isi-sys Homepage

Shearography / ESPI Systems


Foto SE2 Sensor Shearografie Scherografie by isis-sys

She­aro­gra­phy and elec­tro­nic speck­le pat­ter inter­fe­ro­me­try (ESPI) are laser based, opti­cal mea­su­re­ment methods, working full field and non contact.

The She­aro­gra­phy sys­tems are appli­ed for non des­truc­ti­ve test­ing, but also for vibra­ti­on, defor­ma­ti­on and strain mea­su­re­ment. The reso­lu­ti­on of the dif­fe­ren­ti­al defor­ma­ti­on is a frac­tion of the wave length only und thus in the nano­me­ter ran­ge and below. The laser wave length is the refe­rence sca­le, so the reso­lu­ti­on is inde­pen­dent of the field of view. The field of view is in the ran­ge of mm² to m². The pre­pa­ra­ti­on of the object in only requi­red for sur­faces, which are opti­cal­ly non cooperative

Read more…


The image shows a typi­cal she­aro­gra­phic mea­sur­ment result for non des­truc­ti­ve test­ing. The object is a honey­comb panel with dif­fe­rent pre­pared defects, which beco­me visi­ble even app­ly­ing small ther­mal load via light radiation.

 Application: Non Destructive Testing

The main field of appli­ca­ti­on of the She­aro­gra­phy sys­tems of isi-sys is non des­truc­ti­ve test­ing (NDT).

The full field dif­fe­ren­ti­al defor­ma­ti­on mea­su­re­ment of she­aro­gra­phy enables to loca­te espe­ci­al­ly struc­tu­ral­ly and mecha­ni­cal­ly rele­vant defects such as delamination’s, cracks or void due to local inho­mo­ge­neous defor­ma­ti­on and strain dis­tri­bu­ti­on, when an exter­nal load is applied.

In the prac­ti­cal appli­ca­ti­on, this can be a ther­mal load via light sources or hot air guns, dyna­mi­cal load via Pie­zo­s­ha­kers or mecha­ni­cal loa­ding steps such as chan­ge of the inter­nal pres­su­re of tubes and tanks or vacu­um loa­ding by vacu­um cham­bers or vacu­um hoods.

Read more…




DIC (Digital Image Correlation)


Digi­tal image cor­re­la­ti­on is appli­ed in solid mecha­nics, mate­ri­al rese­arch and deve­lo­p­ment of mecha­ni­cal­ly loa­ded mate­ri­als, com­pon­ents and struc­tures. DIC con­tri­bu­tes here espe­ci­al­ly due to the non cont­act and full field mea­su­re­ment of defor­ma­ti­on and dis­pla­ce­ments and the deri­ved quan­ti­ties such as strain, vibra­ti­on, moti­on and velo­ci­ties for ana­ly­sis of the mecha­ni­cal pro­per­ties. The results are use for vali­da­ti­on of simulations.


The mea­su­re­ment results ori­gi­na­te from the sur­face of the object its­elf usual­ly by ste­reo came­ra sys­tems and eva­lua­ted with VIC 2D/VIC 3D soft­ware, but also within the solid by com­pu­ter tomo­gra­phy sys­tems (CT´s) and VIC Volu­me. isi-sys is sys­tem inte­gra­tor for VIC soft­ware in Euro­pe and clo­se deve­lo­p­ment part­ner of Cor­re­la­ted Solu­ti­ons, USA.

The reso­lu­ti­on of the defor­ma­ti­on and strain as well as its spa­ti­al and time reso­lu­ti­on is depen­ding on the sys­tem con­fi­gu­ra­ti­on. DIC sys­tem of isi-sys reach nano­me­ter sen­si­ti­vi­ty as well as time reso­lu­ti­on in nano­se­cond ran­ge. They have been appli­ed on field of view below one mm² und abo­ve 100m², such as on rota­ting wind tur­bi­ne bla­de with a dia­me­ter of 114m.

Read more…


Application Range of DIC for Strain and Deformation Measurement

DIC is appli­ed for sta­tic and dyna­mic three dimen­sio­nal strain and defor­ma­ti­on mea­su­re­ment in the ran­ge of from 0,001% up to 1000% and abo­ve as well as for fati­gue test­ing and moni­to­ring. Using high reso­lu­ti­on came­ras with line­ar and low noi­se sen­sor pro­per­ties a high spa­ti­al reso­lu­ti­on can be achie­ved, too. Time reso­lu­ti­on is actual­ly pos­si­ble up to 5 mil­li­on frames per second.

DIC enab­led a mea­su­re­ment, which have not been pos­si­ble with con­ven­tio­nal methods such as at high tem­pe­ra­tures, at high strains or on small field of view with high spa­ti­al reso­lu­ti­on. In a num­ber of cases DIC has repla­ced con­ven­tio­nal methods such as strain gau­ges or exten­so­me­ters – espe­ci­al­ly in the area lf deve­lo­p­ment and rese­arch due to the full field and non cont­act working principle.

Due to its advan­ta­ges and due to the impro­ved came­ras and incre­asing com­pu­ta­ti­on power the digi­tal image cor­re­la­ti­on sys­tems have dri­ven con­ven­tio­nal opti­cal methods for strain and defor­ma­ti­on such as Pho­to­ela­s­ti­ci­ty and Elec­tro­nic Speck­le Pat­tern Inter­fe­ro­me­try out of the mar­ket to a wide extend.

Read more…



Video Stroboscope


Foto High Speed Videostroboskop by isi-sys

Used for simp­le visua­liza­ti­on, moni­to­ring and recor­ding of vibra­ti­ons and rota­ti­ons in slow-moti­on. For quan­ti­ta­ti­ve eva­lua­ti­on in sub­pi­xel ran­ge, it can be exten­ded with image cor­re­la­ti­on (see above).

Read more…




Application: Vibration Analysis

The com­bi­na­ti­on of Video Stro­bo­sco­pes or High Speed Came­ras with digi­tal image cor­re­la­ti­on (see abo­ve) is used for vibra­ti­on mea­su­re­ments app­ly­ing the pha­se reso­nan­ce or pha­se sepa­ra­ti­on method. The VIC-FFT modu­les enables to ana­ly­se ope­ra­ti­on deflec­tion modes full field and 3D based.

Read more…





Piezoshaker Systems


Photo Piezoshaker PS X 03 by isi-sys


Desi­gned for vibra­ti­on exci­ta­ti­on in the ran­ge from 1–100kHz espe­ci­al­ly for non des­truc­ti­ve test­ing and vibra­ti­on ana­ly­sis. The pie­zo­s­ha­ker exci­ta­ti­on sys­tems include spe­cial light weight high power pie­zo ampli­fiers for mobi­le appli­ca­ti­on in NDT with she­aro­gra­phy and thermography.

Read more…






Application: Non Destructive Testing

The video on the right shows the lamb waves, gene­ra­ted by the pie­zo­s­ha­ker, that is atta­ched at the bot­tom of the spe­ci­men. The waves tra­vel across the object sur­face and exci­te the five local sub­sur­face defects on the top. The local defects vibra­te dif­fer­ent­ly, depen­ding on their local mecha­ni­cal pro­per­ties (stiff­ness).

Read more…