Briefly, in accordance with one or more embodiments, a thermally controlled optical filter comprises a frame coupled to an etalon where the frame includes a resistive thermal device disposed on the frame to obtain thermal measurements of the etalon during operation. The frame may be generally L-shaped or generally square-shaped. The frame may include a fillet that is generally planar, generally beveled or trapezoidal, or generally circular in shape. A heater may be additionally disposed on the frame. The etalon and frame subassembly may be bonded to a micro hot plate that is capable of heating the etalon to an operational temperature.