Vic-3D Stereo Microscope

The Vic-3D Micro sys­tem is a new addi­tion to the Vic-3D prod­uct line of mea­sure­ment solu­tions. Vic-3D Micro enables accu­rate dis­place­ment and strain mea­sure­ments under high magnification.

Background

Three-dimen­sion­al dig­i­tal image cor­re­la­tion (DIC) has found wide­spread pop­u­lar­i­ty for strain mea­sure­ments due to its excel­lent accu­ra­cy, robust­ness and ease of use. How­ev­er, 3D mea­sure­ments have been dif­fi­cult to obtain on spec­i­mens where high mag­ni­fi­ca­tion is required. This is main­ly due to the lack of optics with suf­fi­cient depth-of-field to acquire two high mag­ni­fi­ca­tion images from dif­fer­ent view­ing angles.

Stereo micro­scopes over­come these depth-of-field lim­i­ta­tions. How­ev­er, the inter­nal con­struc­tion of stereo micro­scopes pre­vents prop­er cor­rec­tion of image dis­tor­tions using tra­di­tion­al mod­els, such as Sei­del lens dis­tor­tions. These uncor­rect­ed images will result in severe­ly biased shape and strain mea­sure­ments. In fact, it is not uncom­mon to observe bias lev­els of sev­er­al thou­sand microstrain.

To over­come this prob­lem, Cor­re­lat­ed Solu­tions, Inc., has devel­oped and patent­ed an easy-to-use cal­i­bra­tion method that does not suf­fer from the prob­lems asso­ci­at­ed with tra­di­tion­al para­met­ric dis­tor­tion mod­els. The cal­i­bra­tion method com­putes the non-para­met­ric dis­tor­tion fields of the stereo micro­scope and has been shown to com­plete­ly elim­i­nate shape and strain bias from the measurements.