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Normal incidence Diffuse Optical Scatter Instrument (NDOSI)
Summary
The Normal incidence Diffuse Optical Scatter Instrument (NDOSI) is a new facility for measuring the hemispherical reflectance and transmittance of materials under direct and diffuse illumination in the visible range (400 nm to 800 nm). The measured quantities are used to investigate the diffuse optical properties of materials; these parameters are critical for understanding the interaction of light with optically diffusive materials.
NDOSI will provide calibration reference materials, solid and liquid tissue mimicking phantoms, measurements of scattering, absorption, reflectance, and transmittance of materials such as tissues, plant leaves, suspended solids and plankton for databases, model validation, and scales (e.g., turbidity).
Specifications/Capabilities
NDOSI is designed to be NIST’s national reference instrument dedicated to the measurement of the diffuse optical properties of samples at room temperature. Three laser lines and a laser-driven broadband light source can be alternatively used to illuminate a sample placed adjacent to an integrating sphere to measure the sample’s hemispherical reflectance and transmittance. A custom model-based analysis program has been developed to determine the optical coefficients and the associated uncertainties. The sample can either be solid or liquid (contained in a dedicated liquid cell).
Major Accomplishments
- Integration of a laser driven xenon light source
- Demonstration of hemispherical measurements of reflectance and transmittance under direct and diffuse illumination
- Comparison of the results with other NIST reference instruments
