Elimination of ghost image in expanded viewing angle head-up display systems

Wide field of view flat-panel head-up display system

“…For the elimination of the ghost image and ensuring the usability with polarized sunglasses, we investigated a polarization-based method that works on an expanded FOV 16 , 17 . The most appropriate method for a flat-panel HUD is the application of a windscreen tilted near Brewster’s angle (57 deg for glass) and coated with a reflective film having a reflectivity around 20% for the p-polarized visible light.…”

“…We inserted this shape into our previously developed model 16 , 17 and calculated the intensity ratio of the ghost image and the primary image as the function of the αH horizontal and αV vertical viewing angles. The windscreen consisted a glass-PVB-glass stack (with thicknesses of 2.1, 0.6, and 2.1 mm, respectively) and one of its inner surfaces was coated with a thinfilm designed for 70% transparenecy of perpendicular light, and 20% reflectivity of P-polarized light incident in 57 deg.…”

“…The distortion of the curved windshield was digitally corrected in the displayed image. The suppression of the ghost image with a spatially variant birefringent halfwave plate is discussed in our previous articles, 16 , 17 but the application of spatially variant polarizer has not been published until now. The photo shows that the ghost image has been successfully eliminated with this method too.…”

“…For the elimination of the ghost image and ensuring the usability with polarized sunglasses, we investigated a polarization-based method that works on an expanded FOV. 16,17 The most appropriate method for a flat-panel HUD is the application of a windscreen tilted near Brewster's angle (57 deg for glass) and coated with a reflective film having a reflectivity around 20% for the p-polarized visible light. The display is equipped with a spatially variable polarizer sheet to modify the emitted polarization of the LCD screen to an optimal polarization configuration to minimize the ghost image intensity.…”

Recent Advances in Light Detection and Ranging: Optical Modulation Solutions and Novel Nanotechnologies

“…Types Solution References mutual interference pulsed ToF random pulse trains [35] generate random sequence of double pulses by binary chaos generator [42] constitute CPPM by algorithm to generate random sequence [33] generate random signal sequence by LED+CMOS SPAD [36,[54][55][56] develop a multi-pulse detection algorithm [57] FMCW the interference signal can be extracted from the low-pass filter with wavelet denoising [58] few-mode frequency-modulated LiDAR receivers [40] frequency-Hopping modulator [39] RMCW use ASE laser to generate chaos signals [41] random signals generated by external optical perturbation [43][44][45][46][47][48][49] ghost image optic rotate the angle of the polarizing beam splitter to reduce the reflections of mirrors [52] adjust optical polarization to defocus unwanted stray light reflections [59][60][61] add anti-reflection mode and filter to suppress ghost reflection [62] enhance self-heterodyne synthetic aperture Imaging radar (Coherent Radar Architecture) [63] a higher gain length and a more powerful output from a single diode. However, the active region's vertical thickness is small compared to the horizontal width due to the designed geometry, producing an asymmetric elliptical beam profile rather than an ideal circular Gaussian beam.…”