UNIT 2.4 Optical Filters for Wavelength Selection in Fluorescence Instrumentation

  1. Turan Erdogan

Published Online: 1 APR 2011

DOI: 10.1002/0471142956.cy0204s56

Current Protocols in Cytometry

Current Protocols in Cytometry

How to Cite

Erdogan, T. 2011. Optical Filters for Wavelength Selection in Fluorescence Instrumentation. Current Protocols in Cytometry. 56:2.4:2.4.1–2.4.25.

Author Information

  1. Semrock, Inc., Rochester, New York

Publication History

  1. Published Online: 1 APR 2011
  2. Published Print: APR 2011


Fluorescence imaging and analysis techniques have become ubiquitous in life science research, and they are poised to play an equally vital role in in vitro diagnostics (IVD) in the future. Optical filters are crucial for nearly all fluorescence microscopes and instruments, not only to provide the obvious function of spectral control, but also to ensure the highest possible detection sensitivity and imaging resolution. Filters make it possible for the sample to “see” light within only the absorption band, and the detector to “see” light within only the emission band. Without filters, the detector would not be able to distinguish the desired fluorescence from scattered excitation light and autofluorescence from the sample, substrate, and other optics in the system. Today the vast majority of fluorescence instruments, including the widely popular fluorescence microscope, use thin-film interference filters to control the spectra of the excitation and emission light. Hence, this unit emphasizes thin-film filters. After briefly introducing different types of thin-film filters and how they are made, the unit describes in detail different optical filter configurations in fluorescence instruments, including both single-color and multicolor imaging systems. Several key properties of thin-film filters, which can significantly affect optical system performance, are then described. In the final section, tunable optical filters are also addressed in a relative comparison. Curr. Protoc. Cytom. 56:2.4.1-2.4.25. © 2011 by John Wiley & Sons, Inc.


  • fluorescence;
  • filter;
  • optical filter;
  • microscopy;
  • imaging;
  • wavelength;
  • interference;
  • tunable filter;
  • thin film;
  • dichroic beamsplitter