Patent ID: 8059327

Claim:
A variable spectral filter apparatus comprising: a filter support that is rotatable about a single axis of rotation and that comprises at least first and second transmissive spectral filters, each spectral filter having a filter width defined by its first and second edges, wherein the filter width is in a direction that is orthogonal to the single axis of rotation, wherein the first edges of the at least first and second transmissive spectral filters are substantially equidistant from the single axis of rotation when the filter support is rotated to any angle, and wherein the plane of each of the at least first and second transmissive spectral filters is substantially parallel to the single axis of rotation, wherein rotational positions of the filter support about the single axis of rotation, over a first 60 degree range of angles, define, between the first and second edges of at least the first spectral filter, an undeviated filtered light path of at least about half the filter width, wherein the filtered light path extends orthogonally with respect to the single axis of rotation; and a rotational actuator energizable to rotate the filter support about the single axis of rotation.