Microfiche

Microfiche is one of the most compact analog storage media in common use. It is normally used to provide a comprehensive research library in institutions (such as small college libraries) that could not otherwise afford the floor space. A library of 20,000 books, one per fiche, fits in a cabinet about 1.5x0.5x2 meters. Some companies specialize in providing such libraries to institutions.

Microfiche is normally used to keep copies of books, and sometimes for periodicals. Its most standard form is a clear plastic card, about 10cm (4in) by 15cm (6in). Usually the title of the work is in visible lettering along one edge. The closely-spaced dots are each one page of the work. Some microfiche have a digital indexing system exposed on the edge of the card, or each image, but this data is not required to use the microfiche, but rather to support automated retrieval systems.

Microfiche is not the most widely used microform. Microfilm is more widely used.

The medium has numerous advantages. First, it is compact, with far smaller storage costs than paper documents. Generally, a book or a year of a periodical fits on one fiche and takes 0.05% of the space and weight of the paper work. Second, it is lower cost than a paper copy. Most microfiche services get a bulk discount on reproduction rights, and have lower reproduction costs than a comparable amount of printed paper ($5 per fiche in 2003). Third, it is a stable archival form. Most library microfiche use polyester with silver-halide dyes in hard gelatin, with an estimated life of 500 years in air-conditioning. In tropical climates with high humidities, fungus eats the gelatin used to hold silver-halide. In the tropics, diazo-based systems with lower archival lives (20 years) are preferable, because they have polyester or epoxy surfaces. Fourth, since it is analog (an actual image of the orginal data), it is easy to view. Unlike digital media, the data format is instantly comprehensible to persons literate in the language; the only additional equipment that is needed is a simple magnifying glass. This reduces the possibility of obsolescence.

The principal disadvantage of microfiche is that the image is too small to read. Libraries use special readers that project full-size images on a ground-glass screen. A significant disdvantage is that when stored in the highest-density drawers, it is easy to misfile a fiche, which is thereafter unavailable. Some libraries therefore keep the microfiche cabinet in a restricted area, and fetch fiches on demand. Some fiche services use lower-density drawers with labelled pockets for each card. Another disadvantage, is that a conventional photocopier cannot reproduce the images. Libraries using microfiche often have a few viewers that can produce a photocopy of an image, for a nominal fee. The final disadvantage is that microfiche can only be reproduced a limited number of times, while digital media regenerate and often include error detection and correction schemes.

Links

• The Library of Congress Photoduplication Service (http://www.loc.gov/preserv/pds/)
• The Northeast Document Conservation Center (http://www.nedcc.org/plam3/tleaf51.htm)