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WO2016087442A1 - Capteur optique compact pour la mesure de paramètres physiques - Google Patents

Capteur optique compact pour la mesure de paramètres physiques Download PDF

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Publication number
WO2016087442A1
WO2016087442A1 PCT/EP2015/078214 EP2015078214W WO2016087442A1 WO 2016087442 A1 WO2016087442 A1 WO 2016087442A1 EP 2015078214 W EP2015078214 W EP 2015078214W WO 2016087442 A1 WO2016087442 A1 WO 2016087442A1
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WO
WIPO (PCT)
Prior art keywords
polymer
bragg grating
optical sensor
waveguide structure
optical waveguide
Prior art date
Application number
PCT/EP2015/078214
Other languages
English (en)
Inventor
Kristian Nielsen
Original Assignee
Danmarks Tekniske Universitet
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Danmarks Tekniske Universitet filed Critical Danmarks Tekniske Universitet
Publication of WO2016087442A1 publication Critical patent/WO2016087442A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/35306—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
    • G01D5/35309—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using multiple waves interferometer
    • G01D5/35316—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using multiple waves interferometer using a Bragg gratings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
    • G02B1/045—Light guides
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings
    • G02B6/02076—Refractive index modulation gratings, e.g. Bragg gratings
    • G02B6/0208—Refractive index modulation gratings, e.g. Bragg gratings characterised by their structure, wavelength response

Definitions

  • the present invention relates to an optical sensor and an associated method for measuring physical parameters, such as humidity, strain and temperature.
  • the present invention relates to an optical sensor having a compact and robust design while at the same time being easy to manufacture.
  • the optical sensor of the present invention may be incorporated onto construction elements, such as concrete elements, in order to measure selected physical parameters associated therewith.
  • WO 2007/137429 discloses a fibre Bragg grating (FBG) humidity sensor comprising an optical fibre having two Bragg gratings.
  • One of the Bragg gratings is sensitive to humidity whereas the other Bragg grating is sensitive to temperature.
  • the humidity sensitive Bragg grating is coated with a specific polymer which expands when it is exposed to humidity. The expansion of the specific polymer introduces a transverse strain in the grating area of the optical fibre. A direct relation between the amount of strain and humidity percentage can be deduced therefrom.
  • WO 2014/062672 discloses a fibre Bragg grating (FBG) sensor for detecting moisture.
  • the sensor may include a sensor housing, a FBG cable, water-swellable bead(s) and a retaining mechanism.
  • the housing secures the FBG cable and water-swellable bead.
  • the retaining mechanism such as one or more wire(s) placed adjacent to the FBG cable, may be utilized to minimize lateral displacement of the water-swellable bead(s).
  • the water-swellable bead(s) may swell as they absorb water, thereby causing the FBG to be strained to allow the detection of liquid moisture.
  • CN 202 869 694 relates to a fibre Bragg grating (FBG) temperature and humidity sensor.
  • the sensor comprises a fibre having a temperature sensitive element and a humidity sensitive element.
  • the surface of the fibre Bragg grating of the humidity sensing part of the sensor element is coated with a polyimide layer having a thickness of 30-50 ⁇ .
  • the fibre Bragg grating humidity sensing element is also sensitive to a change of temperature and humidity, whereas the fibre Bragg grating temperature sensing part is only sensitive to a change of environment temperature.
  • the temperature value and the humidity value of the measured environment can be obtained at the same time.
  • Multiple sensing elements can be connected in series so as to measure the temperature field and the humidity field of a complex environment.
  • an optical sensor adapted to measure at least three physical parameters
  • said optical sensor comprising a polymer-based optical waveguide structure comprising : a) a first Bragg grating structure being adapted to provide information about a first physical parameter, b) a second Bragg grating structure being adapted to provide information about a
  • a third Bragg grating structure being adapted to provide information about a third physical parameter wherein the first, second and third Bragg grating structures are at least partly spatially overlapping in the polymer-based optical waveguide structure.
  • the present invention relates to an optical sensor for measuring three physical parameters.
  • these three parameters are humidity, strain and temperature.
  • polymer-based optical waveguide structure is here to be understood as any wave guiding structure comprising a polymer material within its light guiding core.
  • the light guiding core may comprise non-polymer materials, including dopants, as well. Such dopants may increase or target the sensitivity of the optical sensor in relation to specific materials surrounding the optical sensor.
  • cross-linker may make the polymer more hydrophilic and thereby more sensitive to humidity.
  • dopants in the form of iron particles may make the optical sensor more corrosion sensitive.
  • dopants may include a variety of rare earth materials in order to increase and/or target the sensitivity of the optical sensor.
  • the polymer base material of the core may be polymethylmethacrylate (PMMA) .
  • the polymer-based optical waveguide structure is a single-mode or few-mode polymer-based optical fibre structure.
  • the term "few mode" is here to be understood as multi-mode although only a few modes are supported by the polymer-based optical fibre structure.
  • the cladding as well as the cap of the optical fibre structure may comprise materials like metal, semiconductors, ceramics etc.
  • first, second and third Bragg grating structures are at least partly spatially overlapping ensures that a very compact sensor design may be obtained.
  • polymer-based optical waveguides are more elastic and deformable and thereby also more sensitive to external perturbations compared to silica-based waveguides. This implies for example, that strain levels up to at least 7% may be measured. In comparison strain levels of only 0.5% may be measured using silica-based waveguides.
  • the polymer-based optical waveguide structure may comprise a polymer-based optical fibre, such as a single-mode polymer-based micro-structured optical fibre.
  • the single-mode property of the polymer-based micro-structured optical fibre contributes to enhancing the sensitivity of the sensor compared to multi-mode based sensor arrangements.
  • Information about humidity, strain and temperature is provided by light reflected from the three Bragg gratings. More particularly, information about these parameters is provided via a wavelength shift of the reflected light.
  • Reflected light from the three Bragg grating structures provide information about all three physical parameters, namely humidity, strain and temperature.
  • Information about these parameters may be achieved by solving the following set of equals: where f l r f 2 and f 3 are the reflected wavelengths of the Bragg grating structures, and where T, H and E represent measures for the humidity, strain and temperature, respectively.
  • the coefficients of the matrix, a nm are determined and calibrated ones from associated values of fi and T, f 2 and H, and f 3 and E. From thereon T, H and E are determinable directed from measured values of f lf f 2 and f 3 , i.e. the reflected wavelengths of the Bragg grating structures.
  • the optical sensor of the present invention may further comprise a broadband light source and appropriate means for injecting or coupling light into the polymer-based optical waveguide structure along with appropriate means for detecting and spectrally analysing light reflected from the three spatially overlapping Bragg gratings. From these measurements the wavelengths f lf f 2 and f 3 may be determined.
  • the broadband light source may in principle involve any type of broadband light source, for example broadband light sources emitting light in the visible range. Suitable light source candidates are super luminescent diodes (SLD), semiconductor optical amplifiers (SOA), super continuum fibre lasers or white light lasers, such as SuperK light sources.
  • SLD super luminescent diodes
  • SOA semiconductor optical amplifiers
  • the broadband light source may emit light in for example the 300-1600 nm range, such as in the 400-1000 nm range. However, other wavelength ranges are applicable as well.
  • the light from the broadband light source may reach the three spatially overlapping Bragg gratings via a fibre coupler, such as a 3 dB fibre coupler.
  • a fibre coupler such as a 3 dB fibre coupler.
  • the same fibre coupler may also ensure that reflected light from the three Bragg gratings is able to leave the waveguide in order to be analysed by a spectrometer, such as a CCD spectrometer.
  • the reflections from the three Bragg gratings may thus be analysed by for example a line CCD spectrometer.
  • the broadband light source and the detector means may be implemented in one single unit, such as an optical interrogator.
  • the present invention relates to a method for determining at least three physical parameters using an optical sensor comprising spatially overlapping first, second and third Bragg grating structures arranged in a polymer-based optical waveguide structure, the method comprising the step of solving the following set of equations: where f l r f 2 and f 3 are the reflected wavelengths of the first, second and third Bragg grating structures, respectively, and wherein T, H and E represent the at least three physical parameters to be determined.
  • the polymer-based optical waveguide structure may have the properties discussed in relation to the first aspect.
  • the first, second and third physical parameters relates to temperature (T), humidity (H) and strain (E), respectively.
  • the present invention relates to a method for manufacturing an optical sensor adapted to measure at least three physical parameters, the method comprising the steps of: a) establishing a first Bragg grating structure in a polymer-based optical waveguide structure, b) establishing a second Bragg grating structure in the polymer-based optical waveguide structure, c) establishing a third Bragg grating structure in the polymer-based optical waveguide structure, wherein the first, second and third Bragg grating structures are at least partly spatially overlapping in the polymer-based optical waveguide structure.
  • the polymer-based optical waveguide structure may have the properties discussed in relation to the first aspect.
  • the first, second and third Bragg grating structures may be established using various techniques, such as ultra-violet (UV) writing or one or more phase masks.
  • UV writing the applied wavelength may be in the range 300-500 nm.
  • the Bragg grating structures may be adapted to reflect light in the 400-1000 nm range, such as in the 500-900 nm range. It should be noted however that other wavelength ranges may be applicable as well. For example, other waveguide materials than polymers may require the use of other wavelength ranges in order to minimize loses.
  • the method of manufacturing of the first, second and third Bragg grating structures may be optimized when using phase masks in that one Bragg grating structure may be induced by the first order diffraction pattern of a phase mask whereas another Bragg grating structure may be induced by a higher order diffraction pattern of the same phase mask.
  • two Bragg grating structures reflecting light at 850 nm and 569 nm may be manufactured in this way by using the 1 st order interference for the 850 nm Bragg grating structure and interference between the 1 st and 2 nd order for the 569 nm Bragg grating structure.
  • Fig. 1 shows spatially overlapping Bragg grating structures
  • Fig. 2 shows an optical sensor according to an embodiment of the present invention
  • Fig. 3 shows a micro-structured single-mode optical fibre of a type being applicable in the present invention.
  • the present invention relates to an optical sensor and an associated method for measuring a first, a second and a third physical parameter. These parameters involve measurements of humidity, strain and temperature.
  • the present invention further relates to a method for manufacturing a compact optical sensor.
  • Optical sensors according to the present invention may advantageously be used to monitor concrete structures by embedding sensors into the concrete material.
  • Fig. 1 the essential parts of the optical sensor of the present invention are depicted. Compared to a complete sensor the broadband light source and the optical analysing and detection system are not shown. Preferably, the broadband light source and the analysing and detection system form part of a single unit, i.e. an optical interrogator.
  • the sensor 100 includes a polymer-based wave guiding structure having a core region 101 with three Bragg gratings 102, 103, 104 arranged therein.
  • the Bragg gratings 103 and 104 are depicted below the Bragg grating 102.
  • Bragg gratings 103 and 104 are of course inside the core region 101 as well.
  • the three Bragg gratings 102, 103, 104 are spatially overlapping.
  • polymer-based is to be understood as any wave guiding structure comprising a polymer material within its core.
  • the core may however comprise additional materials, such as dopants, as well.
  • the additional core material may be selected to increase or target the sensitivity in relation to specific materials surrounding the optical sensor. Possible dopants may include a variety of rare earth materials.
  • the cladding as well as the cap surrounding the core may comprise materials like metal, semiconductors, ceramics etc.
  • the wave guiding structure comprises a polymer-based optical fibre, such as a single-mode or few-mode polymer-based micro-structured optical fibre.
  • the single-mode or few-mode property of the polymer-based micro-structured optical fibre contributes to enhancing the sensitivity of the sensor compared to multi-mode based sensor arrangements.
  • a Bragg grating is a structure where the index of refraction varies in a periodic manner along the length of the grating.
  • the periods of the Bragg gratings are selected in view of the wavelength of the light source injecting light into the sensor 100. As illustrated in Fig. 1 the periods of the three Bragg gratings 102, 103 and 104 are slightly different in order to reflect slightly different wavelengths. Also, the three Bragg gratings 102, 103 and 104 are arranged in a manner so that they overlap spatially and thereby form a compact structure.
  • the Bragg gratings 102, 103 and 104 reflect light in the 400-1000 nm range, such as in the 500-900 nm range. However, other wavelength ranges are applicable as well.
  • the reflected light from the three Bragg gratings 102, 103 and 104 may for example peak at 520 nm, 776 nm and 846 nm.
  • the Bragg gratings may be induced into the core region 101 by various techniques, such as by UV writing or illumination through one or more phase masks.
  • phase masks In case phase masks are used two Bragg gratings can be induced simultaneously by using the first order diffraction pattern as well as a higher order diffraction pattern from the same phase mask.
  • the following set of equations are to be solved :
  • f lr f 2 and f 3 are the reflected wavelengths of the Bragg gratings
  • T, H and E are measures for the humidity, strain and temperature, respectively.
  • the coefficients of the matrix, a nm are calibration values.
  • the nine coefficients of the 3x3 matrix may be determined ones and for all .
  • the matrix coefficients, a nm being known the humidity, strain and temperature may be determined from measurement of the reflected wavelengths
  • the reflected wavelengths f lr f 2 and f 3 are measured using an optical interrogator 205 as shown in Fig. 2.
  • the optical interrogator comprises a broadband light source 201, such as a broadband light sources emitting light in the visible range.
  • suitable light source candidates are SLDs, SOAs, super continuum fibre lasers or white light lasers, such as SuperK light sources.
  • the emitted light is coupled into the optical fibre 204 via a 3 dB splitter.
  • a filter 202 such as a diffracting element, a tuneable filter or another type of spectrum analysing equipment.
  • the filter 202 and the detector 203 from an optical spectrometer for detecting and spectrally analysing light reflected from the three Bragg gratings.
  • the waveguide structure is formed by a single-mode or few-mode optical fibre where at least the core region comprises a polymer material, such as for example PMMA.
  • the polymer core region may comprise dopants.
  • a plurality of longitudinally arranged holes may be provided around the centre of the core region in order to enhance the single-mode/few-mode properties of the optical fibre.
  • Fig. 3 shows an example of a cross-sectional view of an endlessly single-mode polymer- based optical fibre.
  • the single-mode property of the optical fibre is independent of the wavelength of the light propagating within the fibre.
  • the core region is surrounded by a plurality of holes arranged in a periodic pattern. The holes extend in the longitudinal direction of the optical fibre.
  • the solid core region itself has a diameter of around 10 ⁇ . It is should be noted however that step index optical fibres may also be used as wave guiding structures in relation to the present invention.
  • the inventors have performed experiments where light is reflected from the three Bragg gratings at 520 nm, 776 nm and 846 nm.
  • the 520 nm peak was used to measure the relative humidity
  • the 776 nm peak was used to measure the temperature
  • the 846 nm peak was intended to measure strain.
  • an unstrained setup i.e. no strain applied, corresponding values of relative humidity and temperature of 19.8% and 38.4 °C have been measured.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optical Transform (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

La présente invention concerne un capteur optique conçu pour mesurer au moins trois paramètres physiques, ledit capteur optique comprenant une structure de guide d'ondes optique à base de polymère comprenant une première, une deuxième et une troisième structure à réseau de Bragg. Les première, deuxième et troisième structures de réseau à Bragg se chevauchent au moins partiellement dans l'espace dans la structure de guide d'ondes optique à base de polymère et forment ainsi une structure de capteur compact. L'invention concerne également un procédé permettant de mesurer le premier, le deuxième et le troisième paramètre physique, et un procédé de fabrication du capteur optique.
PCT/EP2015/078214 2014-12-01 2015-12-01 Capteur optique compact pour la mesure de paramètres physiques WO2016087442A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP14195653 2014-12-01
EP14195653.2 2014-12-01

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Publication Number Publication Date
WO2016087442A1 true WO2016087442A1 (fr) 2016-06-09

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Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11194159B2 (en) 2015-01-12 2021-12-07 Digilens Inc. Environmentally isolated waveguide display
US11281013B2 (en) 2015-10-05 2022-03-22 Digilens Inc. Apparatus for providing waveguide displays with two-dimensional pupil expansion
US11442222B2 (en) 2019-08-29 2022-09-13 Digilens Inc. Evacuated gratings and methods of manufacturing
US11448937B2 (en) 2012-11-16 2022-09-20 Digilens Inc. Transparent waveguide display for tiling a display having plural optical powers using overlapping and offset FOV tiles
US11543594B2 (en) 2019-02-15 2023-01-03 Digilens Inc. Methods and apparatuses for providing a holographic waveguide display using integrated gratings
US11586046B2 (en) 2017-01-05 2023-02-21 Digilens Inc. Wearable heads up displays
US11703645B2 (en) 2015-02-12 2023-07-18 Digilens Inc. Waveguide grating device
US11726323B2 (en) 2014-09-19 2023-08-15 Digilens Inc. Method and apparatus for generating input images for holographic waveguide displays
US11726332B2 (en) 2009-04-27 2023-08-15 Digilens Inc. Diffractive projection apparatus
US11747568B2 (en) 2019-06-07 2023-09-05 Digilens Inc. Waveguides incorporating transmissive and reflective gratings and related methods of manufacturing
US12140764B2 (en) 2019-02-15 2024-11-12 Digilens Inc. Wide angle waveguide display
US12158612B2 (en) 2021-03-05 2024-12-03 Digilens Inc. Evacuated periodic structures and methods of manufacturing
US12210153B2 (en) 2019-01-14 2025-01-28 Digilens Inc. Holographic waveguide display with light control layer
US12298513B2 (en) 2016-12-02 2025-05-13 Digilens Inc. Waveguide device with uniform output illumination
US12306585B2 (en) 2018-01-08 2025-05-20 Digilens Inc. Methods for fabricating optical waveguides
US12366823B2 (en) 2023-07-17 2025-07-22 Digilens Inc. Systems and methods for high-throughput recording of holographic gratings in waveguide cells

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US5380995A (en) * 1992-10-20 1995-01-10 Mcdonnell Douglas Corporation Fiber optic grating sensor systems for sensing environmental effects
US5591965A (en) * 1995-05-08 1997-01-07 Udd; Eric Multiparameter sensor system using a multiple grating fiber optic birefringent fiber
WO2002095329A1 (fr) * 2001-05-25 2002-11-28 Optoplan As Detecteur optique distribue a structure de detection a reseau de bragg
WO2007137429A1 (fr) 2006-05-31 2007-12-06 Itf Laboratories Inc. Capteur d'humidité à réseau de bragg en fibres à sensibilité améliorée
US20090123111A1 (en) * 2006-02-22 2009-05-14 Hansen Medical, Inc. Optical fiber grating sensors and methods of manufacture
WO2010030251A2 (fr) * 2008-09-15 2010-03-18 Agency For Science, Technology And Research Capteurs optiques intégrés fonctionnant dans le domaine fréquentiel
US20110026871A1 (en) * 2009-08-03 2011-02-03 Nitto Denko Corporation Sensor element
CN202869694U (zh) 2012-11-13 2013-04-10 长城信息产业股份有限公司 一种光纤光栅温度/湿度传感器
WO2014062672A1 (fr) 2012-10-15 2014-04-24 Gangbing Song Systèmes et procédés à réseau de bragg sur fibre pour la détection d'humidité

Patent Citations (9)

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Publication number Priority date Publication date Assignee Title
US5380995A (en) * 1992-10-20 1995-01-10 Mcdonnell Douglas Corporation Fiber optic grating sensor systems for sensing environmental effects
US5591965A (en) * 1995-05-08 1997-01-07 Udd; Eric Multiparameter sensor system using a multiple grating fiber optic birefringent fiber
WO2002095329A1 (fr) * 2001-05-25 2002-11-28 Optoplan As Detecteur optique distribue a structure de detection a reseau de bragg
US20090123111A1 (en) * 2006-02-22 2009-05-14 Hansen Medical, Inc. Optical fiber grating sensors and methods of manufacture
WO2007137429A1 (fr) 2006-05-31 2007-12-06 Itf Laboratories Inc. Capteur d'humidité à réseau de bragg en fibres à sensibilité améliorée
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Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11726332B2 (en) 2009-04-27 2023-08-15 Digilens Inc. Diffractive projection apparatus
US11448937B2 (en) 2012-11-16 2022-09-20 Digilens Inc. Transparent waveguide display for tiling a display having plural optical powers using overlapping and offset FOV tiles
US11726323B2 (en) 2014-09-19 2023-08-15 Digilens Inc. Method and apparatus for generating input images for holographic waveguide displays
US11726329B2 (en) 2015-01-12 2023-08-15 Digilens Inc. Environmentally isolated waveguide display
US11194159B2 (en) 2015-01-12 2021-12-07 Digilens Inc. Environmentally isolated waveguide display
US11740472B2 (en) 2015-01-12 2023-08-29 Digilens Inc. Environmentally isolated waveguide display
US11703645B2 (en) 2015-02-12 2023-07-18 Digilens Inc. Waveguide grating device
US11281013B2 (en) 2015-10-05 2022-03-22 Digilens Inc. Apparatus for providing waveguide displays with two-dimensional pupil expansion
US11754842B2 (en) 2015-10-05 2023-09-12 Digilens Inc. Apparatus for providing waveguide displays with two-dimensional pupil expansion
US12298513B2 (en) 2016-12-02 2025-05-13 Digilens Inc. Waveguide device with uniform output illumination
US11586046B2 (en) 2017-01-05 2023-02-21 Digilens Inc. Wearable heads up displays
US12248150B2 (en) 2017-01-05 2025-03-11 Digilens Inc. Wearable heads up displays
US12306585B2 (en) 2018-01-08 2025-05-20 Digilens Inc. Methods for fabricating optical waveguides
US12210153B2 (en) 2019-01-14 2025-01-28 Digilens Inc. Holographic waveguide display with light control layer
US11543594B2 (en) 2019-02-15 2023-01-03 Digilens Inc. Methods and apparatuses for providing a holographic waveguide display using integrated gratings
US12140764B2 (en) 2019-02-15 2024-11-12 Digilens Inc. Wide angle waveguide display
US11747568B2 (en) 2019-06-07 2023-09-05 Digilens Inc. Waveguides incorporating transmissive and reflective gratings and related methods of manufacturing
US12271035B2 (en) 2019-06-07 2025-04-08 Digilens Inc. Waveguides incorporating transmissive and reflective gratings and related methods of manufacturing
US11592614B2 (en) 2019-08-29 2023-02-28 Digilens Inc. Evacuated gratings and methods of manufacturing
US11899238B2 (en) 2019-08-29 2024-02-13 Digilens Inc. Evacuated gratings and methods of manufacturing
US11442222B2 (en) 2019-08-29 2022-09-13 Digilens Inc. Evacuated gratings and methods of manufacturing
US12158612B2 (en) 2021-03-05 2024-12-03 Digilens Inc. Evacuated periodic structures and methods of manufacturing
US12366823B2 (en) 2023-07-17 2025-07-22 Digilens Inc. Systems and methods for high-throughput recording of holographic gratings in waveguide cells

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