Holographic waveguide heads-up display for longitudinal image magnification and pupil expansion

Abstract

The field of view of traditional heads-up display systems is limited by the size of the projection optics. Our research is focused on overcoming this limitation by coupling image-bearing light into a waveguide using holographic elements, propagating the light through that waveguide, and extracting the light several times with additional holographic optical elements. With this configuration, we demonstrated both longitudinal magnification and pupil expansion of the heads-up display. We created a ray-trace model of the optical system to optimize the component parameters and implemented the solution in a prototype that demonstrates the merit of our approach. Longitudinal magnification is achieved by encoding optical power into the hologram injecting the light into the waveguide, while pupil expansion is obtained by expanding the size of the hologram extracting the light from the waveguide element. To ensure uniform intensity of the image, the diffraction efficiency of the extracting hologram is modulated according to the position. Our design has a 12°×8° field of view at a viewing distance of 10 in. (250 mm), with infinite longitudinal magnification and a 1.7× lateral pupil expansion.

With flying colours: Pilot performance with colour-coded head-up flight symbology

“…This results in the omission of information normally provided, or organised, by colour coding. However, recent advancements in waveguide optical technology means that the development of colour HUDs could be viable in the near future [23]. The display technology in HMDs is different and the development and design of colour displays has matured further in comparison to HUDs.…”

Improving head-up display with waveguides and holographic optical elements

“…Horizontal pupil expansion is achieved by encoding a variable DE across the length of the extraction so that the amount of light extracted from any point along the length of the waveguide is the same intensity. 23 Figs. 3 and 4 demonstrate front and isometric views of the system, respectively.…”

“…To address these issues, recent research has explored the use of diffractive optics and holographic optical elements (HOEs) to achieve image magnification and pupil expansion. [18][19][20][21][22][23][24] In these systems, a HOE couples light into a waveguide, where it propagates due to total internal reflection (TIR) until it interacts with other Light from the source is encoded with a relevant image by the imaging device. This image passes through the relay optics so that it is located in the far field.…”

Holography for automotive applications: from HUD to LIDAR

“…More recently, waveguide optics have been used to improve upon the traditional reflective holographic combiner. [17][18][19][20] The unique property of this system is that the light that travels inside the waveguide using the total internal reflection (TIR) condition can be recirculated and extracted several times. This mechanism increases the size of the pupil to offer a larger eye box.…”