Compact, portable LBS-300 beam samplers provide measurements of beams with up to 15 mm dia and power levels from 10 mW to 400 W. Devices transmit nearly all of beam, with less than 0.1% passed on to camera. They include 3 neutral density filter sets, fixed or continuous, and attach to C-mount, CS-mount, or Ophir-mount cameras. Available in 4 configurations, units enable 2 filters to be combined for adjustable attenuation down to 100,000,000:1.