When the IAS project ended in 1956, he joined Bell Laboratories where he worked on human perception, computer vision and graphics.
In 1966, Harmon and Kenneth C. Knowlton were experimenting with photomosaic, creating large prints from collections of small symbols or images.
In Studies in Perception I they created an image of a reclining nude (the dancer Deborah Hay), by scanning a photograph with a camera and converting the analog voltages to binary numbers which were assigned typographic symbols based on halftone densities.
In 1976, Salvador Dalí used Harmon's image as the basis of his Gala Contemplating the Mediterranean Sea and Lincoln in Dalivision.
He supervised one graduate student, Thomas F. Collura, who received his Ph.D. in 1978 for studying brainwave (EEG) signatures of attention in human subjects, using an analog computer.