Design of an efficient Fresnel-type lens utilizing double total internal reflection for solar energy collection.

A novel of Fresnel-type lens for use as a solar collector has been designed which utilizes double total internal reflection (D-TIR) to optimize collection efficiency for high numerical aperture lenses (in the region of 0.3 to 0.6 NA). Results show that, depending on the numerical aperture and the size of the receiver, a collection efficiency theoretical improvement on the order of 20% can be expected with this new design compared with that of a conventional Fresnel lens.

Designing a laser scanning picoprojector. Part 2: laser-safety-related issues.

Laser scanning picoprojectors present a new challenge in the field of laser safety with methods of calculating accessible emission limits still in their infancy. We present a laser safety analysis and a calculation of an example picoprojector. We show that, due to its scanning operation, a picoprojector should be considered an extended laser source, and we also show that a picoprojector with two separate one-axis microelectromechanical systems mirrors offers a higher safe power limit than a projector with a single scanning mirror. Finally, a safety analysis is done under conditions of mirror failure. We show that, if the projector fails to scan in just one of the axes, the ocular hazard rises sharply, highlighting the need for a fail-safe system to be built into laser scanning picoprojectors.

Designing a laser scanning picoprojector. Part 1: characteristics of the optical displaying system and color-management-related issues.

When designing a laser scanning picoprojector, one has to deal with important aspects that do not strictly involve design of hardware and software. We have identified two issues that play a decisive role in the final specifications of a laser scanning picoprojector: the characteristics of the optical displaying system and color management. Regarding the optical system, we have studied the diameter requirements of the laser beam emitted from a picoprojector from the point of view of image quality. Resolution is assessed by calculating the image modulation produced by a projected laser spot over a range of projection distances and image sizes. We also show that a suitable election of the RGB wavelengths increases the lumens-per-watt ratio and thereby improves efficiency of a laser-based picoprojector.

Design of an efficient Fresnel-type lens utilizing double total internal reflection for solar energy collection.

A novel of Fresnel-type lens for use as a solar collector has been designed which utilizes double total internal reflection (D-TIR) to optimize collection efficiency for high numerical aperture lenses (in the region of 0.3 to 0.6 NA). Results show that, depending on the numerical aperture and the size of the receiver, a collection efficiency theoretical improvement on the order of 20% can be expected with this new design compared with that of a conventional Fresnel lens.