Simple Characterization of Cylindrical Diffuser Fibers With a Fluorescent Layer.

Area of Science:

• Optics and Photonics
• Biomedical Engineering
• Medical Imaging

Background:

• Cylindrical diffusers (CDFs) are crucial in laser-based medical therapies.
• Accurate measurement of light emission profiles is essential for CDF quality assurance.
• Existing methods may suffer from angle dependency and environmental factors.

Purpose of the Study:

• To develop a fast, simple, versatile, and reliable method for recording light emission intensity profiles of CDFs.
• To create an angle-independent measurement technique.
• To assess the impact of different media on emission profiles.

Main Methods:

• Utilized a fluorescent color glass filter (RG695) to convert red light (635 nm diode laser) into near-infrared fluorescence.
• Imaged the near-infrared fluorescence using a camera.
• Processed camera images to obtain emission intensity profiles.
• Compared CDF profiles from four manufacturers in air and transparent liquids.

Main Results:

• The developed method provides angle-independent intensity profiles with a single camera shot.
• Emission profiles significantly change in media with different refractive indices, depending on the diffuser tip's emission principle.
• Demonstrated the method's versatility in air and transparent liquids.

Conclusions:

• Converting emitted light to fluorescence eliminates angle dependence in recorded profiles.
• The method facilitates easy assessment of refractive index (mis)matching by immersing the setup in liquids.
• This measurement principle has potential for quality assurance of CDFs in interstitial laser thermotherapy and photodynamic therapy.