What is Holography and Maser

Holography

When an object is photographed by a camera, a two dimensional
image  of  three  dimensional  object  is  obtained.  A  three  dimensional
image   of   an   object   can   be   formed   by   holography.   In   ordinary
photography,  the  amplitude  of  the  light  wave  is  recorded  on  the
photographic film. In holography, both the phase and amplitude of the
light waves are recorded on the film. The resulting photograph is called Hologram

MASER
The   term   Maser   stands   for   Microwave   Amplification   by
Stimulated  Emission  of  Radiation.  The  working  of  maser  is  similar  to
that of laser. The maser action is based on the principle of population
inversion  followed  by  stimulated  emission.  In  maser,  the  emitted
photon, during the transition from the metastable state belongs to the
microwave  frequencies.  The  paramagnetic  ions  are  used  as  maser
materials. Practical maser materials are often chromium or gadolinium
ions doped as impurities in ionic crystals. Ammonia gas is also a maser
material.  Maser  provides  a  very  strong  tool  for  analysis  in  molecular spectography