Select ramp1 and set the interpolation to none.

Now gradation is gone, there is only slicing.

Now at frame 1 select white color in the ramp (circle on the left) and right click at the selected position box.

Press set key.

Now at frame 50, move white on top and set key.

Then create another ramp (as projection). This ramp will be used to follow slicing.

Connect projection2 to lambert2.incadescence