308 Excimer Lens:
The cutting-edge technology that "concentrates" medical-grade 308 nm light into a single lens

I. What Exactly Is It
The 308 excimer lens is not an ordinary lens but a specialized "optical window" or "light-guiding lens" designed for 308 nm xenon chloride (XeCl) excimer light sources. It is typically made from high-purity fused silica or CaF? as the substrate, with both sides coated with a 308 nm narrow-band anti-reflection coating (R < 0.5%). This allows the therapeutic beam to be directed to the lesion with minimal loss while blocking other wavelengths to avoid burning healthy skin.

II. Why Only 308 nm
? Precision: 308 nm lies at the narrow-spectrum peak of UVB, which can be selectively absorbed by T-cells and melanocytes in the affected area, inducing T-cell apoptosis and activating tyrosinase.
? Safety: The penetration depth is only 1-1.5 mm, reaching only the superficial dermis without damaging deeper tissues.
? Efficacy: Clinically proven, 10-20 sessions of irradiation can lead to visible pigment islands in vitiligo and psoriatic lesions.

III. Three Key Metrics of the Lens

1. Transmittance: ≥ 95%@308 nm;

2. Blocking Depth: OD ≥ 3 for wavelengths below 297 nm and above 320 nm, preventing stray light;

3. Energy Threshold: Can withstand continuous irradiation at 50 mW/cm2 for 30 minutes without thermal distortion.

IV. Typical Applications
? Handheld/desktop 308 excimer phototherapy devices—the lens serves as both a "window" and a "filter." Doctors can replace the lens with different shapes (dot, oval, rectangle) based on the lesion’s shape for precise targeting.
? Home-use compact 308 LED phototherapy pens—integrate miniature 308 nm LEDs with focusing lenses, allowing patients to perform supplemental light therapy at home under medical guidance.