Qhov tshaj tawm uas lub dav hlau monochromatic yoj pem hauv ntej propagates raws nws cov kev taw qhia ib txwm hu ua theem tshaj tawm ntawm nthwv dej. Qhov ceev ntawm lub teeb yoj lub zog mus los yog hu ua ray velocity. Cov kev taw qhia uas lub teeb mus raws li pom los ntawm tib neeg lub qhov muag yog cov kev taw qhia uas lub teeb mus.

Rau cov uas tsis yog-sib nqus ib leeg siv lead ua, cov theem tshaj tawm ntawm lub teeb yoj lub teeb yog perpendicular rau cov kev taw qhia ntawm hluav taws xob hloov chaw D thiab magnetic field siv H, thaum lub zog propagation kev taw qhia ntawm lub teeb yoj yog perpendicular rau H thiab hluav taws xob siv zog E. Lub dielectric tas li ntawm anisotropic optical media yog qhov thib ob-txiav tensor.D thiab E feem ntau tsis sib luag, yog li cov kev taw qhia ntawm theem tshaj tawm v thiab linear tshaj tawm v_r feem ntau tsis sib xws. Lub Angle suav nrog α nruab nrab ntawm lawv yog hu ua discrete angle, uas yog lub luag haujlwm ntawm cov kev taw qhia ntawm theem tshaj tawm (los yog kab hluav taws xob tshaj tawm) thiab cov kev taw qhia ntawm D (los yog E) (raws li qhia hauv daim duab hauv qab no). Cov theem tshaj tawm thiab cov linear tshaj tawm feem ntau tsis sib npaug, thiab kev sib raug zoo ntawm lawv yogv=v_rcosα.

Qhov piv ntawm qhov ceev ntawm lub teeb mus rau hauv lub tshuab nqus tsev (c) mus rau nws theem tshaj tawm v nyob rau hauv ib tug muab kev taw qhia nyob rau hauv ib tug anisotropic optical nruab nrab yog hu ua lub refractive index rau qhov kev taw qhia. Ib yam li ntawd, qhov ratio ntawmc mus rau qhov ceev ntawm lub teeb nyob rau hauv ib qho kev taw qhia n_r=c/v_r yog hu ua lub refractive index ntawm lub teeb nyob rau hauv qhov kev taw qhia.

WISOPTIC yoj daim hlau