Detection of discontinuity densities in composite materials
View Patent ↗A method for detecting suspended discontinuity densities in a material is provided. The method includes transmitting terahertz electromagnetic radiation toward a surface of the material. This radiation is received at an expected location after interacting with the material. The power level of the received radiation is measured and deviation from the expected value is used to determine a suspended discontinuity density gradient in the material. The method can be used with either reflected radiation or transmitted radiation. Embodiments of the method can calculate the index of refraction in the material and correlate this with the suspended discontinuity density of the material.
1. A method for detecting dispersion of agglomerates in a material comprising:
transmitting terahertz frequency electromagnetic radiation toward positions on a surface of the material;
determining an expected reception location for the transmitted radiation after interaction with the material based on the laws of reflection and refraction;
determining an expected reception intensity for the transmitted radiation after interaction with the material;
receiving the terahertz electromagnetic radiation after the terahertz electromagnetic radiation has interacted with the material at the expected reception location;
detecting an intensity of the received radiation at positions on the surface of the material;
determining a refractive index gradient from the detected intensities; and
providing an indication of agglomerate dispersion in the material if a refractive index gradient exists.
2. The method of claim 1 wherein:
transmitting is performed on a first side of the material; and
receiving is performed on a second, opposite side of the material such that terahertz electromagnetic radiation is transmitted through the material.
3. The method of claim 1 wherein:
transmitting is performed on a first side of the material; and
reception is performed on the first side of the material, such that received radiation is reflected from the material.
4. The method of claim 3 wherein incident radiation is incident perpendicularly toward a surface of the material and reception occurs along substantially the same path as transmission.
5. The method of claim 1 wherein:
said material is a substrate and said agglomerates are a plurality of micro-inclusions suspended therein; and
said step of providing an indication of agglomerate dispersion comprises determining a density gradient of micro-inclusions in the substrate.
6. The method of claim 1 wherein said step of determining an expected reception intensity comprises establishing the expected reception intensity based on other regions of the material.
7. A method for detecting dispersion of agglomerates in a material comprising:
transmitting terahertz electromagnetic radiation toward positions on a first surface of the material;
determining a first expected reception location for each position on the first surface for transmitted terahertz electromagnetic radiation based on the laws of refraction;
determining a second expected reception location for each position on the first surface for reflected terahertz electromagnetic radiation based on the laws of reflection;
determining a first expected reception intensity for transmission of terahertz electromagnetic radiation through the material;
determining a second expected reception intensity for reflection of terahertz electromagnetic radiation from the material;
receiving the terahertz electromagnetic radiation at the first expected reception locations on a second opposite side of the material such that terahertz electromagnetic radiation is transmitted through the material;
receiving the terahertz electromagnetic radiation at the second expected reception locations on the first side of the material such that terahertz electromagnetic radiation is reflected from the material;
detecting an intensity of the received terahertz electromagnetic radiation at the first expected terahertz reception locations;
detecting an intensity of the received terahertz electromagnetic radiation at the second expected terahertz reception locations; and
determining a refractive index gradient across positions on the material from the detected intensities at the first expected terahertz reception locations and the second expected terahertz reception locations;
providing an indication of agglomerate dispersion in the material based on the determined refractive index gradient.
8. The method of claim 7 wherein:
said material is a substrate and said agglomerates are a plurality of micro-inclusions suspended therein; and
said step of providing an indication of agglomerate dispersion comprises determining a density gradient of micro-inclusions in the substrate.
9. The method of claim 7 wherein said step of determining a first expected reception intensity comprises establishing the first expected reception intensity based on other regions of the material.