Design and implementation of a lightweight hybrid optical system for aircraft head-up display

The optimization of weight and volume of each component of aircraft, including mechanical, electronics and optical systems is crucial aspect. The cockpit of aircraft is loaded with different opto-mechanical, opto-electronics payloads such as head-up display (HUD), Head-Down Display (HDD) Multi-Function Display (MFD) etc. to assist the pilot. HUD is a critical payload of an aircraft which is designed using augmented reality and is being used since 4 decades. This HUDs realised with bulky optical systems having monochromatic cathode ray tubes (CRTs) of 543 nm wave length P-1, P-43, P-53 phosphors with a contrast ratio of 1.2:1 display source. CRT needs high power and specialized electronics to trace the synthetic display on CRT screen to the pilot. All this results in a lot of challenges w.r.t. weight, volume, and electromagnetic interference (EMI)/electromagnetic compatibility (EMC) management. Upgrading the display source by replacing of CRT with a compact Digital Micro-Mirror Device (DMD) is a potential solution for these challenges. However, maintaining the existing opto-mechanical parameter of the system is a challenging task. This paper proposed a design solution for optical components for compact and lightweight HUD. A non-imaging optics is designed for LED source with 543 nm wavelength to give uniform distribution of light, and imaging optics is designed for DMD of resolution of 750 × 750 pixels, pixel size 10 um with aspect ratio 1:1, of 543 nm wavelength projects an image of same size of CRT screen, with Modulation Transform Function (MTF) 0.6 at 5ln/mm, distortion around 5%. A prototype has been developed based on an optimized opto-mechanical design to fulfil the engineering requirements of the HUD.