An imaging spectrometer is disclosed that comprises imaging means for dividing a received image into two or more spatially separated images and means for detecting each spectral image, and is characterized in that the imaging means comprises at least one polarizing beam splitter. The polarizing beam splitter may be a Wollaston prism. In one embodiment of the invention, the imaging means comprises image replication means to produce two or more spatially separated images, and one or more filter elements such as dichroic filters which act to alter the spectral characteristics of one or more of the spatially separated images. In a further embodiment of the invention the imaging means comprises one or more spectral replication means arranged in optical series, each spectral replication means comprising an optical retardation element and a polarizing beam splitter.