A sensor for measurement of an analyte in a medium within a living animal, the sensor comprising: a first photodetector configured to convert received light into current indicative of the intensity of the received light; a second photodetector configured to convert received light into current indicative of the intensity of the light received by the second photodetector; an analyte indicator configured to emit emission light; a light source configured to irradiate excitation light to the analyte indicator; a rigid and biocompatible sensor housing; a first low angle sensitive, LAS, optical filter that utilizes dichroic and absorptive filtering and is configured to prevent light having a wavelength outside a first band pass region from reaching the first photodetector and to pass light having a wavelength within the first band pass region to the photodetector, wherein the first low angle sensitive optical filter is configured such that the percentage of light passing through the first LAS optical filter decreases as the angle of incidence of the light on the first LAS optical filter increases, and the first band pass region includes the wavelength of the emission light; wherein the emission light is emitted at least to the first LAS optical filter; and a second LAS optical filter that utilizes dichroic and absorptive filtering and is configured to prevent light having a wavelength outside a second band pass region from reaching the second photodetector and to pass light having a wavelength within the second band pass region to the second photodetector, wherein the second low angle sensitive optical filter is configured such that the percentage of light passing through the second LAS optical filter decreases as the angle of incidence of the light on the second LAS optical filter increases, and the second band pass region includes the wavelength of the excitation light; wherein the sensor is configured to be implanted in the living animal and to wirelessly communicate with an external transceiver via an inductive magnetic link; and wherein the analyte indicator is a polymer graft coated, diffused, adhered, or embedded on or in at least a portion of an exterior surface of the sensor housing, and the analyte indicator comprises indicator molecules configured to emit an amount of the emission light based on the amount or concentration of the analyte in proximity to the analyte indicator. a first photodetector configured to convert received light into current indicative of the intensity of the received light; a second photodetector configured to convert received light into current indicative of the intensity of the light received by the second photodetector; an analyte indicator configured to emit emission light; a light source configured to irradiate excitation light to the analyte indicator; a rigid and biocompatible sensor housing; a first low angle sensitive, LAS, optical filter that utilizes dichroic and absorptive filtering and is configured to prevent light having a wavelength outside a first band pass region from reaching the first photodetector and to pass light having a wavelength within the first band pass region to the photodetector, wherein the first low angle sensitive optical filter is configured such that the percentage of light passing through the first LAS optical filter decreases as the angle of incidence of the light on the first LAS optical filter increases, and the first band pass region includes the wavelength of the emission light; wherein the emission light is emitted at least to the first LAS optical filter; and a second LAS optical filter that utilizes dichroic and absorptive filtering and is configured to prevent light having a wavelength outside a second band pass region from reaching the second photodetector and to pass light having a wavelength within the second band pass region to the second photodetector, wherein the second low angle sensitive optical filter is configured such that the percentage of light passing through the second LAS optical filter decreases as the angle of incidence of the light on the second LAS optical filter increases, and the second band pass region includes the wavelength of the excitation light; wherein the sensor is configured to be implanted in the living animal and to wirelessly communicate with an external transceiver via an inductive magnetic link; and wherein the analyte indicator is a polymer graft coated, diffused, adhered, or embedded on or in at least a portion of an exterior surface of the sensor housing, and the analyte indicator comprises indicator molecules configured to emit an amount of the emission light based on the amount or concentration of the analyte in proximity to the analyte indicator.