## 5 Conclusions  
The surface-temperature-controlled medical laser system developed in our laboratory is capable of ensuring the success and reproducibility of PTT modalities and patient safety even when using a sample population representative of wide optical and thermal property ranges encountered in clinical conditions. Our system successfully maintains tissue surface temperatures at required target values to induce desired thermo-physiological effects and prevents excessive thermal damage even when using different laser powers. It comprises relatively inexpensive components that perform efficiently even when using the simplest control method. It has an easy to operate, simple design that can be set up and used in the clinical environment in an appropriate enclosure without requiring complicated training. Thus, it may accelerate and enable the translation of novel photothermal laser applications currently confined to the controlled and uniform conditions of the laboratory (e.g., laser-tissue welding, PTT of granulation tissue, cartilage reshaping) into the clinic by rendering them more successful, reproducible, and safe even for a wide range of subjects which cannot be provided by manual dosimetry (surgeon's decision) or fixed-dosimetry. Additionally, researchers may use our system for investigating and developing new, and improving pre-existing, photothermal laser applications on various biological tissues by monitoring tissue surface temperature, controlling laser exposure, and facilitating gathering of information of related parameters (i.e., thermal characterization of tissues). Using the temperature monitorization capability of our system, we noticed that low laser power values accentuate the effect idiosyncratic differences of optical and thermal properties of tissues have on their temperature-time responses. This interaction between low laser power and idiosyncratic properties of tissues led to a wider range of exposure durations (required to reach target temperatures) in temperature-controlled laser irradiation. Regulating photothermal medical laser applications by tissue temperature feedback is currently the gold standard of the trade. Our future work will focus on implementing laser power modulation and improving the control algorithm to monitor and manipulate the rate of tissue surface temperature increase. We will also conduct experiments to demonstrate the in vivo effectiveness of our system. Investigation of methods for determining tissue emissivity to ensure measurement accuracy and reliability is another course of further research. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app13010237/s1](https://www.mdpi.com/article/10.3390/app13010237/s1)]([https://www.mdpi.com/article/10.3390/app13010237/s1](https://www.mdpi.com/article/10.3390/app13010237/s1)), Figure S1: Box and whiskers plot of thermal denaturation diameters and depths; Figure S2: Exemplary bovine liver photothermal denaturation photographs; Table S1: Results of post hoc tests using [PERSON]'s procedure after one-way ANOVA of thermal denaturation diameter and depth values. References [33; 34; 35; 36] are cited in the supplementary materials. Conceptualization, O.K. and M.G. ; methodology, O.K. and M.G. ; software, O.K. ; formal analysis, O.K. and I.D. ; investigation, O.K. and I.D. ; resources, O.K. and M.G. ; data curation, O.K. ; writing--original draft preparation, O.K. ; writing--review and editing, I.C. and M.G. ; visualization, O.K. ; supervision, I.C. and M.G. ; project administration, O.K. and M.G. ; funding acquisition, O.K. and M.G. All authors have read and agreed to the published version of the manuscript. This research was funded internally by the Bogazici University Research Fund Grant No. BAP-8500 14 XM2. **Institutional Review Board Statement:** Ethical review and approval were waived for this study because ex vivo tissues were acquired from an abattoir. **Informed Consent Statement:** Not applicable.