An apparatus comprising: a spectral filter that is operative for receiving a first light signal characterized by a first spectral range and providing a second light signal that is spectrally dispersed along a first direction, the x-direction, wherein the second light signal is characterized by a second spectral range within the first spectral range, and wherein the spectral filter includes: (i) a first mirror that is planar and partially transmissive for the first light signal; (ii) a second mirror that is planar and partially transmissive for the first light signal, wherein the first mirror and second mirror define an optically resonant cavity having a cavity length that is controllable along the first direction; and (iii) a first actuator that is configured to control a first separation between the first mirror and second mirror at a first location, wherein a first angle (θ) of the first mirror relative to the second mirror along the first direction is based on the first separation; wherein the second spectral range has a first spectral width that is based on the first angle; a light source for providing the first light signal to the spectral filter such that the spectral filter receives the first light signal along a third direction, the z-direction, that is orthogonal to the first direction, the x-direction; and a detector array that includes a plurality of detectors (110-1 to 110-m), wherein the detector array is arranged to receive the second light signal from the spectral filter such that each detector of the plurality thereof receives a different wavelength signal of a plurality of wavelength signals that are characterized by different wavelengths within the second spectral range; characterized in that the spectral filter is configured such that, when the spectral filter is in a quiescent state, each of the first mirror and second mirror is oriented at a second angle (α) relative to the third direction, and wherein the second angle (α) is not equal to 90°, and wherein the second angle (α) is selected to improve the quality factor Q of the cavity. a spectral filter that is operative for receiving a first light signal characterized by a first spectral range and providing a second light signal that is spectrally dispersed along a first direction, the x-direction, wherein the second light signal is characterized by a second spectral range within the first spectral range, and wherein the spectral filter includes: (i) a first mirror that is planar and partially transmissive for the first light signal; (ii) a second mirror that is planar and partially transmissive for the first light signal, wherein the first mirror and second mirror define an optically resonant cavity having a cavity length that is controllable along the first direction; and (iii) a first actuator that is configured to control a first separation between the first mirror and second mirror at a first location, wherein a first angle (θ) of the first mirror relative to the second mirror along the first direction is based on the first separation; wherein the second spectral range has a first spectral width that is based on the first angle; (i) a first mirror that is planar and partially transmissive for the first light signal; (ii) a second mirror that is planar and partially transmissive for the first light signal, wherein the first mirror and second mirror define an optically resonant cavity having a cavity length that is controllable along the first direction; and (iii) a first actuator that is configured to control a first separation between the first mirror and second mirror at a first location, wherein a first angle (θ) of the first mirror relative to the second mirror along the first direction is based on the first separation; a light source for providing the first light signal to the spectral filter such that the spectral filter receives the first light signal along a third direction, the z-direction, that is orthogonal to the first direction, the x-direction; and a detector array that includes a plurality of detectors (110-1 to 110-m), wherein the detector array is arranged to receive the second light signal from the spectral filter such that each detector of the plurality thereof receives a different wavelength signal of a plurality of wavelength signals that are characterized by different wavelengths within the second spectral range; characterized in that the spectral filter is configured such that, when the spectral filter is in a quiescent state, each of the first mirror and second mirror is oriented at a second angle (α) relative to the third direction, and wherein the second angle (α) is not equal to 90°, and wherein the second angle (α) is selected to improve the quality factor Q of the cavity.