High-precision biaxial optical extensometer using multiple rhombic prisms

Abstract

The invention discloses a high-precision biaxial optical extensometer utilizing multiple rhombic prisms. The high-precision biaxial optical extensometer comprises a digital camera, a telecentric lens,four rhombic prisms, a fixed flat plate, a tripod and a data processing device; the four rhombic prisms are fixed in the fixed flat plate and are respectively positioned in upper, lower, left and right directions, and are equidistantly arranged away from the central point of the fixed flat plate; target points on the surface of a measured sample is sequentially reflected twice and then is converged and enters into the telecentric lens; the telecentric lens performs imaging simultaneously to form a digital image; the digital camera shoots four target areas at the same time to obtain the digital image; and the data processing device comprises a correlation operation module and a post-processing module, obtains displacement information of the four target points along a measurement directionaccording to the received digital image, and obtains local uniform strain information by combining the distance information of the four target points. According to the extensometer of the invention, the implementation steps of bidirectional view field separation are simplified, the scale distance is amplified by multiple times, and the measurement precision of biaxial strain is greatly improved.

Description

technical field [0001] The invention relates to a high-precision biaxial optical extensometer using a plurality of rhomboid prisms, and belongs to the technical field of optical measurement and nondestructive testing. Background technique [0002] In order to obtain the two constants of the elastic modulus and Poisson's ratio of the material, the lateral and axial strains of the material must be accurately measured in the elastic range, that is, the two-way strain. At present, the most common testing methods are sticking right-angle strain rosettes and using biaxial electronic extensometers to obtain bidirectional strain. These methods need to be in direct contact with the tested sample during measurement, which is easy to cause damage to the sample, so it is not suitable for large deformation, especially It is the detection of flexible materials, which enables optical non-contact measurement methods to show their talents. The optical strain measurement method is mainly rep...

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Problems solved by technology

[0004] In order to solve the problems existing in the bidirectional strain measurement accuracy of the existing optical extensometers, the present invention aims to provide a high-precision biaxial optical extensometer using multiple rhomboidal prisms, and realizes bidirectional field of view separation by using four rhomboidal prisms technology, combined with a telecentric lens to form a high-precision two-way optical extensometer

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