An atomic absorption spectrometer which combines the advantages of double beam background correction, continuous source lamp operation, insensitivity to sample region emission, and inexpensive construction, includes a fixed beam splittercombiner, combines radiation from a line source with that from a deuterium or hydrogen source and simultaneously splits the combined radiation into sample and reference beams. These beams are chopped ahead of the sample region and are recombined beyond the sample region by a second beam splitter-combiner. The recombined beam then goes through a monochromator and onto a detector. The resulting signal is analyzed electronically to yield background and spectral line intensities in both the sample and reference beams.