Optics in Instruments

Chapter 7

Optics for Imaging: Definition, Manufacturing, Applications ¹

Optics for imaging means optical devices used in photographic instruments, cinema or television cameras, telescopes, microscopes, etc. All use devices based on opto-mechanics, which in this case we call “lenses”. They form “real” images by converging beams of light coming from an observed object toward the sensor, which may be an argentic film or a digital sensor, which performs the imaging process.

7.1. Lenses for photography

To create a photographic image, a lens which has the basic characteristics of an aperture, an object field of view and spatial resolution, is needed, as it allows us to obtain a real image of an object which is as large, bright and sharp as possible. This could not be done by a small hole in an opaque screen — a device known as a pinhole camera, also capable of producing an image which is usable in certain conditions, for certain requirements.

At the other extreme of complexity, certain measures are being considered today to obtain images without using classic objectives. These measures, instead, use a technique that analyzes the wave front surfaces coming from sources in the field of observation; overlooking convergence factors, they constitute the components of an intermediary virtual image transformable by mathematical calculation into a real image. This technique is the subject of advanced studies and does not yet enter into our field.

The most widespread geometrical image formats ...