Optoelectronic device for measuring the humidity of silkworth cocoons

Abstract

Purpose given work was creation of an optoelectronic device for measuring the humidity of silkworm cocoons on basis mid-IR LEDs. An optoelectronic device has been developed for measuring the humidity of silkworm cocoons based on mid-IR LEDs, allowing measurements in real mode with an accuracy of 1.5%. Analysis of the spectral characteristics of silkworm cocoons shows that in the optical range of 0.4…1.2 μ m, the cocoon shell transmits radiation well , and radiation with a wavelength of 1…2 μ m is well reflected. In the spectral region of 1.8-2.2 μ m, the reflectivity of silkworm cocoons is 85%, then drops to 14" at wavelengths of 3 μm. Transmission of radiation by the pupa in the spectral region of 0.4-10 μ m was not detected. The obtained data on the optical properties of silkworm cocoons made it possible to use the principle of reflection to control humidity, because at wavelengths of 1.95 and 2.22 μ m , where there are maxima and minima of water absorption, the shell of silkworm cocoons transmits little IR radiation, but at these wavelengths it has good reflectivity, so it is necessary to use the principle of reflection of IR radiation. In the optoelectronic device for measuring the humidity of silkworm cocoons, LEDs with emission spectra of 2.2 μ m are used as a reference channel , and LEDs with emission spectra of 1.94 μ m are used as a measuring channel . To record signals, a photodiode with a wide sensitivity range of 1.5 - 2.4 μ m was used. A schematic diagram has been proposed that ensures the main condition for two-wave optoelectronic devices, in terms of timing and temperature stability of LED parameters and the equality of their initial reference, measuring radiation fluxes, which determine the measurement accuracy.