Question: do while loop in plot

dear sir i want to plot a graph for different values of h(z) by applying do loop, hear is my codes

In K1 it should take first h(z)

In K2 it should take second h(z)

IN K3 it should take third h(z) 

restart:
h:=z->1-(delta2/2)*(1 + cos(2*(Pi/L1)*(z - d1 - L1))):
h:=z->1-(delta2/2)*(1 + cos(2*(Pi/L2)*(z - d2 - L2))):
h:=z->1+(delta2/2):
K1:=((4/h(z)^4)-(sin(alpha)/F)-h(z)^2+Nb*h(z)^4):
K2:=((4/h(z)^4)-(sin(alpha)/F)-h(z)^2+Nb*h(z)^4):
K3:=((4/h(z)^4)+(cos(alpha)/F)+h(z)^2+Nb*h(z)^4):
lambda1:=Int(K1,z=0..0.2):
lambda2:=Int(K2,z=0.2..0.4):
lambda3:=Int(K3,z=0.4..0.6):
lambda:=(lmbda1+lambda2+lambda3):
> 
F:=0.3:
L1:=0.2:
d1:=0.2:
d2:=0.2:
L2:=0.3:
alpha:=Pi/6:
plot( [seq(eval(lambda, Nb=j), j in [0.1,0.2,0.3])], delta2=0.02..0.1);