An alternative method to multiple point scanning for high-speed confocal imaging is to use a single broad "bar" of excitation light to sweep across the sample. By repeatedly sweeping the bar at a high rate, and descanning the fluorescence through a slit aperture, the sample can be imaged at a very high rate.

In the 1990s the Meridian InSight slit scanning confocal microscope used this technology to achieve rapid scanning. The technology was limited by very low resolution (note the VCR and file camera) and is now obsolete.

Meridian slit scanning confocal microscope beam path. The important feature is the "Variable Slit".

The contemporary implementation of the slit scanner is the Carl Zeiss LSM 5 Live confocal microscope. Important technological advantages are:

• Beam-shaping optics to create a 1-pixel wide scan beam
• Variable slit width aperture ("pinhole")
• High-speed detectors and electronics.

The system can acquire confocal images at 120 images/sec, 512x512