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A portable feedback opticoelectronic system for measuring the shape of large-format objects is presented. It is based on the projection of phase-shifted interference fringes on the measured surface with subsequent digital processing of the interference patterns. The density and orientation of the projected fringes are set by an adjustable Michelson's interferometer, utilizing a phase-shifting mirror with three-point suspension and low-voltage control (0-12 V). The opticoelectronic feedback determines the value of the phase steps and monitors the level of the tolerable vibration noise. The system also includes a measurement CCD camera with high resolution and a personal computer with the relevant software for the measurements. Laser light sources in the visible and near-JR region with a power of up to 10 W in continuous mode can be used. Narrow-band interference filters with high transmittance make possible measurements under normal, daylight illumination ofthe working premises. When powerful lasers are used (for example, 10 W CW Ar laser at 488 nm) the mirrors should have dielectric coatings. The interferometer is sealed and underpressure with an inert gas (Ar) is maintained in it in order to protect the optical elements against dust, burning and coherent noise. A description is made of the design, operating procedures, theoretical background and experimental results from measurements of real objects in working conditions.

The topic of computer recognition and entry of alpha-numeric information has been known for approximately 30 years. Today, it is still vital, because the problems related to it have not found satisfactory solution. For example, the existing automatic reading devices require special fonts, like OCR -A, OCR -B, CMC -7, E13B, etc.The complete solution of the problem demands a reading system, capable of inputting letters, signs, numerals of arbitrary fonts and height from manuscripts and books. This problem is very complex and very hard to solve. A step towards finding a more general solution is the proposed factorization method for preliminary processing of printed text to be entered in a computer. It makes possible the recognition of letters and signs of different fonts and sizes.Basically, automatic reading devices include an optoelectronic transducer (scanner) and a computer for processing the electric signals. It is known that the higher the resolution of the scanner, the more reliable is the recognition. On the other hand, the necessary capacity of the memory increases with the second power of the resolution. However, the use of special algorithms and preliminary information processing can facilitate to a great extent the process of recognition. The algorithm of the factorization method helps compress and extract the essential initial information for computer recognition, thus reducing the capacity of the needed memory.

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