We report a simplified optical heterodyne detected transient grating setup consisting of a single diffractive optical element based on modifications of the arrangement used by Miller and co-workers [J. Phys. Chem. A, 103 (1999) 10619]. Our arrangement features ease of alignment, suppression of scattering and is free of pump-probe contamination in the detected transient grating signals. The capability of our arrangement is demonstrated by measurements on a nonresonant system, CS2, and a resonant system, malachite green in ethanol.