February 2000

The Scientific Life of the Camera Obscura

Brian S. Baigrie

By the time the first photographic experiments were taking place at the beginning of the nineteenth century, the camera obscura had evolved into three distinct forms. One was a darkened room with a lens and mirror in the roof. Furnished with improved lenses that could cast larger and sharper images, this type of camera obscura, which flourished at seaside resorts and other picturesque sites, produced an image on a table.

Machine Vision: Optical Digitization of Free-Form, Complex Surfaces Using the Projection of Structured Light

The use of optical sensors to evaluate threedimensional shapes plays an increasingly important role in a number of applications. One important advantage of optical sensors is that no contact is required with the object being measured; another is that they are significantly faster than contact probes. Typical industrial applications for optical sensors are production quality control, both in the micro and the macro ranges, the digitization of freeshape surfaces in reverse engineering, and a number of 3-D computer vision problems. Examples of the latter are object manipulation by means of robots and obstacle detection for robotic vehicles. New areas in which optical sensors have been successfully introduced include the measurement and preservation of antiquities, and 3-D virtual reality entertainment products.

Auto Industry Embraces Optical Technologies

The Auto Industry is an enormous proving ground for technological advances, exceeded only by the defense and aerospace industries. These advances have chiefly been in the areas of metallurgy, electronics and emission controls, all of which have had to meet the rigid cost constraints of the automobile industry. Historically, the use of optical devices—other than mirrors and focusing lenses for lamps—has been limited. Exceptions include optical fiber (as lamp monitors on late-60s Corvettes and Cadillacs), photocells (as headlamp dimming switches in the late 1950s) and IR sensors (principally as back-up warning systems for trucks). Until very recently, in fact, the auto industry’s cost constraints have precluded the use of optical devices. Now, however, the situation is rapidly changing. Several new optical-based products are already (or will soon be) available as factory-installed or aftermarket equipment. Two particularly significant technologies are “smart glass” and night vision systems.


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