## 1 Introduction  
Structural ceramics find many applications in microfeature products due to their exceptional properties such as wear resistant, chemical inertness, high temperature strength, and dimensional stability. One of the most important and readily available structural ceramic is Alumina. Alumina micro-featured products have applications in many areas like microelectronics due to their excellent dielectric strength and in microreactors as heat and corrosive-resistant material with low thermal expansion. Similarly, they are being utilized for many wear resistance applications like parts in micro-pumps, valves, and thread/wire guides. Conventional processing methods to fabricate micro features in structural ceramics are not able to meet the designed requirements in various areas like micro-electronics, bio-medical applications and microreactors etc. The microfeatures in these applications require high dimensional accuracy with very fine surface finish. In addition, absence of microcracks, residual stresses, and heat affected zones is crucial to ensure smart product architecture resulting in high performance integration [1; 2]. Traditionally structural ceramics are processed using techniques similar to powder metallurgy. However, manufacturing of high precision and defect free ceramic micro parts using these methods poses significant challenges in terms of tool development and raw material preparation. Good quality ceramic parts require high precision molds and very fine powder preparation. These constraints restrict the technology to high volume production and thus are not suitable for applications requiring customized parts and shorter product development times. Other processing methods like electrochemical deposition and photolithography are also being investigated for ceramic micro features. However, these methods are not easy to implement, involve chemical handling, and are associated with long processing times [3; 4]. Additive manufacturing methods which have been primarily developed for polymeric materials are also being adapted to manufacture metallic and ceramic micro parts. These methods do not require any mold preparation and processing is computer controlled. However, the quality of the micro parts is not comparable to other methods in terms of porosity, residual stresses, and surface finish [5]. Micro-machining through mechanical cutting is the most prevalent method to fabricate micro parts. With precision machine tools, it is possible to produce good surface finish and form accuracy. However, at the same time, these tool contact-based methods are subjected to excessive tool wear and micro-cracks especially for ceramic micro parts. In contrast non-conventional machining methods like micro-electric-discharge machining (Micro-EDM), micro-ultrasonic machining (Micro-USM), and micro-laser-beam machining (Micro-LBM) are able to produce extremely fine accuracy and better surface integrity with little or no tool wear. Specifically, Micro-LBM is an excellent choice for machining ceramic parts as it provides better process control, improved dimensional accuracy, and easier set-up in comparison to other methods [6]. Microprocessing of ceramics using an Nd:YAG or excimer laser has been investigated by many researchers using pulse widths in milli-, micro-, nano-, and pico-second range while generating different microstructures. Effects of laser intensity/fluence, wavelength, scan speed, pulse repetition rate, pulse width, and air pressure were investigated on different performance measures like dimensional accuracy, ablation efficiency, heat affected zone, recast layers, surface roughness, and microcracks etc. Microstructure development in titanium nitrate using femtosecond lasers was carried out by [PERSON] et al. [7]. They compared circularly polarized radiation with linearly polarized radiation and concluded that the former produces good surface finish and increased ablation rates using the same laser fluence.