Case Study: Improved Fluorescence Detection Performance with an Avant™ Filter Set Aug 1, 2025 by IDEX Health & Science Orientation Localization and quantitation of biochemical components in biological tissue are enabled through microscope-based detection of fluorescent probes that selectively bind to those components. Detection of the probe fluorescence is accomplished using an optical filter set, made up of one each exciter, dichroic, and emitter filter. For single-probe detection, the exciter and emitter filters each have a single passband around the center wavelength and blocking outside the bandwidth. The dichroic has a long-pass edge near the wavelength at which the exciter and emitter filters’ optical transmission profiles cross over. Problem Statement Fig. 1. Comparison of standard BrightLine® (blue) and Avant™ (red) passband positions for the Cy5.5 fluorophore. The yellow band highlights the fluorescence emission missed by the standard filter set. Solution In 2021, IDEX Health & Science devised the new Semrock Avant™ optical filter family to overcome this limitation. These sets were to improve upon the industry standard BrightLine® filter sets in three ways: (1) Improved control over manufacture to limit spectral edge variation in manufacture, (2) Steeper transition between transmission and blocking on the critical edges, and (3) Deeper complementary blocking adjacent to the critical edges. Method Outcome Fig. 2. AF555-stained myosin from sheep skeletal muscle imaged with Avant (left) and BrightLine (right) filter sets. See text for details. Conclusion This comparison validates the Avant filter set concept of using steeper edges with reduced edge jitter and increased blocking to increase signal and signal-to-noise in short Stokes Shift fluorescent probes.