Abstract
Abstract Information projection using laser-based illumination systems in the automotive area is of keen interest to enhance communication between road users. Numerous work on laser-based front end projection employing refractive and reflective optics has been reported so far, while for rear end illumination efforts are more scarce and a different optical design concept due to limited volumetric size and field of view regulations is required. Here, we report on a new and versatile approach for a laser-based rear end lighting system for automotive application which enables projection of information or signals to support other road users. The design is based on thin diffractive optical elements projecting the desired patterns upon illumination. Also, for protection of the road users from the steering laser beam, a diffusive back projection screen is designed to project information while fulfilling both the field of view and safety requirements. The projection system is based on a periodic diffusive structure made of an array of biconic lenses with sizes in the millimeter range. The field of view (FOV) from the simulated lens arrays complies with the angular requirements set by the Economic Commission for Europe (ECE). As a proof of concept, the diffusive screen is fabricated using microfabrication technology and characterized. In future, the screen will be combined with thin diffractive optical elements to realize an entire integrated projection system.
Highlights
Information projection for communication between road users is highly relevant in automotive [1,2]
We have presented a new and versatile approach for a diffractive optics based rear end automotive lighting system
The approach is based on diffractive optical elements (DOEs) which diffract the incoming laser light in multiple diffraction orders forming a defined pattern
Summary
Information projection for communication between road users is highly relevant in automotive [1,2]. The use of maskless photolithography systems enables faster and low-cost fabrication of microstructures on polymers For this purpose, a spatial light modulator (SLM) is used to project the desired microstructure patterns into a photoresist material. As for rear end laser-based lighting systems, the information is projected onto the outer lens of the optical system, which increases the laser exposure risk for other road users in case of failure. In a laser-based rear end lighting system, a nontransparent or partially transparent, i.e. a diffusive, outer lens is required The function of this element is to diffuse the steering laser beam and display the desired pattern on its outer surface. For proof of concept the required diffusive outer lens is designed and simulated in Zemax and manufactured using 3D printing
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