Optics is one of the oldest fields of human inquiry, the results of which are visible to a sizable fraction of the world's population on a daily basis. Micro-optics is a sub discipline that has been more the domain of scientists and engineers, yet is increasingly, if sometimes almost invisibly, encroaching on the public domain.

The reader may justifiably ask at the outset: How do we distinguish between the two? The physics for optics and micro-optics is identical: image formation is the same for a set of 200 μm diameter microlenses as it is for 20 cm diameter projection lenses, even if secondary effects, such as diffraction, may play more of a role in one than in the other.

Nevertheless, micro-optics has two distinguishing characteristics:

• the feature sizes of micro-optics, and in many cases the sizes of the components themselves, are small, typically in the micrometer to nanometer range; and

• micro-optical components are typically manufactured using highly parallel mass fabrication techniques derived from those used by the semiconductor industry.

It is primarily for the latter reason that the history of micro-optics is a relatively recent one, as it is strongly coupled to developments in semiconductor technology.

Historical outline

Present-day applications of micro-optics range from medicine to entertainment, and it interesting to see how we have arrived at this point.