I have some serious doubts regarding He-Ne laser: 1. In He, the ground state energy value is taken is 0 eV and the meta stable state is taken as 20.61 eV. similarly in Ne the meta stable levels are taken as 20.66 and 18.7 eV respectively. How these values are arrived at? In Bohr's expression the ground energy value of hydrogen atom is taken as -13.6 eV. Next one is -3.4 eV and so on. How these negative values help in calculating the energy values of He and Ne? Because all the values expressed in the said laser are positive and none of them bear negative sign. 2.Why He is preferred along with Ne? Is it not possible to directly excite the Ne atoms to the meta stable state to produce laser, because it is only the neon atoms that are responsible for laser action? Is there any special reason? 3.After emitting the photons of wavelength 6328 Angstrom units, it is said that the electrons jump from the meta stable state of value 20.66 eV to another lower level 18.7 eV where it emits incoherent beam by spontaneous emission. Then, does it mean that the resultant beam from He-Ne laser consist of a mixture of both coherent and incoherent beams? Does it not violate one of the basic characteristics of laser which should be necessarily coherent? 4. Finally, has any one found the reason for why only certain substances contain the so called meta stable levels but others do not, in nature?