Fabricating a Raman spectrometer using an optical pickup unit and pulsed power

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Optical Engineering

Background:

• Commercial Raman spectrometers are prohibitively expensive for many university laboratories.
• Optical pickup units (OPUs) are inexpensive, compact optical devices with structural similarities to spectrometers.
• There is a need for low-cost Raman spectroscopy solutions for educational and research settings.

Purpose of the Study:

• To investigate the feasibility of constructing a functional Raman spectrometer for under $1,000.
• To explore the use of an OPU as the core component of a low-cost Raman spectrometer.
• To characterize the performance of an OPU-based Raman spectrometer.

Main Methods:

• Fabrication of a Raman spectrometer using 3D-printed parts, a Raman edge filter, and a 520 nm laser diode.
• Utilizing a function generator as a pulsed power source to analyze spectrometer performance.
• Adjusting laser wavelength and background light intensity by varying frequency and duty ratio.
• Modulating Raman signal strength by adjusting the OPU's objective lens focal length.

Main Results:

• The OPU-based Raman spectrometer was successfully fabricated at a cost below $1,000.
• Laser wavelength shifted to longer wavelengths with increased duty ratios; higher frequencies reduced background light intensity.
• Raman signal strength was adjustable via the OPU's objective lens.
• Maximum error rate was ~11 cm⁻¹, and maximum intensity deviation was ~±6%.

Conclusions:

• An OPU-based Raman spectrometer can be constructed for less than $1,000, significantly reducing costs.
• Performance characteristics, including wavelength and signal intensity, can be controlled through power supply adjustments.
• Further cost reduction is possible by using a less dense optical density filter.