Abstract: A modular interchangeable laser instrumentation system for applications in industrial processing, medical surgery and treatment, dental treatment, metrology, military applications, forensic investigation, micromachining, optical storage, spectroscopy, research and many other related applications. The system principally comprises a handheld stylus with interchangeable modules to produce various selected laser-radiation beams for any particular work as needed. Each module and the combined modular stylus is adapted to produce a particular type of laser beam for the intended project in hand, and as the modular section of one stylus is replaced by the modular section of another stylus, the generated laser beam assumes a different optical and spectral character, so as to be compatible with the work under process and characterized by the type of material and thickness thereof, texture, or human anatomical tissue of one kind or another, requiring different focus intensities and modal formats.