IMAP

Advanced particulate characterization: the Inverse multi-angle Polarimeter

The IMAP (Inverse Multi-Angular Polarimeter) Nephelometer measures polarized scattered light at multiple angles and at multiple wavelengths. As with our other instruments, we use our feedback flow control system to collect data at multiple size bins ranging from PM1 to PM10. Owing to the small size of the sampling chamber and the overall efficiency of the system, this allows us to determine a full particle size distribution within a span of just 5 minutes. This advanced instrument collects a huge amount of data thanks to its cutting-edge technology: 3 wavelengths x 7 angles x 2 polarization orientations x 4 size bins.

We highly suggest using IMAP for an in-depth understanding of particulate properties. Given its unique combination of aerodynamic and optical sizing, it can be used to effectively connect satellite and ground-based measurements for comprehensive air quality research. To manage all of this detailed information, we use a sophisticated GRASP data retrieval algorithm which allows us to accurately determine: particle mass, size distribution, scattering phase function, polarization phase function, real refractive index of the particles, sphericity factor of the particles.

  • Instrument size: 86 cm x 38 cm x 32cm
  • Inlet height: 110 cm
  • Flow rate: 2 to 16 LPM (Alaric AE102-2)
  • Data: Saved to internal hard drive. Real-time access via Ethernet, RS2323 and RS485.
  • Calibration: Built-in clean reference cycle.
  • Gas calibration: CO2 and clean air every 3–6 months depending on operating conditions.
  • Power: Mains AC power. 120 or 240-Volt systems (50 and 60Hz). 600 W maximum load. A 5-Amp circuit breaker is included that also acts as the on-off switch.
  • Time resolution: 1 min averaging (recommended); 15 sec averaging (minimum).
  • Angular ranges measured: 8 View angles centered at 5° (unpol.), 10.6°, 31.8°, 52.9°, 95.3°, 116.5°, 137.6°, 158.8°.
  • Instantaneous field of view < 7.5°.
  • Wavelengths: (3) 450 nm, 520 nm and 638 nm.
  • Polarization orientations: 2 Parallel and perpendicular to the scattering plane.
  • Size measurements: Independent optical and aerodynamic size measurements.
    • Aerodynamic: 4 Size bins selected up to PM10 (possible every 5min)
    • Optical: Continuous function from 0.05 to 15um (possible every 1 min)

The IMAP can provide complete size distribution measurements every 5 minutes, particle mass, full scattering as well as polarization phase function, real refractive index of the particles and sphericity factor.

We suggest IMAP or in-depth understanding of particulate properties. Given its unique combination of aerodynamic and optical sizing can be used to connect satellite and ground based measurements for air quality research.

Can the instrument be connected to sampling manifolds rather than direct air intake (as long as pressure upfront the cyclone does not significantly deviate from ambient pressure)?

Yes the instrument can be connected to manifolds. The instrument can also operate without the cyclone if that is a concern for the user.

Can the flow rate be chosen freely, or is it fixed for a given upper diameter cut-off in the cyclone mounted in the inlet?

The active flow rate of the instrument is limited by its internal blower (fan). If the user wants a flow rate outside the range of our blower, the user can always use an external pump or blower.

Can the instrument also run at low ambient pressure (with potentially shifted flow rate or cut-off range)?

Yes, the instrument can run at lower pressure. Pressure correction may be needed for the aerodynamic behavior of the cyclone or for Rayleigh scattering considerations.