Embodiments are directed to an optical spectrometry method, comprising: generating a sequence of 2D Hadamard masks along the time dimension, wherein each 2D Hadamard mask is arranged with a wavelength dimension and a coefficient dimension; detecting an optical signal from light transmitted through the sequence of 2D Hadamard masks; and reconstructing a spectrum to be detected by analyzing the optical signal, wherein each 2D Hadamard mask in the sequence of 2D Hadamard masks comprises a plurality of columns along the wavelength dimension, each column corresponding to a different Hadamard coefficient, and having different respective sequency values along the time dimension.