HAM A
£1,361.00 excl. VAT
This unique high quality absorber material, available only from Precision Acoustics, has special acoustic properties which make it ideal for a range of applications
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Additional information
| Lead time | Off the shelf (if available) |
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NPL high quality acoustic absorber for ultrasonic applications
This unique high quality absorber
material, available only from Precision Acoustics, has special acoustic properties which make it ideal for a range of applications, including:
- Absorbing targets for radiation force balances, to minimise the errors associated with the reflecting targets of most commercially available radiation force balances.
- Low ultrasonic echo (anechoic) material as a specialist coating for hydrophone mounts used for characterisation of medical ultrasonic equipment employing continuous-wave or long toneburst excitation.
Physical Specification
- Based on polyurethane rubber material two layers: top layer – acoustic impedance matched to water backing layer – partially air-loaded to increase transmission loss
- Interface between the two types of material pyramidal in structure to scatter incident ultrasound
- Dimensions: 200 mm x 250 mm x 14 mm
- Coefficient of linear thermal expansion is 200 ppm/oC
- Density of 1010 + 20 kg / m3
- Specific gravity is 1.01
- The longitudinal wave speed (1 MHz to 10 MHz) ≈1500 m/s.
- Acoustic impedance is 1.5 MRayls
- There is residence to Isopropyl Alcohol (IPA) and Tricholethylene
- It can be affected by ketones (MEK, Acetone) – swell
- Dichloromethane – swell and breakdown
- Avoid prolonged exposure to Ozone and UV
- The stability is very stable due to cross-linked nature of polymer
- Material can be precision cut in various geometries to meet exact end-user requirements, e.g., simple discs of 50 mm diameter
Acoustical Specification
- High transmission loss, > 30 dB/cm/MHz
- High echo-reduction, > 42 dB at 1 MHz degrading to 35 dB at 10 MHz
- The NPL absorber fully meets the requirements for radiation force balance targets, covering the frequency range 1 MHz to 15 MHz3
- HAM A absorber has been used to perform power measurements up to 20 watts*
References
- Robert T. Hekkenberg, Klaus Beissner and Bajram Zeqiri, Therapy-level ultrasonic power measurement, Final Technical Report for Project SMT4-CT96-2139, 2000
- Bajram Zeqiri and Catherine J. Bickley, A new anechoic material for medical ultrasonic applications, Ultrasound in Med. & Biol., Vol. 26, No. 3, pp. 481-485, 2000
- IEC 61161 (1992). Ultrasonic power measurements in liquids in the frequency range 0.5 to 25MHz. IEC, Geneva, Switzerland
