An optical spectroscopy diagnostic has been designed to observe emissions from the nonthermal alpha particle population that will be generated during the D–T operation phase on TFTR. The system will observe spectral line emission near 469 nm from the slowing‐down alpha population interacting with the heating neutral beams through charge exchange. The required spectrometer throughput and resolution are obtained by modification of a simple commercial spectrometer system, while a series of measurements indicate that a cooled CCD array is usable as a high‐efficiency detector with photon‐noise‐limited accuracy to roughly a part in 104.