Abstract: A method of estimating non-linearity in a response of an optical detector comprises emitting optical radiation at different intensities. The method includes, at each intensity: amplitude modulating the emitted optical radiation at a modulating frequency to produce amplitude modulated optical radiation; detecting the amplitude modulated optical radiation with the optical detector to produce a detected waveform; and generating a Fourier transform of the detected waveform that includes a fundamental frequency equal to the modulating frequency and harmonics thereof. The method further includes estimating the non-linearity in the response of the optical detector based on a change in an amplitude of a second harmonic of the fundamental frequency relative to an amplitude of the fundamental frequency across the Fourier transforms corresponding to the different intensities.

Abstract: A device for calibrating a sensor using solar radiation includes a sensor configured to measure electromagnetic radiation received through a field of view (FOV) having a normal line of sight and at least two baffles removably insertable across the FOV of the sensor and inclined to the line of sight. Each baffle has first and second opposing surfaces, with the first surface disposed to face the solar radiation and the second surface disposed to face the sensor. One of the first or second surface is configured as a diffused surface, and the other of the first or second surface is configured as a specular surface.

Abstract: A solar calibration device for a remote sensor having a housing having a deployable door at one portion of the housing and an aperture at another portion of the housing is provided. Disposed in the housing is a solar diffuser for receiving solar irradiance when the deployable door is in an open position, and diffusely reflecting the received solar irradiance. A solar diffuser monitor also disposed within the housing receives diffusely reflected solar irradiance from the solar diffuser, for calibrating the solar irradiance reflected from the solar diffuser, and receives solar irradiance directly from the sun through the aperture to calibrate the spectral reflectance of the solar diffuser monitor detectors based on the solar irradiance received directly from the sun.