  Fabrication of large area (sub 1 cm cross-section) micro-optical components
in a short period of time (approximately 10 min) and with lesser number of
processing steps is highly desirable and cost-effective. In the recent years,
femtosecond laser fabrication technology has revolutionized the field of
manufacturing by offering the above capabilities. In this study, a fundamental
diffractive optical element, binary axicon i.e axicon with two phase or
amplitude levels, has been designed in three configurations namely conventional
axicon, photon sieve axicon (PSA) and sparse PSA and directly milled onto the
Sapphire substrate. The fabrication results revealed that a single pulse burst
fabrication can produce a flat and smooth profile than pulse overlapped
fabrication which gives rise to surface damage and increased roughness. The
fabricated elements were processed in IsoPropyl Alcohol and Potassium Hydroxide
to remove debris and redeposited amorphous Sapphire. An incoherent illumination
was used for optical testing of the components and a non-linear optical filter
was used for cleaning the noisy images generated by the diffractive optical
elements.
