Depth enlargement and homogenization from plant-OCT observations by using optical clearing

In this research, a compact and lightweight Time Domain (TD)-OCT for plant measurements is developed. The leaves (Orchis graminifolia and Trifolium repens) were immersed in two kinds of liquids to make them transparent, expand the depth, and homogenize the signals of OCT images. Optical clearing using a chlorine-based cleaner reduces the internal signal and increases the measurement depth by removing the internal structures. Since chlorine-based cleaners enhance the vein signal, this liquid is useful for diagnosing the disease that occurs in veins. Optical clearing of plant-clearing agents can detect layer changes with internal refractive index changes by reducing light scattering. Since the plant-clearing agent makes the OCT image uniform, this liquid is useful for diagnosing the small changes inside the tissue due to the disease. Applying transparency liquids to the plant field measurement can quantitatively evaluate changes in internal structure and refractive index due to disease or environment. The proposed method of the combination of compact OCT and optical clearing can obtain small changes in the veins, palisade tissue, and spongy tissue.