Micron" Green sorce Monochromativ Light Unit is an "Echo Friendly" constant frequency light sorce to check Flatness.Normally yellow orange light from a sodium vapour lamp light sorce is used to check the flatness. The work experience shows this light takes much time to get constant light and working in this light sorse id tiresome to eyes. We have developed a green monochrometic light which have a power saving light sorce and ir ready instantantly when swithc on. The fringes in green monochromatic gives no fatiuge to eyes. Flatness calculations and checking is same.