Range-based focus assistance for projection optics

An apparatus, comprising:

• an optical assembly to project a light beam generated with a first light source onto a projection surface, the optical assembly being movable with respect to the projection surface and including at least one movable optical element;
• a distance-measurement device configured to provide a measure of a distance between the optical assembly and the projection surface, the distance-measurement device being movable together with the optical assembly;
• and
• a control circuit configured to determine a focus parameter value for the optical assembly based on the measure and further based on a present parameter value of the optical assembly,
• wherein the distance-measurement device and the optical assembly are translatable together with respect to the projection surface.

A method of providing focus assistance for a lighting fixture, the method comprising:

• obtaining, with an electronic processor, a present parameter value of an optical assembly included in the lighting fixture, the optical assembly including at least one movable optical element;
• obtaining, with the electronic processor, a measure of a distance between the lighting fixture and a projection surface, the measure being received from a distance-measurement device, wherein the distance-measurement device and the optical assembly are translatable together with respect to the projection surface;
• determining, with the electronic processor, a focus parameter value of the at least one movable optical element of the optical assembly, the focus parameter value being determined based on the measure and further based on the present parameter value;
• and
• controlling, with the electronic processor, a motor configured to move the at least one movable optical element to place the at least one movable optical element into a position corresponding to the focus parameter value.