Portable thermal lens spectrometer with focusing system.

Area of Science:

• Analytical Chemistry
• Optical Spectroscopy
• Instrumentation Engineering

Background:

• Thermal lens spectrometry (TLS) is a sensitive technique for detecting low concentrations of analytes.
• Existing TLS systems can be complex and require precise alignment, limiting their portability and ease of use.
• Developing a portable and user-friendly TLS instrument with high performance is crucial for field applications.

Purpose of the Study:

• To develop a portable thermal lens spectrometer with a precise and integrated focusing system.
• To evaluate the focusing resolution and repeatability of the developed system.
• To demonstrate the performance of the instrument for sensitive chemical detection.

Main Methods:

• Development of a portable thermal lens spectrometer incorporating a novel focusing system.
• Utilizing astigmatism of a reflected excitation beam for depth-focused alignment.
• Employing the scattering effect of a transmitted probe beam for width-focused alignment.
• Evaluation using a microchannel with defined dimensions (250 µm width x 50 µm depth).

Main Results:

• Achieved focusing resolutions of 1 µm in the depth direction and 10 µm in the width direction.
• Demonstrated high repeatability for thermal lens signals (approx. 1% coefficient of variance) with a 40 µM xylenol solution.
• Established a limit of detection of 30 nM for xylenol solutions.
• Observed sensitivity 20-100 times higher than conventional spectrophotometry.

Conclusions:

• A practical and portable thermal lens spectrometer with a precise focusing system has been successfully realized.
• The developed focusing methods enable high-resolution alignment and repeatable measurements.
• The instrument's high sensitivity and low detection limit make it suitable for various analytical applications.