.PS
cct_init

# Usual defs...
qrt=dimen_/4;
hlf=dimen_/2;
dim=dimen_;

linethick_(2); L1:line right_ dim; linethick_
source(with .center at Here+(2mm__,0),AC,4mm__)
linethick_(2); L2:line from L1.end+(4mm__,0) right_ dim; linethick_
move right_ 3* dim
linethick_(2); L3:line right_ dim; linethick_
source(with .center at Here+(2mm__,0),AC,4mm__)
linethick_(2); line from L3.end+(4mm__,0) right_ dim; linethick_

move to 1/2 of the way between L2.end \
  and L3.start  
Orig:Here  

# Spacing ito wavelength
s=10;

# scaling factor
factor = 0.65;

for theta = 0 to twopi_ by 0.01 do {
  e = abs(factor*(2*sin(theta)*cos(pi_*s*cos(theta))));
  line to Orig+(e*cos(theta),e*sin(theta))
}

"\tiny Interferometer" at (5.5*dim,-dim)
.PE