Terahertz time domain spectroscopy technique used for evaluation of thickness and optical cum dielectric properties of table and fertile eggshells

The paper reports the use of THz time domain spectroscopy for the measurements of thickness, refractive index and dielectric constants of chicken egg shells. Twelve numbers of table and fertile egg samples were selected. The experiment was performed in the reflection geometry using a fiber-coupled terahertz source between 0 and 4.0 THz range. The reflected time domain signal from the inner eggshell-membrane boundary and the outer eggshell interface was used, to determine shell thickness. The results were verified with Field Emission Scanning Electron-Microscopy (FESEM). In the next step, the obtained Time/frequency domain spectra data were used to ascertain the R.I., absorption coefficients, and real and imaginary parts of the dielectric constants for the first time. It was noticed that the values of R.I. of normal eggs at 0.8 THz were higher than 2.5 as compared to fertile eggs. Similarly, the absorption coefficient values for nonfertile eggs lie between 2 and 14 cm ^-1 compared to fertile eggs, which lie between 2 and 10 cm ^-1 range.The most important aspect of our study is related to measurements of real and imaginary parts of dielectric constants between 1.2 and 3.0 THz range the nonfertile eggs show a steep drop in values between 4 - 2.0 range while fertile eggs show an almost linear response of 4 0.0 in the given frequency range. The imaginary parts show nonfertile egg values between 7.0 and 3.75 while fertile eggs show a consistent result of the order of 5.0. It further opens a new channel to enhance the poultry industry. The results were verified using field emission scanning electron microscopy results. This non-destructive technique can play a very important role in the poultry industry in minimizing waste and maximizing efficiency.