It is very difficult to create very broadband dielectric coatings, however metal coatings are naturally effective over a wide range of wavelengths.  Sadly, they also absorb a significant amount of energy and as the reflectivity is pushed higher, the absorption also increases.  Our metal coated etalons, or Metalons, are a compromise that achieves a reasonable finesse of about 2.5 using coatings that are about between 30% and 40% reflective from 350nm to 900nm.  The result is a peak transmission of about 40%, so if you need really high transmission and no loss then this is not your etalon.  But the modulation is about 75% so if your application calls for wavelength monitoring then the metalon might just work great and will almost certainly work for your wavelength range!

• Material:  Fused Silica, 7980 OA Grade
• Wavelength range: 350nm to 900nm
• Finesse: approximately 2.5, varies by wavelength
• FSR: see thickness table
• Thickness uniformity (wedge) <2nm rms over the clear aperture
• Clear aperture: 20.0mm
• Surface quality: 80/50 or better
• Surface figure: λ/10
• Diameter: 25.4
• * If your etalons require coatings then we can use our fluid jet polishing system to reduce the wedge and increase the finesse

Contact us anytime for custom items - that's what we do