A hybrid fresnel lens for a virtual reality lens is shown below. For a VR/HMD application, it is important to maximize performance while minimizing the number of optics to save weight and cost.
Q sight and Scorpion are two example of military HMDs using waveguide technology. Diffractive elements are used to couple light from a projector into a waveguide which relays the image to the eye. This type of HMD provides a low profile design while giving the user see through capabilities.
Hybrid fresnel lens for Virtual Reality HMD.
Optical Engineering & Analysis LLC
The free from prism is a catadioptric lens created from a single piece of plastic. These are designed for Head Mounted Display applications. These lenses are designed to save space and weight compared to existing complex lens systems. The use of a compensating lens allows the prism to be see through.
Simulatd image as seen by the user.