Synopsys, Inc. · NASDAQ:SNPS
Synopsys — Technical Presentation (October 2020)
36 slides from Synopsys's technical presentation, October 2020
Slide 1: Designing Augmented/Virtual Reality Devices using Multi-Domain Optical Simulations
Designing Augmented/Virtual Reality Devices using Multi-Domain Optical Simulations Simulation and Design Using RSoft Tools and LightTools
Slide 2: Optics is Key for VR/AR
Optics is Key for VR/AR • “Optics remains the key challenge in developing the ultimate virtual experience” Bernard Kress, Microsoft's Hololens Division @ SPIE Photonics West 2018: • New types of optical and photonics technologies need to be implemented in next-generation VR/AR systems in order to pr
Slide 3: AR/VR Requirements
AR/VR Requirements • Main VR/AR requirements: – Low weight – Small Size – Insensitive to vibration – Comfortableness • Types of existing systems include: – Freeform optical prisms projection systems – Retina scanning – Reflective systems or hybrid reflective/refractive systems – Optical planar waveg
Slide 4: Basic Schematic of Optical Waveguide System
Basic Schematic of Optical Waveguide System Near-Eye-Display (NED) Systems • Diffractive Gratings Functions: – Couple light into waveguide plate and couple light out of plate into eyes – Wavelength selection – Wavefront reshaping • Gratings must be designed properly so that the optical system produc
Slide 5: RSoft and LightTools Co-Simulation
RSoft and LightTools Co-Simulation • RSoft Component Tools • LightTools – Based on physical optics – Based on geometrical optics – Maxwell’s equations, etc – Snell’s law, etc. – Small photonics devices – Large bulk optical system – Wave propagation and multi-physics – Ray tracing and beam propagatio
Slide 6: Simulating the Grating with RSoft Device Tools
Simulating the Grating with RSoft Device Tools © 2020 Synopsys, Inc. 6
Slide 7: DiffractMOD: RSoft's RCWA tool
DiffractMOD: RSoft’s RCWA tool • DiffractMOD is a very efficient tool to rigorously calculate diffraction properties of transversely periodic devices • DiffractMOD outputs : – Reflection/Transmission power for each diffraction order – Total reflection/transmission – Amplitude/Phase/Angle for each di
Slide 8: RSoft/LightTools BSDF Interface
RSoft/LightTools BSDF Interface • RSoft BSDF files: – Automatically calculated using RSoft’s FullWAVE or DiffractMOD packages – Contains information about how a surface (thin film, patterns, etc) scatters light – Reflection/transmission data is stored for illumination from both sides of the surface
Slide 9: Design Case 1
Design Case 1 © 2020 Synopsys, Inc. 9
Slide 10: Use LightTools to Design the Nominal System
Use LightTools to Design the Nominal System • AR systems are complex and involve not only illumination optics but also imaging optics as well as ergonomic considerations • It is usual to lay the system out in LightTools using idealized gratings in order to explore the system Light Guide Plate more e
Slide 11: The Importance of the Eye Box
The Importance of the Eye Box • For wearable optical systems, the designer must make accommodations for variances in human size and usage – Specifically, the inter-ocular distance can vary significantly with each user – The device may also be worn at a different height with respect to the eye from u
Slide 12: Eye Box Results for Our Nominal System
Eye Box Results for Our Nominal System • Here we see a false color illuminance map of our eye box – The eye box shows some complex structure due to the multiple bounces and extraction events on input and exit grids – However, the image rays are uniformly represented across the eye box as we shall se
Slide 13: Image Quality
Image Quality • The imaging system is designed to put the virtual image at an infinite distance from the eye – Collimated light – The system can be designed for a different virtual image distance, something closer to the user (diverging light), but care should be taken to avoid converging light at t
Slide 14: Imaging Quality at Different Eye Positions
Imaging Quality at Different Eye Positions • Here we show the imaging quality at different eye positions – What we are looking for is variations in illuminance for different parts of the image (e.g. some parts may disappear) – We have removed the dots and lowered the resolution 3mm Left Nominal 3mm
Slide 15: Designing Gratings
Designing Gratings • Once the nominal system has been developed and the designer is satisfied with the performance the ideal gratings must be converted to actual gratings • For this we use the RSoft Device suite to design actual gratings as near to the nominal specifications as possible • Once desig
Slide 16: Design Case 1: Structure Overview
Design Case 1: Structure Overview Left In-coupler Right In-coupler Reflection Type Transmission Type Out-coupling Out-coupling • Diffractive slanted gratings are • The slanted gratings can be • Two types of slanted gratings manufactured onto a high optimized to have high 1st order for out-coupler. T
Slide 17: Using DiffractMOD for Grating Design
Using DiffractMOD for Grating Design Index Profile A • Grating Properties: P – Wavelength: 0.52 µm – Period: 0.405 µm H R – H: grating height L – A: slant angle – L: Left slope angle Diffraction vs wavelength for from slant axis different orders – R: right slope angle from slant axis – Fill: duty ra
Slide 18: Grating Performance
Grating Performance • The charts below show the spectral bandwidth of the designed grating for the -1 through +1 orders (Reflected) as well as the diffraction efficiency as a function of angle – The angular bandwidth will limit the field of view of the projected image Spectral Angular Bandwidth Band
Slide 19: Diffraction Efficiency as a Function of Rib Height
Diffraction Efficiency as a Function of Rib Height • The plot below shows that the rib length can be used to vary the diffraction efficiency of the +1 order • Because this is an effective parameter, we will use this to optimize the gratings to create a uniform output across the eye box © 2020 Synops
Slide 20: RSoft BSDF Calculation for Optimal Structure
RSoft BSDF Calculation for Optimal Structure • Angular range of RSoft BSDF file: – Phi (from normal): Range of [0,90] with 1° spacing – Theta (around normal): Range of [0,360] since the structure is anisotropic with 5° spacing • BSDF Utility runs DiffractMOD simulations and both polarizations are au
Slide 21: Parametric BSDF Database
Parametric BSDF Database RSoft BSDF Generation Utility with FullWAVE FDTD or DiffractMOD RCWA • In BSDF Generation Utility, parametric BSDF data is supported – Any variables defined in RSoft CAD can be selected – Multi-variables parametric BSDF is supported as well © 2020 Synopsys, Inc. 21
Slide 22: Using the BSDF File in LightTools
Using the BSDF File in LightTools • Once the BSDF data has been generated in RSoft, it is a simple matter to integrate the data into the LightTools Model • Simply create an optical property for each grating – Set the Type to User-Defined – Select the UDOP_RSoftBSDF.dll, installed with RSoft Design T
Slide 23: Parametric BSDF Database
Parametric BSDF Database • In the optical properties with RSoft UDOP interface, the parameters calculated in RSoft are shown as variables, which can be defined as variables in optimization © 2020 Synopsys, Inc. 23
Slide 24: Initial Results with RSoft Gratings
Initial Results with RSoft Gratings • Here we show the initial results from our previous system but using an initial grating design from RSoft – There are some differences in the eye box, and the image field is slightly less uniform horizontally – Also notice that the image intensity has dropped fro
Slide 25: Expanding the Eye Box
Expanding the Eye Box © 2020 Synopsys, Inc. 25
Slide 26: Optics Size
Optics Size • As you may have noticed in the previous example, the imaging optics are quite large with respect to the device as a whole – This is undesirable because of the bulky size and excess weight – Driven by the field size and the need for the exit pupil to be a considerable distance in front
Slide 27: Beam Expander Example
Beam Expander Example • In this figure, DOE2 and DOE3 are DOE3 - Output shown as continuous regions • You can see that the output from DOE3 is far from uniform • To address this, we will sub-divide DOE2 and DOE3 into multiple zones and then use LightTools optimization to obtain a uniform output • Th
Slide 28: Ray Trace in LightTools
Ray Trace in LightTools • Here we see the ray trace of the demonstration system • DOEs 2 and 3 have not yet been sub-divided into zones Note the strong non-uniformity of the DOE3 output © 2020 Synopsys, Inc. 28
Slide 29: Sub-divide the Grating Zones
Sub-divide the Grating Zones • DOE2 and DOE3 are now sub-divided into 5 zones each • Each zone has its own optical property • Each grating property can then be optimized DOE3 DOE1 separately • To maximize the efficiency of the optimization the DOE2 was optimized first with the subzone furthest from
Slide 30: Optimizing Grating Rib Height
Optimizing Grating Rib Height • The grating rib height was optimized in LightTools using the standard optimizer – Parameter appears in the UDOP UI and can be made an independent variable for each zone optical property – A 5 x 5 output grid was used to optimize for uniform output Receiver grid used f
Slide 31: Optimized Result
Optimized Result • Here we see the emerging collimated spots at the eye box after optimization – Note the uniformity across the entire eye box © 2020 Synopsys, Inc. 31
Slide 32: Eye Boxes with Non-Collimated Source
Eye Boxes with Non-Collimated Source • We will now add an actual source and collimating optics and look at the eye box uniformity and image result • 8o projected grid pattern • Here we have put in a source with a field of view of +-4 • Backward ray trace to improve degrees ray trace efficiency – Thi
Slide 33: Thinning Down the Plate
Thinning Down the Plate • The original DOE spacing and plate thickness was chosen to give one ray bundle transmission per grating zone on the output grating – For a total of 25 exiting ray bundles • By thinning the plate down from 1.667mm to 1mm and adjusting the DOE spacing and size parameters then
Slide 34: Conclusion
Conclusion © 2020 Synopsys, Inc. 34
Slide 35: Conclusion
Conclusion • Augmented Reality and Virtual Reality systems are complex devices requiring careful design of the imaging, illumination and photonics portions of the system • All of these aspects need to work together • Synopsys Optical Solutions Group along with Photonics Optical Solutions Group provi
Slide 36: Thank You
Synopsys’ Silicon to Soft Thank You