An optical spectrometer with a tilted or brazed optical grating is useful to identify material composition, estimate physical characteristics, and measure physical conditions. Light from a sample or a space reflects to the grating; and stray light from the grating directed on an optical sensor (which can be a single sensor) and converted into an electrical signal, to obtain information about the sample or space. Examples of scanning include altering an angle the light strays from the optical grating by applying a strain to the optical grating, moving the optical sensor, and installing a mirror in the path of the stray light that reciprocatingly pivots over an angular range. In an example, the optical grating is formed on a light transmission medium that mounts to a piezoelectric element, that expands when energized to apply strain to the grating. In an example, the diffraction grating is a Fiber Bragg Grating.