In recent years, biotechnology has been widely used in production and living. The research on processing biomaterials and developing them into new functional types has also been gradually carried out. In this paper, the influence of water content of microbial material on the extinction properties of infrared band was studied from the aspects of composition and structure. The sample of moisture content of microbial was established. The qualitative law between the water content of microbial particle and its absorption property was given. The quantitative relationship between the water content of microbial particle and its scattering property was calculated. Under the conditions of strong attenuation, the optimal solution of microbial materials based on water content is designed. The results show that when the transmittance is less than 10%, the complex refractive index <i>n</i> of microbial particles can be changed within the range of 0 < Δ<i>n</i> ≤ 0.072 by controlling the amount of intracellular bound water. The controllability and variability of complex refractive index n can improve the extinction performance of microbial materials in the infrared band by up to 50%.
Coherent Doppler lidars (CDL) and coherent differential absorption lidars are widely applied in the measurements of atmospheric wind and constituents respectively. To improve the detection range of heterodyne lidars, the demands for laser linewidth are studied based on the statistical theory and Monte Carlo simulations. The signal to noise ratio (SNR) and the spectrum of intermediate frequency (IF) signal are analyzed under different laser power and linewidth. When the detection range is beyond the coherent length, the IF signal can still be measured, and the power spectrum of IF signal will be broadened, which results in the peak value decrease in the power spectrum. In heterodyne Doppler lidars, the frequency extraction errors of IF signal fluctuate with SNR. To realize the velocity measurement performance for wind and other moving targets, detection performances with various laser linewidth are analyzed according to the 3σ criterion. The calculations indicate that better results can be obtained with larger powers when the laser linewidth is relatively wider and that the effective detection range of lidar can be longer than the coherent length for lasers with certain linewidth. To verify the analysis, heterodyne experiments are carried out based on the fiber delay lines and fiber lasers with different linewidths, and the SNR is controlled by a variable optical attenuator. The results show that measurements with large laser power can reduce the errors caused by the power spectrum broadening of IF signal. The analysis may aid the determination of laser power and linewidth in heterodyne lidars.
With the increasing demands for new biological extinction materials in military and civilian fields, the artificially prepared flocculent biological particles are equivalent to bullet rosette particles. Then the unit particles with different numbers and lengths of branches are built, and the aggregated particles with different structures are built further. Next the structures of biological particles are characterized by parameterization. And the discrete dipole approximation method is used to calculate the extinction efficiency factor for biological particles. The results indicate that the structures and spatial arrangement of unit particles have great impact on the extinction performance of biological particles. The extinction performance of unit particles is positively correlated to the number and length of branches in the far infrared waveband. Furthermore, the extinction performance of aggregated particles is positively correlated to the porosity in the far infrared waveband. The model provides a theoretical basis for the further development and morphology control of biological extinction materials.
With the emergence of strong light source, laser weapons in the modern war, the threat of damage to the photoelectric sensor and the human eye, the laser protection technology has begun to be paid attention to and widespread concern. In the laser protective materials, we can divide it into the protective material based on the principle of linear optics and the protective material based on the principle of nonlinear optics. In this paper, two different mechanisms of laser protective materials are introduced, and their development and application are reviewed.
A multilayer structure of microbial cells can result in the multiple attenuation of electromagnetic waves, making the
biological particles have a strong ability of extinction. And the activity of microorganism is also an important factor that
affects the change of laser transmittance. In this paper, the dynamic change of the transmittance of 632.8nm laser in
biological materials is measured. The results show that: when the biological material is stimulated by the laser, the stress
response occurs, and the movement of escaping light is the main factor of causing the change of the transmittance. This
provides a reference for the further development of the biological extinction materials.
Spore is an important part of bioaerosols. The optical characteristics of spore is a crucial parameter for study on bioaerosols. The reflection within the waveband of 2.5 to15μm were measured by squash method. Based on the measured data, Complex refractive index of Aspergillus oryzae spores within the waveband of 3 to 5μm and 8 to 14 μm were calculated by using Krames-Kronig (K-K) relationship. Then,the mass extinction coefficient of Aspergillus oryzae spores within the waveband of 3 to 5μm and 8 to 14μm were obtained by utilizing Mie scattering theory, and the results were analyzed and discussed. The average mass extinction coefficient of Aspergillus oryzae spores is 0.51 m<sup>2</sup>/g in the range of 3 to 5μm，and 0.48m<sup>2</sup>/g in the range of 8 to 14μm. Compared with common inorganic compounds, Aspergillus oryzae spores possesses a good extinction performance in infrared band.
Quantum Sensors like Quantum Radar and Lidar based on the interference of non-classical states can achieve super-sensitivity beyond the Standard Quantum Limit (SQL). But as the photons transporting in atmosphere, the environmental interaction causes quantum de-coherence and results in the reduction of super-sensitivity range of the quantum sensors. The most significant effect of atmospheric transmission is photon loss along with phase fluctuation. In this letter, we introduce both the photon loss and phase fluctuation by adding a fictitious beam splitter in the signal arm of Mach- Zehnder interferometer (MZI). The density matrix with N00N and M&M' entangled states being the input states under the condition of photon loss and phase fluctuation is given respectively. Then as the optimal detection schemes parity operator is used as the detector and the formula of the sensitivity is derived. The super-sensitivity range of M&M’ and N00N states with de-coherence are simulated. As a consequence, with high photon loss M&M’ states shows the better phase sensitivity than N00N states but the N00N state is better when the loss is smaller than 20%. And with pure phase fluctuations N00N states get the longer range. M&M’ states is sensitive to the transmittance difference between two arms of the interferometer.
Microorganism aggregated particle swarm, which is quite an important composition of complex media environment, can be developed as a new kind of infrared functional materials. Current researches mainly focus on the optical properties of single microorganism particle. As for the swarm, especially the microorganism aggregated particle swarm, a more accurate simulation model should be proposed to calculate its extinction effect. At the same time, certain parameters deserve to be discussed, which helps to better develop the microorganism aggregated particle swarm as a new kind of infrared functional materials. In this paper, take Aspergillus Niger spore as an example. On the one hand, a new calculation model is established. Firstly, the cluster-cluster aggregation (CCA) model is used to simulate the structure of Aspergillus Niger spore aggregated particle. Secondly, the single scattering extinction parameters for Aspergillus Niger spore aggregated particle are calculated by using the discrete dipole approximation (DDA) method. Thirdly, the transmittance of Aspergillus Niger spore aggregated particle swarm is simulated by using Monte Carlo method. On the other hand, based on the model proposed above, what influences can wavelength causes has been studied, including the spectral distribution of scattering intensity of Aspergillus Niger spore aggregated particle and the infrared spectral transmittance of the aggregated particle swarm within the range of 8～14μm incident infrared wavelengths. Numerical results indicate that the scattering intensity of Aspergillus Niger spore aggregated particle reduces with the increase of incident wavelengths at each scattering angle. Scattering energy mainly concentrates on the scattering angle between 0～40°, forward scattering has an obvious effect. In addition, the infrared transmittance of Aspergillus Niger spore aggregated particle swarm goes up with the increase of incident wavelengths. However, some turning points of the trend are associated with the absorption capacity of the swarm. When parameters of the swarm are set as follows: each Aspergillus Niger spore aggregated particle contains 40 original particles, the radius of original particle is 1.5μm, the density of aggregated particles is around 200/cm<sup>3</sup>, the measurement area is 4 meters thick, under conditions mentioned above, the infrared transmittance can be less than 10% between the incident wavelengths of 9.5～13μm. In the end, all the results provide the basis for better developing the microorganism aggregated particle swarm as a new kind of infrared functional materials and precisely choosing the effective defiladed infrared band.