**2. Laser‐enhanced topography properties**

Micro/submicro‐treated surfaces are popularly used in scaffold systems for bone and tissue implant applications. The surface topography properties of a material, particularly rough‐ ness, are influential on the cell adhesion rate of bone‐like apatite to surfaces. Increasing the cell adhesion rate to the surface of a material increases the biocompatibility of the material. Thus, surface texturing of materials to enhance their biocompatibility is an effective method in the fabrication of implant devices [26–28]. The effects of laser irradiation on the surface topogra‐ phy properties of materials are the main advantage of laser surface texturing. Laser parame‐ ters, including frequency, power, and laser scanning parameters, can influence these material properties greatly [27].

The irradiated surface area of a material has increased surface irregularities. In return, the exposed area is more readily available for cell attachment, which enhances the apatite‐inducing ability and cell adhesion rate of the material [27–31]. Furthermore, laser treatment of the materials increases the surface temperature up to oxidation temperature, and results in the creation of thin layers of oxide upon the surface. An increase in the oxidation of the surfaces increases the wettability of surface of the material. Consequently, this leads to an increase in the apatite‐inducing ability of the material and greatly improves the biocompatibility of the implant surfaces [30–35].

#### **2.1. Laser system**

The nanosecond laser used for obtaining all the results discussed in this chapter was a Nd:YAG pulsed laser system (SOL‐20 by Bright Solutions Inc). The maximum output power is 20 W with a wavelength of 1064 nm and a repetition rate ranging between 10 and 100 kHz. This laser emits pulses of 6–35 ns pulse duration. The diameter of circular output beam from the laser is around 9 mm. The diameter of beam is reduced to 8mm by using an iris diaphragm before entering to galvo‐scanner. A two‐axis galvo‐scanner (JD2204 by Sino Galvo) with the input aperture of 10 mm and beam displacement of 13.4 mm was used for beam scanning since it has a high scanning speed (to 3000 mm/s). In order to focus the normal beam to the surface of Ti, scan lens of a focal length of 63.5 mm was used. The theoretical focused laser spot diame‐ ter (*d*0) is calculated to be 20 μm. During the experiment, the spot size may be bigger due to scatter and misalignment. The average laser fluence was 900 μJ at the frequency of 10 kHz.

The scanning parameters including scanning speed, and scanning configurations can be adjusted through the software operating the laser. When the combination of parameters is adjusted with this software, along with power and frequency set for laser irradiation, the desired pattern is irradiated across the surface of the selected material.
