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Beam Attenuation Meter (BAM)

The beam attenuation meter is specifically designed for Autonomous Underwater Vehicles to accommodate size and drag considerations.

Sea-Bird Scientific’s Beam Attenuation Meter is the next generation transmissometer specifically designed for Autonomous Underwater Vehicles (AUVs), where size and drag are primary considerations.

  • Compact size
  • Rugged construction
  • High precision and stability
  • Digital electronics
  • Protected optics
  • Flush mountable


Length 19.56 cm
Height 12.45 cm
Width 6.35 cm
Weight in air  3.28 kg
Weight in water 2.06 kg
Internal air volume  454 cc



Output resolution 14 bit
RS-232 output 19200 baud
Connector  MCBH-6-MP
Power input 7.5-15 VDC
Operating current 35 mA (532 and 650 nm)
Sample rate to 8 Hz



Rated depth 1000 m
Temperature range -2 to 38 deg C
Temperature storage -40 to 70 deg C
Temperature stability 0.02% FS/deg C
Long term stability (6hrs) 0.02% FS/Hr
Short term noise 0.027% FS Std dev over 1 minute



Wavelengths 470, 532,  or 650 nm
Optical pathlength 10 cm
Acceptance angle ~ 1 deg
Precision 0.003 m-1 @ 1 Hz (532 and 650 nm)
Linearity 99% R2
Specifications are subject to change without notice.


The list below includes (as applicable) the current product brochure, manual, and quick guide; software manual(s); and application notes.

What should I use to lubricate bulkhead connectors?

We recommend keeping the connectors on your meter lubricated using a good quality silicone spray lubricant, such as 3M Silicone Spray or Loctite 8021 spray. These can be purchased at your local hardware store. Avoid silicone grease. It is messy and attracts contaminants.

Do not use WD-40. It will destroy connectors.

How do I clean the optical surfaces on my transmissometer?

What is the input voltage range for my instrument?