Dr. Bernard C. Kress
Principal Optical Architect at Microsoft Corp
Area of Expertise:
Wearable displays , Micro Optics , Wafer scale optics , Lithography , Holography , Diffractive optics
Profile Summary

Bernard has made over the past two decades significant scientific contributions as an engineer, researcher, associate professor, consultant, instructor, and author.
He has been instrumental in developing numerous optical sub-systems for consumer electronics and industrial products, generating IP, teaching and transferring technological solutions to industry. Application sectors include laser materials processing, optical anti-counterfeiting, biotech sensors, optical telecom devices, optical data storage, optical computing, optical motion sensors, digital image projection, displays, depth map sensors, and more recently head-up and head mounted displays (smart glasses, AR and VR).
His is specifically involved in the field of micro-optics, wafer scale optics, holography and nanophotonics.
Bernard has published numerous books and book chapters on micro-optics and has more than 30 patents granted worldwide. He is a short course instructor for the SPIE and was involved in numerous SPIE conferences as technical committee member and conference co-chair.
He is an SPIE fellow since 2013 as has been recently elected to the board of Directors of SPIE.
Bernard has joined Google [X] Labs. in 2011 as the Principal Optical Architect, and is now Partner Optical Architect at Microsoft Corp, on the Hololens project.
Publications (41)

SPIE Conference Volume | August 2, 2018

PROCEEDINGS ARTICLE | May 29, 2018
Proc. SPIE. 10676, Digital Optics for Immersive Displays

SPIE Conference Volume | September 25, 2017

PROCEEDINGS ARTICLE | June 26, 2017
Proc. SPIE. 10335, Digital Optical Technologies 2017
KEYWORDS: Optical design, Eye, Waveguides, Visualization, Cameras, Sensors, Glasses, Head, Liquid crystal on silicon, Augmented reality, Visual system, Free space optics, Spatial resolution, Head-mounted displays, Virtual reality, Standards development, RGB color model

PROCEEDINGS ARTICLE | October 5, 2015
Proc. SPIE. 9579, Novel Optical Systems Design and Optimization XVIII
KEYWORDS: Defense and security, Consumer electronics, Optical design, Glasses, Video, Head, Augmented reality, Head-mounted displays, Virtual reality, Eyewear

Showing 5 of 41 publications
Conference Committee Involvement (20)
SPIE Digital Optical Technologies
24 June 2019 | Munich, Germany
Digital Optical Technologies
24 June 2019 | Munich, Germany
Optical Design Challenge 2019
3 February 2019 | San Francisco, California, United States
Invited Speakers AR/VR PW19
3 February 2019 | San Francisco, California, United States
Digital Optics for Immersive Displays (DOID18)
24 April 2018 | Strasbourg, France
Showing 5 of 20 published special sections
Course Instructor
SC1125: Design Techniques and Applications Fields for Digital Micro-optics
This course provides an overview of the various design and fabrication techniques available to the optical engineer for micro / nano optics, diffractive optics and holographic optics. Emphasis is put on DFM (Design For Manufacturing) for wafer scale fabrication, Diamond Turning Machining (DTM) and holographic origination. The course shows how design techniques can be tailored to address specific fabrication techniques' requirements and production equipment constraints. The course also addresses various current application fields as in display, imaging, sensing and metrology. :: It is built around 4 sections: (1) design, (2) modeling, (3) fabrication/mass production and (4) application fields. <br/> <p> </p> 1) The course reviews various design techniques used in standard optical CAD tools such as Zemax and CodeV to design Diffractive Optical Elements (DOEs), Micro-Lens Arrays (MLAs), hybrid optics and refractive micro-optics, Holographic Optical Element (HOE), as well as numerical design techniques for Computer Generated Holograms (CGHs). <br/> 2) Modeling single micro optics or complex micro-optical systems including MLAs, DOEs, HOEs, CGHs, and other hybrid elements can be a difficult task when using classical ray tracing algorithms. We review techniques using physical optics propagation to model all diffraction effects, along with systematic or random fabrication errors, multi-order propagation and other effects which cannot be modeled accurately through ray tracing. <br/> 3) Following the design (1) and modeling tasks (2), the optical engineer needs to perform a DFM process so that the resulting design can be fabricated by the desired manufacturing partner/vendor over a specific equipment. We will review such DFM for wafer fab via optical lithography (tape-out process), single point diamond turning (SPDT), or holographic recording specification. The course also reviews fracturing techniques to produce GDSII layout files for specific lithographic fabrication techniques and manufacturing equipment.<br/> 4) This section reviews current application fields for which micro-optics are providing an especially good match, quasi impossible to implement through traditional optics, such as depth mapping sensing (structured illumination based sensor) and augmented reality display (waveguide grating combiner optics). Applications examples in high resolution incremental/absolute optical encoders are also reviewed. Design and modeling techniques will be described for such applications fields, and optical hardware sub-system implementations and micro-optic elements will be shown and demonstrated at the end of the course.
SC454: Fabrication Technologies for Micro- and Nano-Optics
Applications of micro and nano-scale optics are widespread in essentially every industry that uses light in some way. A short list of sample application areas includes communications, solar power, biomedical sensors, laser-assisted manufacturing, and a wide range of consumer electronics. Understanding both the possibilities and limitations for manufacturing micro- and nano-optics is useful to anyone interested in these areas. To this end, this course provides an introduction to fabrication technologies for micro- and nano-optics, ranging from refractive microlenses to diffractive optics to sub-wavelength optical nanostructures. After a short overview of key applications and theoretical background for these devices, the principles of photolithography are introduced. With this backdrop, a wide variety of lithographic and non-lithographic fabrication methods for micro- and nano-optics are discussed in detail, followed by a survey of testing methods. Relative advantages and disadvantages of different techniques are discussed in terms of both technical capabilities and scalability for manufacturing. Issues and trends in micro- and nano-optics fabrication are also considered, focusing on both technical challenges and manufacturing infrastructure.
SC1217: Design, modeling and fabrication techniques for micro-optics: applications to display, imaging, sensing and metrology
This course provides an overview of the various design and fabrication techniques available to the optical engineer for micro / nano optics, diffractive optics and holographic optics. Emphasis is put on DFM (Design For Manufacturing) for wafer scale fabrication, Diamond Turning Machining (DTM) and holographic exposure. The course shows how design techniques can be tailored to address specific fabrication techniques' requirements and production equipment constraints. The course will also address various current application fields such as display, imaging, sensing and metrology. The course is built around 4 points: (1) design, (2) modeling, (3) fabrication/mass production and (4) application fields. We will also review in details the basic micro-optics building blocks and the overall architecture of the iPhone X IR human face sensor. 1) The course will review various design techniques used in standard optical CAD tools such as Zemax and CodeV to design Diffractive Optical Elements (DOEs), Micro-Lens Arrays (MLAs), hybrid optics and refractive micro-optics, Holographic Optical Element (HOE), as well as the various numerical design techniques for Computer Generated Holograms (CGHs). 2) Modeling single micro optics or complex micro-optical systems including MLAs, DOEs, HOEs, CGHs, and other hybrid elements can be a difficult or nearly impossible task when using classical ray tracing algorithms. We will review techniques using physical optics propagation to model not only multiple diffraction effects and their interferences, but also systematic and random fabrication errors, multi-order propagation and other effects which cannot be modeled accurately through ray tracing. 3) Following the design (1) and modeling tasks (2), the optical engineer usually needs to perform a DFM process so that his/her design can be fabricated by the target manufacturing partner/vendor on specific equipment. We will review such DFM for wafer fab via optical lithography (tape-out process), single point diamond turning (SPDT), or holographic optics recording specification. The course also reviews fracturing techniques to produce GDSII layout files for specific lithographic fabrication techniques and manufacturing equipment. 4) In order to point out the potential of such micro-optics for consumer products, this section reviews current application fields for which such elements are providing an especially good match, impossible to implement with traditional optics, such as depth mapping sensing (structured illumination based sensor) and augmented reality display (waveguide grating combiner optics). We will also review applications in high resolution incremental/absolute optical encoders. Design and modeling techniques will be described for such applications fields, and optical hardware sub-system implementations and micro-optics elements will be shown and detailed.
SC1218: Optical Technologies and Architectures for Virtual Reality (VR), Augmented Reality (AR) and Mixed Reality (MR) Head-Mounted Displays (HMDs)
The course provides an extensive overview of the current product offerings as well as the various optical architectures, as in: <br/> - Smart Glasses and Digital Eyewear <br/> - Augmented Reality (AR) and Mixed Reality (MR) headsets <br/> - Virtual Reality (VR) and Merged Reality headsets <br/> The course describes the optical backbone of existing systems, as well as the various optical building blocks, as in: <br/> - Display engines including microdisplay panel architectures, scanner based light engines and phase panels <br/> - Optical combiners integrated either in free space or waveguide platforms <br/> - Depth mapping sensors either though structured illumination or time of flight <br/> - Head tracking, gaze tracking and gesture sensors <br/> Emphasis is set on the design and fabrication techniques to provide the best display immersion and comfort: <br/> - Wearable comfort (size/ weight, CG) <br/> - Visual comfort (eye box size and IPD coverage, angular resolution, FOV, distortion, dynamic range, contrast,…) <br/> - Passive and active foveated rendering and peripheral displays <br/> - VAC (Vergence Accommodation Conflict) mitigation through varifocal, multifocal, spatial and temporal light fields and per pixel depth holographic displays. <br/> The features and limitations of current optical technologies addressing such specifications are reviewed. <p> </p> In order to design next generation head worn systems, one needs to fully understand the specifics and limitations of the human visual system, and design the optics and the optical architecture around such. :: Challenges for next generation systems are reviewed, where immersion and comfort need to be addressed along with consumer level costs requirements. <br/> Finally, the course reviews market analysts’ expectations, projected over the next 5 to 10 years, and lists the main actors (major product design companies, start-ups and optical building block vendors, and current investment rounds in such). Demonstration of some of the state of the art AR, MR and VR headsets will be offered to attendees at the end of the course.
SC1234: Introduction to VR, AR, MR and Smart Eyewear: Market Expectations, Hardware Requirements and Investment Patterns
This course serves as a high level introduction to the various categories of Head Mounted Displays (HMDs) available today: Smart Glasses or Smart Eyewear, Virtual Reality (VR), Augmented Reality (AR), Mixed Reality (MR), and provides a synthetic overview of both current hardware architectures and related markets (enterprise and consumer). <br/> Products limitations and next generation hardware and functionality requirements to fulfill the expected market will be reviewed in a synthetic way.
SC787: Diffractive Optics Technology for Product Development In Transportation, Display, Security, Telecom, Laser Machining and Biomedical Markets
This course provides an introduction to product development using Diffractive Optics technology in today's established and emerging markets. It provides attendees with practical techniques to manage fabrication flows for diffractive optics using available design tools and foundries, and how to interface between them efficiently. The course will be split into three parts: 1) After a short introduction to the diffractive optics concept, the first part of the course will focus on the various diffractive optics design and modeling tools available to an industrial product development department, and how they interface with standard optical design CAD tools and other 3D mechanical design tools in order to provide a global CAD solution for the development of real products. 2) The second part of the course will focus on the various fabrication techniques and technologies available in industry today for the mastering and mass replication of diffractive optical elements. More specifically, we will focus on how a product development manager can manage complex diffractive optics fabrication under various constrains (technology, budget, fabrication time, mass production and time to market). Emphasis will be put on design to fabrication interfacing, fabrication limitations, and fabrication costs analysis as well as fabrication flow control. 3) The third and last part of the course will focus on the various products already on the market including diffractives, and identify the potential future applications including such elements. Six application sectors will be considered in depth: Automotive and Transportation; LED and Laser Displays; Optical Security devices; Optical Telecommunications; Laser Machining and Laser Material processing; and Biomedical applications. The attendee will therefore benefit from a concise and realistic overview of current diffractive optics technology, and thus be able to make the right decision when it comes to weighting the potentiality of using diffractive optics for a specific product development.
SC580: Design and Fabrication Tools for Diffractive Optics
This course is intended to provide attendees with examples of practical tools to design, model, simulate and fabricate Diffractive optics. It is not intended to be a theoretical/mathematical approach to scalar or rigorous electromagnetic theory of diffraction. Emphasis will be put on design to fabrication interfacing, fabrication limitations, fabrication costs analysis as well as fabrication flow control. The attendee will therefor benefit from a realistic view of the current state of the art, and thus be able to make the right decision when it comes to weighting the potentiality of using a diffractive element instead of one or more conventional optical elements.
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