Concepts in Confocal Microscopy

Laser scanning confocal microscopy represents one of the most significant advances in optical microscopy ever developed, primarily because the technique enables visualization deep within both living and fixed cells and tissues and affords the ability to collect sharply defined optical sections from which three-dimensional renderings can be created. Development of modern confocal microscopes has been accelerated by new advances in computer and storage technology, laser systems, detectors, interference filters, spectral technology, and fluorophores for highly specific targets.
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Review Articles

Introduction to Confocal Microscopy

Confocal microscopy has advantages over widefield optical microscopy, including the ability to eliminate or reduce background information away from the focal plane and collect serial optical sections from thick specimens.

Fluorophores for Confocal Microscopy

Biological laser scanning confocal microscopy relies on fluorescence as an imaging mode due to the high degree of sensitivity afforded by the technique coupled with the ability to specifically target structural components.

Laser Scanning Confocal Microscope Simulator

Explore multi-laser fluorescence and differential interference contrast (DIC) confocal imaging in this tutorial.

Fluorescence Excitation & Emission Fundamentals

Fluorescence is a member of the luminescence family of processes in which molecules emit light from electronically excited states created by either a physical, mechanical (friction), or chemical mechanism.

Spectral Bleed-Through Artifacts in Confocal Microscopy

Spectral bleed-through of fluorescence emission occurs due to the broad bandwidths and asymmetrical spectral profiles exhibited by fluorophores, can be a problem in laser scanning confocal fluorescence microscopy.

Choosing Fluorophore Combinations for Confocal Microscopy

Explore the matching of dual fluorophores with efficient laser excitation lines and determination of the bleed-through level that can be expected as a function of the detection window wavelength profiles in this tutorial.

Interference Filters for Fluorescence Microscopy

The utilization of specialized and advanced thin film,interference filtershave enhanced the versatility of fluorescence techniques, far beyond the capabilities of the earlier use of gelatin and glass filters.

Non-Coherent Light Sources for Confocal Microscopy

Reviewed in this article are the merits and limitations of non-coherent light sources in confocal microscopy, both as light sources for confocal illumination and as secondary sources for widefield microscopy in confocal microscopes.

Resolution & Contrast in Confocal Microscopy

In a fluorescence microscope, contrast is determined by the number of photons collected, the dynamic range of the signal, optical aberrations of the imaging system, and the number of picture elements (pixels) per unit area.

Introduction to Lasers

Lasers are designed to produce and amplify this stimulated form of light into intense and focused beams. The word laser was coined as an acronym for Light Amplification by the Stimulated Emission of Radiation.

Laser Systems for Confocal Microscopy

The lasers used in laser scanning confocal microscopy are high-intensity monochromatic light sources, which are useful for techniques including optical trapping, lifetime imaging studies, and total internal reflection fluorescence.

Acousto-Optic Tunable Filters (AOTFs)

Several benefits of the AOTF combine to enhance the versatility of the latest generation of confocal instruments, and these devices are becoming popular for control of excitation wavelength ranges and intensity.

Confocal Microscope Objectives

The contrast and resolution of fine specimen detail, the depth within the specimen from which information can be obtained, and the lateral extent of the image field are all determined by the objective.

Confocal Microscope Scanning Systems

Three principal scanning variations are employed to produce confocal microscope images. Each technique has features that make it advantageous for specific confocal applications, but limit the usefulness in others.

Signal-to-Noise Considerations

In any quantitative assessment of imaging capabilities utilizing digital microscopy techniques, including confocal methods, the effect of signal sampling on contrast and resolution must be considered.

Electronic Light Detectors: Photomultipliers

In laser scanning confocal microscopy, the collection of secondary emission gathered by the objective can be accomplished by classes of photosensitive detectors, including photomultipliers, photodiodes, andCCDs.

Electronic Imaging Detectors

Over the past several years, the rapidly growing field of fluorescence microscopy has evolved from a dependence on traditional photomicrography using emulsion-based film to one in which electronic images are the output of choice.

Applications in Confocal Microscopy

Applications available to laser scanning confocal microscopy includes a variety of studies in neuroanatomy and neurophysiology, as well as morphological studies of a wide spectrum of cells and tissues.

Fluorochrome Data Table

As a guide to fluorophores for confocal and widefield fluorescence microscopy, the table presented lists many commonly-used fluorochromes, with their respective peak absorption, and emission wavelengths.

Glossary of Terms in Confocal Microscopy

Featured here are resources provided as a guide and reference tool for visitors who are exploring the large spectrum of specialized topics in fluorescence and laser scanning confocal microscopy.

Confocal Microscopy Interactive Tutorials

Discover and explore the gallery of various interactive Java tutorials designed to explain and aid students visually in understanding complex and difficult concepts in confocal microscopy.

References and Web Resources

Concepts in Confocal Microscopy Web Resources

Laser scanning confocal microscopy (LSCM) is a tool that has been extensively utilized for inspection of semiconductors, is now becoming a mainstream application in cell biology. The links provided in this section from The Evident Scientific Microscopy Resource Center web site offer tutorials, instrumentation, application notes, technical support, glossaries, and reference materials on confocal microscopy and related techniques.

Confocal Microscopes for Life Science Solutions

FV5000

Confocal Laser Scanning Microscope

  • Extraordinary clarity, speed, and reliability driven by groundbreaking innovations
  • SilVIR™ detectors deliver photon-level quantitation, exceptional sensitivity, and ultra-high signal-to-noise
  • Unmatched dynamic range captures the full signal spectrum and prevents saturation
  • High-speed 2K resonant scanning and high-density 8K galvo scanning in one platform
  • FLUOVIEW Smart™ software simplifies operation with intuitive controls and AI-powered automation
  • TruResolution™ auto correction collar optimizes focus for over 20 objectives
  • Modular design supports up to 10 laser lines and future multiphoton upgrades
  • Laser Power Monitor (LPM) ensures stable illumination and reproducible results over time

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FV5000MPE

Multiphoton Laser Scanning Microscope

  • Compact fiber-pigtailed lasers enable deep, quantitative imaging in scattering tissue
  • One-, two-, or three-line simultaneous MPE laser excitation for millimeters deep imaging
  • SilVIR™, TruAI, and TruSight™ technologies deliver outstanding signal-to-noise and clarity
  • MPE-optimized objectives, TruResolution™ auto correction collar, and automated IR laser alignment maintain sharp focus
  • Available as an FV5000 system upgrade or a complete MPE system
  • Fully tunable laser configurations available for more advanced multiphoton applications

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Multiphoton Laser Scanning Microscope – FV4000 MPE

  • Acquire accurate, quantitative image data from the macro scale to subcellular structures
  • Obtain more information from a single multicolor image
  • Monitor neuron and other essential dynamics with high-speed imaging

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FLUOVIEW Laser Scanning Microscope Solutions – SilVIR Detetor

  • Combines a silicon photomultiplier and patented * fast signal processing for lower noise, higher sensitivity, and improved photon resolving capabilities
  • High detection efficiency provides superior signal-to-noise to bring weak fluorescence to life
  • Capture vivid fluorescence images with no offset adjustments
  • Precisely quantify image intensity for more reliable data

*Patent number US11237047

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Industrial Solutions

LEXT OLS5500

Hybrid 3D Optical Profilometer

  • Traceable surface measurements from the nanometer to micrometer scale
  • Laser scanning microscopy (LSM), white light interferometry (WLI), and focus variation microscopy (FVM) in one award-winning platform
  • First 3D optical profilometer to offer guaranteed accuracy and repeatability* for both LSM and WLI measurements
  • WLI mode delivers up to 40x faster measurement throughput than conventional LSM
  • Exceptional precision across surfaces with in-house engineered optics
  • Intuitive interface and smart automation streamline operation for users of all levels
  • AI-enhanced and high-throughput workflows with PRECiV™ software integration

*Based on Evident’s internal research as of October 2025. The guaranteed accuracy and repeatability apply only if the device has been calibrated according to the manufacturer’s specifications and is in defect free condition. Calibration must be performed by an Evident technician or an Evident-authorized specialist.

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LEXT OLS5100

Confocal Laser Scanning Microscope for Material Analysis – LEXT OLS5100

  • Guaranteed measurement accuracy of 3D surface shape at the submicron level*
  • High-performance optics reduce aberration throughout the entire field of view
  • High-resolution image stitching and fast scanning speeds to quickly acquire images
  • User-friendly interface and intuitive software enabling operation by all user types

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Contributing Authors

David W. Piston - Department of Molecular Physiology and Biophysics, Vanderbilt University, 702 Light Hall, Nashville, Tennessee, 37212.
Kenneth R. Spring - Scientific Consultant, Lusby, Maryland, 20657.
Matthew Parry-Hill, Thomas J. Fellers and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.