Dr. Bharathwaj A. Narasimhan Profile

Dr. Bharathwaj A. Narasimhan

Staff Engineer at Samsung Display America Lab

SPIE Involvement:

Conference Program Committee | Author

Area of Expertise:

Optical Design , Freeform Optics , Optimization , Virtual Reality Optics , Design of Experiments , Spectroscopy

Publications (16)

Proceedings Article | 21 May 2018 Paper

Ultra-Compact pancake optics based on ThinEyes super-resolution technology for virtual reality headsets

Bharathwaj Narasimhan

Proceedings Volume 10676, 106761G (2018) https://doi.org/10.1117/12.2315688

KEYWORDS: Optical design, Eye, Super resolution, Image resolution, Distortion, Pixel resolution, Modulation transfer functions, Geometrical optics, Virtual reality, Cones

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We present an advanced optical design for a high-resolution ultra-compact Virtual Reality headset based on the traditional pancake configuration following optical foveation in the following sense: Firstly, the magnification is variable along the FoV i.e. the VR pixel density is maximum at the center and gradually diminishes towards the edge. Secondly, the optics image quality is also adapted, so the MTF of any gazable field is best when it is directly gazed. The combination of both is designed to fit with the human visual acuity with normal eye movements, so the user does not perceive the lower peripheral resolution at the edges of the FoV. VR pixel resolution (i.e. pixels per degree) of traditional pancake configuration optics is limited to the geometrical distance of the different elements. However, we have broken that compromise by applying Limbak’s ThinEyes® superresolution technology to the design of four aspherical surfaces in a pancake-type configuration, so the VR pixel resolution is dramatically increased at the center of the virtual reality space while maintaining high FoV and excellent imaging quality across the FoV. We make use of a curved reflective polarizer, which could be done in practice by vacuum molding a polymeric one made out of birefringent multilayer technology (as DBEF of 3M). As an example, we present an optical system that uses a standard 2.85“square display, with a pixel pitch of 35.5 microns (1440x1440 pixels). The total track length (eye pupil to display distance) of the system is 36mm with 15 mm eye relief, so the lens thickness is only 21 mm. For a conventional optical design to achieve a higher VR pixel resolution of 24 pixels per degree, the compromise comes in the form of reduced FoV of around 85 deg. These drawbacks do not bound our take on the pancake configuration. Thanks to the optical foveation, this design achieves a focal length of 49 mm at the center of the FoV, resulting in an outstanding VR pixel resolution of 24 pixels per degree at the center with a circular FoV of 100 deg for a 10mm eyebox.

Proceedings Article | 21 May 2018 Paper

Ultra-compact multichannel freeform optics for 4xWUXGA OLED microdisplays

Marina Buljan, Bharathwaj Narasimhan, Pablo Benítez, Juan Carlos Miñano, Jesús López, Dejan Grabovičkić, Milena Nikolić, Eduardo Pérez, Jorge Gorospe, Eduardo Sanchez, Juan Carlos González, Pablo Zamora, Rubén Mohedano

Proceedings Volume 10676, 1067607 (2018) https://doi.org/10.1117/12.2307452

KEYWORDS: Optical design, Lenses, Organic light emitting diodes, Image resolution, Aspheric lenses, Freeform optics, Prototyping

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Proceedings Article | 27 November 2017 Paper

Freeform aplanatism

J. Miñano, P. Benitez, D. Grabovickic, B. Narasimhan, M. Nikolic, J. Infante

Proceedings Volume 10590, 105900S (2017) https://doi.org/10.1117/12.2286629

KEYWORDS: Optical design, Geometrical optics, Freeform optics, Aberration theory, Nonimaging optics

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Proceedings Article | 26 June 2017 Paper

Advanced freeform optics enabling ultra-compact VR headsets

Pablo Benitez, Juan Miñano, Pablo Zamora, Dejan Grabovičkić, Marina Buljan, Bharathwaj Narasimhan, Jorge Gorospe, Jesús López, Milena Nikolić, Eduardo Sánchez, Carmen Lastres, Ruben Mohedano

Proceedings Volume 10335, 103350I (2017) https://doi.org/10.1117/12.2270317

KEYWORDS: Optical design, Eye, Microlens array, Lenses, Lens design, Image quality, Refraction, Geometrical optics, Freeform optics, Virtual reality, Prototyping

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Proceedings Article | 26 June 2017 Paper

Time multiplexing for increased FOV and resolution in virtual reality

Juan Miñano, Pablo Benitez, Dejan Grabovičkić, Pablo Zamora, Marina Buljan, Bharathwaj Narasimhan

Proceedings Volume 10335, 1033504 (2017) https://doi.org/10.1117/12.2269973

KEYWORDS: Eye, Switching, Organic light emitting diodes, Glasses, Image resolution, Multiplexing, Head, LCDs, Time division multiplexing, Head-mounted displays, Virtual reality, Camera shutters, Multichannel imaging systems, Channel projecting optics

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Proceedings Article | 26 June 2017 Paper

Super-resolution optics for virtual reality

Dejan Grabovičkić, Pablo Benitez, Juan Miñano, Pablo Zamora, Marina Buljan, Bharathwaj Narasimhan, Milena Nikolic, Jesus Lopez, Jorge Gorospe, Eduardo Sanchez, Carmen Lastres, Ruben Mohedano

Proceedings Volume 10335, 103350G (2017) https://doi.org/10.1117/12.2270178

KEYWORDS: Optical design, Eye, Super resolution, Image resolution, Distortion, Lens design, Optical tracking, Modulation transfer functions, Freeform optics, Virtual reality, Prototyping

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Proceedings Article | 29 September 2016 Paper

Design of compact optical systems using multichannel configurations

Milena Nikolic, Juan Miñano, P. Benítez, B. Narasimhan, J. Mendes-Lopes, P. Zamora, M. Buljan, D. Grabovickic

Proceedings Volume 9948, 99480M (2016) https://doi.org/10.1117/12.2237641

KEYWORDS: Optical design, Eye, Solar concentrators, Imaging systems, Head, Head-mounted displays, Optics manufacturing, Nonimaging optics, Prototyping, Multichannel imaging systems

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Proceedings Article | 7 September 2016 Paper

Recent advances in the SMS design method: 3D aplanatism and diffraction

Juan Miñano, P. Benitez, B. Narasimhan, M. Nikolic, J. Mendes-Lopes, D. Grabovickic

Proceedings Volume 9955, 99550D (2016) https://doi.org/10.1117/12.2237402

KEYWORDS: Optical components, Diffraction, Monochromatic aberrations, Mirrors, Optical design, Imaging systems, Wavefronts, Imaging spectroscopy, Freeform optics, Nonimaging optics

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SPIE Journal Paper | 5 April 2016

Optical design through optimization for rectangular apertures using freeform orthogonal polynomials: a case study

Milena Nikolic, Pablo Benítez, Bharathwaj Narasimhan, Dejan Grabovickic, Jayao Liu, Juan Carlos Miñano

OE, Vol. 55, Issue 07, 071204, (April 2016) https://doi.org/10.1117/12.10.1117/1.OE.55.7.071204

KEYWORDS: Optical design, Mirrors, Modulation transfer functions, Optical spheres, Optical engineering, Freeform optics, Aspheric lenses, Computer aided design, LCDs, Optical components

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Proceedings Article | 23 September 2015 Paper

Optical design through optimization using freeform orthogonal polynomials for rectangular apertures

Milena Nikolic, P. Benítez, Juan Miñano, D. Grabovickic, Jiayao Liu, B. Narasimhan, M. Buljan

Proceedings Volume 9626, 96260V (2015) https://doi.org/10.1117/12.2191068

KEYWORDS: Mirrors, Optical design, Patents, Optical spheres, Spatial frequencies, Zernike polynomials, Modulation transfer functions, Freeform optics, Optics manufacturing, Off axis mirrors

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Proceedings Article | 23 September 2015 Paper

Design of freeform aplanatic systems

B. Narasimhan, P. Benitez, Juan Miñano, Julio Chaves, D. Grabovickic, Milena Nikolic, J. Infante

Proceedings Volume 9629, 96290C (2015) https://doi.org/10.1117/12.2190882

KEYWORDS: Monochromatic aberrations, Mirrors, Optical design, Reflection, Imaging systems, Partial differential equations, Differential equations, Palladium, Artificial intelligence, Freeform optics

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Proceedings Article | 3 September 2015 Paper

Design of three freeform mirror aplanat

B. Narasimhan, P. Benitez, Juan Miñano, Julio Chaves, D. Grabovickic, Milena Nikolic, J. Infante

Proceedings Volume 9579, 95790K (2015) https://doi.org/10.1117/12.2189097

KEYWORDS: Monochromatic aberrations, Mirrors, Optical design, Reflection, Imaging systems, Partial differential equations, Palladium, Artificial intelligence, Freeform optics, Optics manufacturing

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Proceedings Article | 25 August 2015 Paper

Freeform aplanatic concentrators

B. Narasimhan, P. Benitez, Juan Miñano, Julio Chaves, D. Grabovickic, Milena Nikolic, J. Infante

Proceedings Volume 9572, 95720M (2015) https://doi.org/10.1117/12.2189092

KEYWORDS: Monochromatic aberrations, Mirrors, Optical design, Solar concentrators, Reflection, Partial differential equations, Differential equations, Palladium, Artificial intelligence, Freeform optics

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Proceedings Article | 22 September 2011 Paper

Investigation of scattering profiles for passive solar light collectors

A. N. Bharathwaj, Balaji Srinivasan

Proceedings Volume 8124, 81240G (2011) https://doi.org/10.1117/12.894206

KEYWORDS: Optical fibers, Optical components, Solar energy, Sun, Scattering, Light scattering, Cobalt, Ray tracing, Diffusers, Solar radiation

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Proceedings Article | 9 February 2011 Paper

A flexible rugged testbed for passive solar collector development

A. N. Bharathwaj, Anand Mishra, B. Srinivasan

Proceedings Volume 7954, 79540L (2011) https://doi.org/10.1117/12.876206

KEYWORDS: Reflectors, Light sources, Light emitting diodes, Solar energy, Sun, Polymers, Microcontrollers, Radiation effects, Solar radiation, Light

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Proceedings Article | 21 August 2009 Paper

A low-cost rugged solution for solar lighting

A. Bharathwaj, Balaji Srinivasan

Proceedings Volume 7423, 74230L (2009) https://doi.org/10.1117/12.825906

KEYWORDS: Mirrors, Light emitting diodes, LED lighting, Sun, Fourier transforms, Buildings, Light sources and illumination, Polymer optical fibers, Fiber optic illuminators, Alignment procedures

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