The Cosine Similarity Technique: A new method for smart EXCIMER laser control

Area of Science:

• Laser-material interactions
• Spectroscopy
• Biomedical engineering

Background:

• Smart laser control is crucial for precision in surgical procedures.
• Non-contact photoacoustic spectroscopy (NCPAS) offers a non-invasive method for material analysis.
• Developing advanced techniques for real-time material identification is essential for enhancing laser control.

Purpose of the Study:

• To advance smart laser control by analyzing organic polymer spectra using cosine similarity.
• To evaluate the efficacy of non-contact photoacoustic spectroscopy (NCPAS) combined with cosine similarity for material discrimination.
• To explore the potential of this technique for applications in eye surgery.

Main Methods:

• Experiments utilized polyethylene and polyamide samples subjected to photoablation with a 193 nm excimer laser at 200 Hz.
• Acoustic signals from laser ablation were captured using a capacitor microphone, amplified, and digitized.
• Cosine similarity technique was applied to compare polymer spectra, with performance assessed via receiver operating characteristic analysis.

Main Results:

• The cosine similarity technique achieved approximately 98% accuracy in material recognition at a 200 Hz laser repetition rate.
• The method demonstrated high precision in distinguishing between different organic polymers based on their acoustic spectra.
• Real-time analysis of acoustic signals enabled rapid material identification.

Conclusions:

• The cosine similarity method (CSM) provides a rapid, precise, and promising pathway for smart laser control.
• Future steps include creating spectral databases, utilizing higher laser repetition rates, and integrating NCPAS data with laser positioning.
• This technique holds significant potential for improving accuracy and safety in laser-based surgical applications.