Light bulb with adjustable light output

A light bulb, comprising:

• a base configured to mechanically mount the light bulb and receive electrical power;
• a light source electrically coupled to the base;
• a light guide having opposed major surfaces, a light input edge, and a distal edge opposite the light input edge, wherein the light guide is coupled to the base and arranged to receive light from the light source at the light input edge, the light propagating along the light guide by total internal reflection, and at least some of the light is extracted from the light guide through at least one of the major surfaces, light not extracted through the at least one of the major surfaces incident on the distal edge, the distal edge comprising a first distal edge region through which incident light exits the light guide and a second distal edge region;
• and
• an optical adjuster having a surface juxtaposed with the distal edge of the light guide, the optical adjuster having a first adjuster region and a second adjuster region, at least the first adjuster region having a light modifying characteristic, the optical adjuster and the first distal edge region variably positionable relative to one another to selectively apportion light emitted from the first distal edge region between the first adjuster region and the second adjuster region, the light apportioned to the first adjuster region being modified by the light modifying characteristic thereof so that a characteristic of the light output from the light bulb is modified based on relative positioning of the optical adjuster and the first distal edge region.