Optical Alignment

​Around 300 BC, the Greek mathematician Euclid defined basic rules for the propagation of light from objects to the eye, starting the field of geometrical optics. In the first century AD, it was realized that optical surfaces had to be carefully crafted in order to control light rays. However, it was not until the advent of the telescope and microscope in the early 1600’s, when it was realized that multiple lenses could be aligned well enough together to form more complex optical systems. Using a “tube” (now called a lens barrel) to house two lenses, the early telescopes were arguably the first example of passive optical alignment. Soon it was realized that the performance of the telescopes could be improved by adjusting the position between lenses while looking through the telescope at a star, and optical active alignment was born. Fast forward to today, the age of hand-held and wearable consumer electronic devices, and there is a renewed interest in optical alignment fueled by the unique challenges encountered when miniaturizing optical systems.