Abstract: A multi-part sleeping bag for use in camping, backpacking, mountain climbing, and the like is disclosed. The sleeping bag comprises an elongated body having a bottom panel and a top panel, each panel having an outer surface and an inner surface and a peripheral edge connecting the surfaces. The sleeping bag includes at least one closure means extending along at least a closable portion of the peripheral edge of each panel, adapted to selectively fix the closable portion to each other, or to selectively enable separation of each panel from the other making the bag convenient for household washing machines. The panels are rectangular in shape in plan view or taper in reducing width from a head end to a foot end. Further, a second closure means on each panel mutually joins another sleeping bag forming a two person sleeping bag.

Abstract: A Variable Optical Attenuation Collimator (VOAC) is disclosed to achieve a variable degree of optical power attenuation through the collimator by adding an Attenuation Control Element (ACE) between a lens element and fiber pigtails of a traditional fiber optical collimator. The body of the ACE can be implemented in many different ways such as a polymer-network liquid crystal light scattering and absorbing material, a Refraction Index Gradient Controllable Material (RIGCM) capable of controllably swerving the direction of light propagation, a Refraction Index Controllable Material (RICM) capable of controllably defocusing an incident light power and a transparent Length Controllable Material (LCM) capable of controllably changing the spacing between the lens element and the fiber pigtails causing a defocusing of an incident light power.