Case Study: 650 nm Long Wave Pass Filter

Case Study: Using Long Wave Pass Filters on Schott RG645 Glass to eliminate self-Fluorescence

Customer Challenge: A customer involved in the security imaging sector faced issues with unwanted fluorescence degrading the quality of their imaging system. The fluorescence from samples and the surrounding environment interfered with the system’s ability to capture high-contrast, accurate images, leading to unreliable results The customer required a solution to effectively block this unwanted fluorescence while ensuring efficient transmission of the desired imaging wavelengths.

Vortex’s Solution: Vortex applied a long wave pass filter with an edge position at 650 nm, i.e. very close to that of the Schott RG645 glass, this eliminates the fluorescence. Referring to the graphs below, the optical coating blocks wavelengths below 630 nm but allows the transmission of wavelengths above 680 nm. Fluorescence is caused when the body of the glass absorbs photons and then re-emits photons of a longer wavelength. The long pass filter eliminates this effect by preventing absorption of the incoming light by the RG645 glass, the incoming light is reflected by the coating.

Result/Conclusion: The addition of the long pass filter significantly improved the image quality in the customer’s system. It eliminated the unwanted fluorescence, resulting in clearer, high-contrast images with improved detail and accuracy.