Nipkow disk systems may be designed in either tandem scanning or monoscanning variations. However, modern microlens arrays and sophisticated disk design enhancements, coupled to laser illumination, have expanded the potential applications for spinning disk confocal microscopes. Systems employing the Nipkow disk-scanning concept have typically utilized noncoherent broad-spectrum light sources (such as arc-discharge lamps) for illumination rather than lasers, and the overall lack of brightness has severely limited their use in fluorescence applications. The stage-scanning and beam-scanning configurations are single-beam methods, while the spinning disk approach is a multibeam scanning technique. Each technique has performance features that make it advantageous for specific confocal applications, but that limit the usefulness in others. Fundamentally equivalent confocal operation can be achieved by employing a laterally translating specimen stage coupled to a stationary illuminating light beam ( stage scanning), a scanned light beam with a stationary stage ( beam scanning), or by maintaining both the stage and light source stationary while scanning the specimen with an array of light points transmitted through apertures in a spinning Nipkow disk also know as a scanning disk (see Figures 1 and 2). Three principal scanning variations are commonly employed to produce confocal microscope images.
The point-by-point signal collection process requires a mechanism for scanning the focused illuminating beam through the specimen volume under observation. Confocal imaging relies upon the sequential collection of light from spatially filtered individual specimen points, followed by electronic signal processing and ultimately, the visual display as corresponding image points.
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