectors are available, for example, under the trade designation "NEW FOCUS LARGE-AREA PHOTO RECEIVER," Model 2031, from Newport Corporation.
• the microscatterometry system includes an optical chopper.
• Optical choppers are used in conjunction with lock-in amplifiers, where the optical chopper modulates the probe beam, and thus the scattered light, and the lock-in amplifier, measure only the signal detected at the chopping frequency. This is used to increase the signal to noise of the system by rejecting variations in the background light and electronic noise from the detector.
• the optical chopper is positioned between the light source and the focusing element.
• An alternative to using an optical chopper is to use a pulsating light source.
• the optical chopper is a mechanical modulator or an acousto-optic modulator.
• Optical choppers are known in the art and can be made or obtained commercially. Exemplary optical choppers are available, for example, under the trade designation "NEW FOCUS 3501 OPTICAL CHOPPER" from Newport Corporation.
• the optical chopper is positioned between the light source and a beam expanding spatial filter.
• the microscatterometry system includes a beam expanding spatial filter positioned between the light source and the focusing element.
• a beam expanding spatial filter positioned between the light source and the focusing element.
• lasers do not produce a beam with a smooth regular intensity profile. If used as-is, these variations can be misinterpreted as features in a scattered light profile.
• Spatial filters are used to remove irregularities in the beam profile, thus improving the quality of the scattered light profile.
• the input light is focused towards a small pinhole, and the pinhole acts as a point source for light transmitted through it.
• the now diverging light is then collimated with a lens positioned a focal length away from the pinhole.
• a focal length is used such that the now collimated beam is larger in diameter than the beam produced by the laser.
• a larger beam better fills a focusing lens further along the beam, which produces a smaller focused spot than would be produced by the original diameter beam.
• Exemplary spatial filters and beam expanders are available, for example, under the trade designation "COMPACT FIVE-AXIS SPATIAL FILTER MODEL 91 OA,” from Newport Corporation, used with a collimating lens achromatic doublet (1-inch diameter, 50.8 mm focal length; available under the under the trade designation "PAC040”) from Newport Corporation.
• the beam expanding spatial filter is positioned between a light beam splitter and the focusing element.
• the microscatterometry system includes a second light detector.
• a light detector is available, for example, under the trade designation "NEW FOCUS LARGE-AREA
• the second detector is used to monitor variations in the intensity of the light beam coming from the light source.
• the light beam splitter transmits about 90% of the light beam towards the focusing element and reflects about 10% of the light beam towards the second detector.
• the signal from the first detector is divided by the signal from the second detector, to account for variations in the intensity of the light beam.
• the second light detector is positioned between the light source and the focusing element. In some embodiments, the second light detector is positioned between an optical chopper and the focusing element.
• a light beam splitter is used to split a portion of the light beam to the second light detector.
• Exemplary light beam splitters are available, for example, under the trade designations "UV FUSED SILICA METALLIC NEUTRAL DENSITY FILTER FQR-ND01" or "BROADBAND BEAM SAMPLER 10B20NC.1" from Newport Corporation.
• sample mounts e.g., a spring loaded mount (available, for example, under the trade designation "M-PPF50” from Newport Corporation)
• sample stages e.g., linear translation stages (available, for example, under the trade designation "MFA-1C” from Newport Corporation)
• detector stages available, for example, under the trade designation "ROTATION STAGE RV350PE” from Newport Corporation
• goniometric stages available, for example, under the trade designation "GONIOMETRIC STAGE BGM 160 PE” from Newport Corporation
• stage drivers for sample and detector stages (available, for example, under the trade designation "UNIVERSAL MOTION CONTROLLER ESP300” from Newport Corporation)
• detection electronics available, for example, under the trade designation "ANALOG-TO-DIGITAL CONVERTER NI 9215, CDAQ 9172 CHASSIS” from National Instruments, Austin TX).
• a microscatterometry system comprising, in order:
• a light source that provides at least one wavelength of light in a range from 400 nm to 700 nm
• an aperture e.g., a variable width aperture
• a first light detector rotatable about a eucentric point
• a light beam i.e., at least one light beam
• a light beam from the light source passes through and is focused by the focusing element to a spot having an area in a range from 1 micrometer squared to 625 micrometers squared (in some embodiments, 25 micrometers squared to 225 micrometers squared; in some embodiments, 100 micrometers squared) focused at the eucentric point of the first light detector, wherein the focused light diverges after the focal point and the diverging light passes through the aperture before contacting the first light detector, and wherein the sample holder is translatable in a plane orthogonal to the incident light beam.
• the light source is a laser.
• microscatterometry system of Exemplary Embodiment 2A wherein the light source has a power rating in a range from 1 milliwatt to 50 milliwatts (in some embodiments, in a range from 1 milliwatt to 25 milliwatts; in some embodiments, a power rating of 10 milliwatts).
• the focusing element is a lens (e.g., an objective lens, a singlet lens, or a doublet lens).
• microscatterometry system of any of Exemplary Embodiments 7A to 9A further comprising a light beam splitter positioned between the optical chopper and the focusing element to split a portion of a light beam to a second light detector.
• microscatterometry system of Exemplary Embodiment 10A further comprising a beam expanding spatial filter positioned between the light source and the focusing element (e.g., between a light beam splitter and the focusing element).
• microscatterometry system of any of Exemplary Embodiments 1A to 6A further comprising a light beam splitter positioned between the light source and the focusing element to split a portion of a light beam to a second light detector.
• microscatterometry system of Exemplary Embodiment 12A further comprising a beam expanding spatial filter positioned between the light beam splitter and the focusing element.
• microscatterometry system of any of Exemplary Embodiments 1A to 6A further comprising a beam expanding spatial filter positioned between the light source and the focusing element.
• 16A The microscatterometry system of Exemplary Embodiment 15A, further comprising an optical chopper positioned between the light source and the beam expanding spatial filter.
• microscatterometry system of any preceding A Exemplary Embodiment wherein an optical axis extends from the light source (i.e., from where the light emits from the light source when energized) toward the sample holder, and is perpendicular to both the lens and the sample holder, and wherein the first light detector is rotatable about the eucentric point in a range from -90° to 90° (in some
• the microscatterometry system of any preceding A Exemplary Embodiment having a specular direction (i.e., a direction equal to an angle between an optical axis extending along the incident light beam from the light source towards the sample holder and the direction normal to the sample holder, located in the plane defined by the incident light beam and the normal to the sample holder, on the opposite side of the normal to the sample holder to the incident light beam), wherein the first light detector is rotatable about the eucentric point in a range from -90° to 90° (in some embodiments, in a range from -45° to 45°, -20° to 20°, -20° to 5°, -10° to 10°, or even -6° to 6°) with respect to the specular direction.
• specular direction i.e., a direction equal to an angle between an optical axis extending along the incident light beam from the light source towards the sample holder and the direction normal to the sample holder, located in the plane defined by the incident light beam
• a method of microscatterometry comprising:
• a focusing element a sample that is at least one of transmissive or reflective of light of at least one wavelength in a range from 400 nm to 700 nm;
• an aperture e.g., a variable width aperture
• a first light detector rotatable about a eucentric point
• a light beam i.e., at least one light beam
• a light beam having at least one wavelength of light in a range from 400 nm to 700 nm (in some embodiments, in a range from 442 nm to 633 nm; in some embodiments, at a wavelength of 532 nm)
• the light beam from the light source passes through and is focused by the focusing element to a spot either on or within the sample having an area in a range from 1 micrometer squared to 625 micrometers squared (in some
• micrometers squared 25 micrometers squared to 225 micrometers squared; in some embodiments, 100 micrometers squared), wherein the sample holder translates in a plane orthogonal to the incident light beam, and wherein at least a portion of the light is transmitted through or reflected by the sample to provide scattered light;
• the focusing element is a lens (e.g., an objective lens, a singlet lens, or a doublet lens).
• any preceding B Exemplary Embodiment having a specular direction (i.e., a direction equal to an angle between an optical axis extending along the incident light beam from the light source towards the sample holder and the direction normal to the sample holder, located in the plane defined by the incident light beam and the normal to the sample holder, on the opposite side of the normal to the sample holder to the incident light beam), wherein the first light detector is rotatable about the eucentric point in a range from -90° to 90° (in some embodiments, in a range from -45° to 45°, -20° to 20°, -20° to 5°, -10° to 10°, or even -6° to 6°) with respect to the specular direction.
• a specular direction i.e., a direction equal to an angle between an optical axis extending along the incident light beam from the light source towards the sample holder and the direction normal to the sample holder, located in the plane defined by the incident light beam and the normal to the sample
• Micro-Haze Uniformity can be measured on a small lateral scale by focusing a probe beam onto the surface of the sample such that the focused spot is, for example, on the order of 10 micrometers or less. This approach of interrogating a small area of the sample is referred to herein as micro-haze.
• the micro-haze measurement technique allows sample analysis for spatial frequencies corresponding to the peak for human vision perception and on the length scale of the display pixels. Standard haze measurement systems analyze a large area of the optical film and do not show differences on the critical length scales for pixelated displays.
• microscatterometry system 1100 included laser light source 1101 (obtained from Melles Griot, Carlsbad, CA, as Model 85-GCB-020, 532 nm 20 mW DPSS laser), optical chopper (for chopping the light beam) 1 111 (obtained under the trade designation "NEW FOCUS 3501 OPTICAL CHOPPER” from Newport Corporation, Irvine, CA), light beam splitter 1113 (obtained under the trade designation "UV FUSED SILICA METALLIC NEUTRAL DENSITY FILTER FQR-ND01" from Newport Corporation), second light detector 1112 (obtained under the trade designation "NEW FOCUS LARGE-AREA PHOTORECEIVER,” Model 2031 , from Newport Corporation), beam expanding spatial filter (filtering and expanding the light beam) 1114 (obtained under the trade designation "COMPACT FIVE-
• sample holder 1105 (a spring loaded mount (obtained under the trade designation “M-PPF50” from Newport Corporation)), sample to be tested 1130, variable aperture 1107 (obtained under the trade designation “COMPACT ADJUSTABLE WIDTH SLIT M-SV- 0.5” from Newport Corporation), first light detector 1109 (obtained under the trade designation "NEW FOCUS LARGE-AREA PHOTO RECEIVER,” Model 2031 , from Newport Corporation) rotatable
• microscatterometry system included a linear translation stage (obtained under the trade designation "MFA-1C” from Newport Corporation), detector stages (obtained under the trade designation “ROTATION STAGE RV350PE” from Newport Corporation), goniometric stage (obtained under the trade designation "GONIOMETRIC STAGE BGM 160 PE” from Newport
• Light beam splitter 1113 was used to split light beam 1102 to second light detector 1112.
• Light beam splitter 1113 transmitted about 90% of light beam 1102 towards focusing element 1103 and reflected about 10% of light beam 1102 towards second detector 1112.
• Second detector 1112 was used to monitor variations in the intensity of light beam 1102 coming from light source 1101. The signal from first detector 1109 was divided by the signal from second detector 1112, to account for variations in the intensity of light beam 1102.
• sample holder 1105 translated such that a portion of sample holder 1105 remained at eucentric point 1108, and rotated about eucentric point 1108.
• first light detector 1109 rotated (1106) about eucentric point 1108 and collected data generated by the scattered light passing through aperture 1107 onto first light detector 1109.
• the sample was physically scanned relative to the focused spot to take measurements across the film surface and gather statistics for micro-haze uniformity. For each angular position of the first light detector with respect to the in-line direction, the light transmitted through the sample was measured as a function of position across the sample. The measurement at each lateral position took 1 second. In this way, the angular spectrum of scattered light was obtained for each lateral position of interest on the sample. The angle subtended by the first light detector at each angular measurement position was 0.2° in the measurement plane and 0.85° normal to the measurement plane.
• the light intensity proportional to the direct beam (the beam diverging from the focused spot with the same angle as the convergence angle of the original incident beam) and the light intensity proportional to the scattered beam are calculated.
• the direct beam measurement included light between 0° and 5.8° (the angle between the optic axis and the edge of the direct beam, determined by measuring the beam with no sample in place).
• the scattered beam measurement included the light projecting between 5.8° to 15.8° (representative of light scattered out of the direct beam into the first 10° adjacent to the direct beam). From these two values the fractional micro-haze was calculated. This is defined as the ratio of scattered beam intensity to the sum of scattered plus transmitted direct beam.
• the beam was physically chopped at around 2.04 kHz and both the detected signal and the source laser intensity were measured with a lock-in amplifier. This chopping frequency was in the low noise and flat frequency response range of the photodetectors. Lock-in detection enabled intensity measurements over more than 4 orders of magnitude, which is helpful when making measurements of low haze samples, where there is a large difference in the intensities of the direct beam and scattered beam.
• the micro-haze uniformity is defined as the standard deviation of the fractional micro-haze divided by the mean fractional micro-haze measurement itself. In this way, the micro-haze uniformity metric is functionally a noise-to-signal ratio.
• Example 1 the "Optical Property Test Method: Micro-Haze Uniformity" described above was used to obtain microscatterometry profiles of optical glass obtained under the trade designation "FISHERBRAND MICROSCOPE SLIDES 12-550B” from Fisher Scientific, Pittsburgh, PA. The microscatterometry profiles were measured in 10 micrometer steps over 0.5 mm. The micro- haze measurement results are summarized in Table 2, below.
• Diffusive polymeric film examples were fabricated in the general product configuration or embodiment of a single optically diffusing adhesive layer, which is represented in Examples 2-8. Examples 2-8 were coated from 100% solids. Examples 2-8
• Formulations 1-3 were prepared for Examples 2-5 by adding different levels of silicone beads (2.0 micrometers, monodispersed) ("TOSPEARL 120A”) to an adhesive solution prepared as follows (summarized in Table 3, below).
• a monomer premix was prepared by adding 2-ethylhexyl acrylate (“EHA”) (55 parts), isobornyl acrylate (“iBOA”) (25 parts), 2-hydroeyethyl acetate (“HEA”) (20 parts), and 0.02 part of 2-Hydroxy-2- methyl- 1 -phenyl -propan- 1 -one (“D- 1173 ”) .
• EHA 2-ethylhexyl acrylate
• iBOA isobornyl acrylate
• HOA 2-hydroeyethyl acetate
• D- 1173 2-Hydroxy-2- methyl- 1 -phenyl -propan- 1 -one
• the mixture was partially polymerized under a nitrogen (inert) atmosphere by exposure to ultraviolet radiation generated by an ultraviolet light emitting diode (UVA-LED) to provide a coatable syrup having a viscosity of about 1000 centipoise (cps).
• UVA-LED ultraviolet light
• IPvGACURE 651 (0.15 part)
• KBM-403 3-glycioxypropyl trimethoxysilane
• Formulation 3 (2 wt.% particle loading), 6 grams of silicone beads (“TOSPEARL 120A”) were added to 294 grams of adhesive solution and then mechanically stirred using the overhead mixer ("JIFFY LM PINT”) for 2 hours. After mechanical stirring, the admixture was placed on a mixing roller for an additional 24 hours.
• Formulations 4 and 5, for Examples 6 and 7, were prepared by adding differing levels of silicone beads (4.5 micrometers, monodispersed) ("TOSPEARL 145”) to base adhesive material prepared as follows (summarized in Table 4, below).
• a monomer premix was prepared by adding 2-ethylhexyl acrylate (“EHA”) (50 parts), isobornyl acrylate (“iBOA”) (30 parts), 2-hydroxyethyl acrylate (“HEA”) (20 parts), and 0.02 part of 2-Hydroxy-2- methyl-l-phenyl-propan-l-one ("D-l 173").
• EHA 2-ethylhexyl acrylate
• iBOA isobornyl acrylate
• HOA 2-hydroxyethyl acrylate
• D-l 173 2-Hydroxy-2- methyl-l-phenyl-propan-l-one
• HDDA 1,6-hexadiol diacrylate
• IRGACURE 651 alpha, alpha- dimethoxy-alpha-phenylacetophenone
• KBM-403 3-glyciodoxypropyl trimethoxysilane
• TOSPEARL 145 were added to 288.6 grams of base adhesive material. The mixture was then transferred to a closed container and placed on a mixing roller for additional 24 hours.
• Examples of polymeric diffusing films were prepared by knife-coating the corresponding formulation between two silicone -treated release liners at a thickness of either 25 micrometers or 50 micrometers (summarized in Table 5, below).
• the resulting coated material was then exposed to low intensity ultraviolet radiation (a total energy of 1 Joule per square centimeter (J/cm 2 )) having a spectral output from 300-400 nm with a maximum at 351 nm.
• low intensity ultraviolet radiation a total energy of 1 Joule per square centimeter (J/cm 2 )
• a bottle polymer was prepared as Formulation 6, by polymerizing acrylate monomers in the presence of a silicone polymer (30% solid in ethyl acetate), which was prepared according to Example 13 of PCT Pub. No. WO2011/082069A1 modified by replacing m-xylyl-bisoxamic acid trifluoroethyl ester (Example 4 of WO 2011/082069A1) with ethylene-bis-oxamic acid trifluoroethyl ester (Example 3 of PCT Pub. No. WO 2011/082069A1).
• the coating solution was prepared in a 16-ounce (473 ml) jar by mixing butyl acrylate (“BA”) (100 parts), 2-hydroxyethyl acrylate (“HEA”) (0.3 part), the silicone polymer solution (20 parts), and 2,2'-Azobis(2-methylbutyronitrile) (“VAZO 67”) (0.3 part). Additional ethyl acetate was added to adjust weight percent solids to 30 wt.%. Finally, the jar was sealed after bubbling under nitrogen for 20 minutes, and it was transferred to a water bath with controlled temp of 65 °C for 16 hours. This resulted in a hazy coating solution.
• BA butyl acrylate
• HOA 2-hydroxyethyl acrylate
• VAZO 67 2,2'-Azobis(2-methylbutyronitrile)
• the solution was then coated on a silicone coated polyester release liner ("RF12N”) to form a 15-micrometer dry thick adhesive and then laminated with a silicone coated polyester release liner ("RF02N”) after solvent was dried out.
• the resulting pressure sensitive adhesive (PSA) did not have good uniformity.
• An optical micrograph of the resulting PSA was taken. From optical micrographs, the phase separated "particle” sizes (actually not particles, but mixed phase spherical regions formed in situ) were estimated to range from 2-20 micrometers with a volume fraction estimated as approximately 20%.

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