The author studied technical physics at the Technical University of Delft, the Netherlands. He obtained a masters degree in 1965 with a thesis on the fabrication of lasers. After military service he found a position with Philips Electronics of Eindhoven, where he joined projects in holography, spectroscopy, optical recording and semiconductor laser research. He obtained a doctor’s degree from the University of Utrecht with a thesis on Fourier spectroscopy (1974). In the second half of his Philips career (1982-1997) he was a consultant in industrial metrology. Dr. Velzel left Philips in 1997 to join the company Nano Focus (Oberhausen, Germany), of which he is a co-founder. After seven years with Nano Focus, where he assisted in the development of confocal microscopes for surface characterisation, he started a new career as a teacher and consultant in optics, which he follows until the present day. Dr. Velzel is co-author of the book “What Is Light”, with his teacher Prof. A.C.S. van Heel and of many other publications and patents. He served on the International Commission for Optics as a vice-president (for industry) from 1986-1992.