by The Green Fairy

Created on: March 01, 2009

A scanner is a device which uses optical technology to capture a document and create a two-dimensional image which can be stored on a computer. They are widely used today in both commercial and domestic settings, and are used to create digital copies of photographs, documents and a range of other items. It possible to scan a three-dimensional item with a flatbed scanner, and this produces a two dimensional image of the object as viewed from the bed of the scanner.

The first image to be scanned was a photograph of three month old Walden Kirsch, captured in 1957 at the National Bureau of Standards (now the National Institute of Standards and Technoloyg or NIST). The picture was created by Russell Kirsch, the child's father, using a drum scanner.

The first scanners were drum copiers, capturing information with photomultiplier tubes. Items to be scanned are mounted on a cylinder which rotates, the drum, and this is passed in front of the optical equipment which captures the image. Drum scanners are still used, as they enable capture of very high quality images, up to 12,000 PPI and they are often used in film work. They are very expensive, ranging from tens of thousand of dollars to a hundred thousand.

In the 1990's small hand-held scanners were available. These were drawn across the page by the user and usually produced a monochrome image. These required a steady hand and movement at a consistent speed across the page.

The flatbed scanner, which became affordable later in the 1990's, reversed the process, with the optical reader placed under a sheet of glass, facing upwards, and items to be scanned were laid on the glass. They are able to capture colour images and the quality has improved dramatically over the last decade, and prices have fallen.

Most scanners incorporate the capability for optical character recognition, or OCR. This technology was first developed in the 1920's. However, it wasn't until the 1950's that the technology began to be used in earnest. In 1976 Ray Kurzweil unveiled the first device which could scan text and convert it into speech, making print accessible to the blind. His device included the first flatbed scanner.

It is not unusual to assume that photocopiers and scanners share a common history, as there is considerable similarity between them. Flatbed scanners and photocopiers both have a glass plate on which the subject is laid, and both create a copy which can be either digital or hardcopy. However, the similarity is not as close as it appears - early photocopiers were analog devices which only produced a hardcopy result, and a scanner only produces digital output. Photocopying technology was developed during the 1940's, with the first copier going on sale in 1949.

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