The 64e Velodyne LiDAR system's manual mentions the range of the sensor in meters (see page 2, second paragraph):
The HDL-64E is rated to provide usable returns up to 120 meters.
The manual's C appendix brings information about their software for reading and visualizing lidar data: Digital Sensor Recorder (DSR). It says on page 14, last paragraph:
Note: In live display mode, click on the double arrow button to begin display. The concentric gray circles and grid lines represent 10 meter increments from the sensor, which is depicted on the screen by a white circle.
You can use the sample data, which comes together with the DSR software CD, to extract descriptive information and statistics from this cloud and check the units by yourself.
Few months ago, I posted a tutorial about how one could do that using Fusion; the US Forest Service's software for lidar processing. See here:
Extracting descriptive information from a LiDAR cloud (.las files)