Metho­de zur Kom­pen­sie­rung des Streu­licht­an­teils bei der kon­ti­nu­ier­li­chen Modu­la­ti­ons­in­ter­fe­ro­me­trie

Beschreibung

At this time, the first mea­su­ring sys­tems which are based on the princip­le of the con­ti­nuous modu­la­ti­on inter­fe­ro­me­try, also known as pha­se-depen­ding or indi­rect time of- flight mea­su­re­ment, are lea­ving the labo­ra­to­ries and beco­me an inte­res­ting alter­na­ti­ve to estab­lis­hed clas­si­cal mea­su­re­ment princi­ples, like tri­an­gu­la­ti­on or ste­reo-visi­on. Based on this acqui­si­ti­on method of the third dimen­si­on many mea­su­ring tasks can be sol­ved easi­ly that have been put up with nume­rous dis­ad­van­ta­ges in the past resul­ting in gre­at efforts. In respect to this dis­ad­van­ta­ges, the refe­rence is made to the ste­reo-visi­on approach whe­re­as a huge amount of com­pu­ting power is necessa­ry deter­mi­ne the dis­pa­ri­ty map. Fur­ther­mo­re, this approach calls for the detec­tion of the requi­red fea­ture points in both images. Dis­ad­van­ta­ges, as alrea­dy descri­bed in the para­graph befo­re, don’t app­ly on the mea­su­re­ment sys­tems based on time-of-flight approach. Howe­ver, the­se sys­tems are sub­jec­ted to other limi­ta­ti­ons cau­sed by the under­ly­ing mea­su­re­ment princip­le its­elf and who­se imple­men­ta­ti­on results in mea­su­re­ment errors and ‑varia­ti­ons. The mathe­ma­ti­cal basics and the cor­re­spon­ding phy­si­cal model are given to deri­ve the errors and to deve­lop ade­qua­te cor­rec­tion and cali­bra­ti­ons methods. In addi­ti­on, the­re are other main­ly exter­nal effects that cor­rupt the mea­su­red distance: the geo­me­try of the regar­ded sce­ne its­elf. In this con­text, two pos­si­ble rea­sons or rather trig­gers have to be divi­ded: on one hand mul­ti-reflec­tions wit­hin the sce­ne and on the other hand, reflec­tions cau­sed by objects that are loca­ted in minor distance to the mea­su­re­ment sys­tem wit­hin its path of rays. The­se cau­ses will be named stray light in the fol­lowing. For the first case, merely an esti­ma­ti­on of the mea­su­re­ment error can be done using a simu­la­ti­on approach. Con­tra­ry to this, the error in the second case can safe­ly be cal­cu­la­ted by the infor­ma­ti­on (distance and ampli­tu­de) that can be extrac­ted from a taken shoot of the regar­ded sce­ne. The design of an appro­pria­te method for com­pen­sa­ti­on of the mea­su­re­ment error in the second case is taken cen­ter sta­ge of this the­sis. The desi­gned method based on sim­pli­fied sce­nes, gene­ra­ted in the labo­ra­to­ry, is vali­da­ted on real sce­nes. The vali­da­ti­on and veri­fi­ca­ti­on of this method is con­fir­med by the use of estab­lis­hed sta­tis­ti­cal tools.