SetDirectory["~/Factorisation/"];
<<kappaLib.m
<<helper.m

vars={x0,x1,x2,x3};

AA[D1_]:= (({{1, 0, 0, 0}, {0, (1/2) (-D1+(Sqrt[4+(D1^2)])), 0, 0}, {0, 0, (1/2) (-D1+(Sqrt[4+(D1^2)])), 0}, {0, 0, 0, -1}}));
BB[D1_]:= (({{1, 0, 0, 0}, {0, (1/2) (-D1-(Sqrt[4+(D1^2)])), 0, 0}, {0, 0, (1/2) (-D1-(Sqrt[4+(D1^2)])), 0}, {0, 0, 0, -1}}));

FullSimplify[vars.AA[D1].vars]
FullSimplify[vars.BB[D1].vars]

Fresnel surface function of x0, x1^2+x2^2, x3

vars={x0,0,x2,x3};

f1[D1_]:=FullSimplify[vars.AA[D1].vars]
f2[D1_]:=FullSimplify[vars.BB[D1].vars]

F[D1_]:=toEqs[{f1[D1],f2[D1]}]

Viewpoint and ViewVertical

vp={1.9182892524446804`,2.4632276376155486`,1.3048662572241434`};
vv={0.13721054563794138`,0.19011461479660596`,0.9721263803675306`};

F[-25]

{f1[d]==0,f2[d]==0}

d=-25;
p1=ContourPlot3D[{f1[d]==0,f2[d]==0},{x0,-1,1},{x2,-1.1,1.1},{x3,-1,1},Axes->False,Boxed->False,ViewPoint->vp,ViewVertical->vv]

d=0;
p2=ContourPlot3D[{f1[d]==0,f2[d]==0},{x0,-1,1},{x2,-1,1},{x3,-1,1},Axes->False,Boxed->False,ViewPoint->vp,ViewVertical->vv]

d=25;
p3=ContourPlot3D[{f1[d]==0,f2[d]==0},{x0,-1,1},{x2,-1,1},{x3,-1,1},Axes->False,Boxed->False,ViewPoint->vp,ViewVertical->vv]

all=Show[GraphicsGrid[{{p1,p2,p3}}]]

printNotebook["Plot_IV.pdf"]