To export particles to a file (or a series of files), select File → Export File from the menu. After choosing an output filename and a file format, the export settings dialog lets you specify the animation frames and the particle properties to be exported.

If you pick an output filename that ends with the .gz suffix, the file will be automatically compressed by OVITO.

Note that OVITO exports the final results of the modification pipeline. That means, for instance, if you have deleted some particles, OVITO will export only the remaining particles to the output file. The modification pipeline is re-evaluated for every animation frame being exported.