From the earliest days of humanity, when we gazed upon the midnight heavens ablaze with the twinkling fire of the stars, humans have been fascinated by light. We need no more proof of this than the fact that most of us centre our daily activities around the segment of time that the sun shines its warmth upon us, or that our pastimes are so dependent upon this wondrous phenomenon. Early civilizations actually worshipped light, or rather, the sun -- but if there ever was anything worthy of worship, it is certainly light, for without light, the delicate balance of life on this earth would be broken. Plants require the sun's nourishing energy to grow; in turn more mobile creatures are dependant upon these plants for sustenance. If the sun did not radiate upon our earth, our planet would be a cold, barren, lifeless rock.
Optics, the study of light, dates back to Euclid. He stated that light travels in straight lines, and thought, peculiarly (at least from our modern perspective), that sight came about from rays that moved from the eye to the object being observed. Euclid was also aware of the Law of Reflection. As early as 140 A.D., the Greeks were aware that light bends when it moves from one medium to another. The first mention of using lenses as a correction to defects in sight is attributed to the scientist Roger Bacon, of 13th century London. The microscope was invented in 1590, and famed Galileo constructed the first telescope soon after, in 1609. With these two new instruments, the study of biology, chemistry, and physics would advance in leaps and bounds.
Today, we are utilising the principles of optics to improve communication speeds (fibre optic cables) and compter storage (CD-ROMs and their offspring). Tomorrow, perhaps, we will trace the paths of those omnipresent visitors from the night sky, and avail ourselves of the hospitalities of their abodes.
The goal of this project is to give the reader a basic presentation of the way that light behaves when it interacts with optical systems consisting of mirrors and lenses. We do not assume any prior knowledge of physics; we only require a basic understanding of Euclidean plane geometry, and a smidgen of calculus. With a few approximations, the basic principles of mirrors and lenses are surprisingly simple to understand.