Optical feedback characteristics in a helium neon laser with a birefringent internal cavity

The output characteristics of optical feedback in a helium neon laser with a birefringent internal cavity are studied systematically in five different regions of the gain curve for the two orthogonally polarized modes. When the laser operates in the two end regions of the laser gain curve, one of the two orthogonally polarized modes will be a leading one in optical feedback. Strong mode competition can be observed. However, when the laser operates in the middle region of the laser gain curve, the two modes can oscillate equally with optical feedback. Besides the intensity of the two polarized lights, the total light intensity is also studied at the same time. M-shaped optical feedback curves are found. Particularly, when the average intensities of the two lights are comparable, the intensity modulation curve of the total light is doubled, which can be used to improve the resolution of an optical feedback system.

Online Monitoring the Products Quality by Measuring Cavity Pressure during Injection Molding

Injection molding is a complicated production technique for the manufacturing of polymer products. During injection molding, it＇s hard to predict molding quality; the injection molding parameters, such as mold temperature, melt temperature, packing pressure and packing time, affect the final properties of product. The cavity pressure is a significant key factor. Residual stress and injection molding weight are significantly affected by the cavity pressure. This study created an approach to predict weight of injection-molded by real-time online cavity pressure monitoring. This study uses a 6-inch with thickness lmm light guide panel and the largest area beneath the pressure curve of time as well as the maximum pressure as its characteristic. The upper and lower limits of the control are set to ＋2 standard deviations, and GUI （Graphical User Interface）-based LabVIEW software is used to perform calculation and analysis of the pressure curve. The results of the experiment show that the online internal cavity pressure monitoring system can effectively monitor the quality of the molded products. In 500 injection molding cycle tests, its error rate was less than 8%, whereas the deviation in mass of the molded products selected through the system＇s filtering process was successfully controlled to be within ±4%.

Aerodynamic characteristics of store during lateral jet assisted separation from cavity using free drop technique

Aimed at the problem of store separation from internal cavity,this paper innovatively puts forward a separation scheme of using lateral jet to assist store safe separation.The jet ensures that the store is continuously subjected to down head moment during separation,so as to ensure safe separation.The wind tunnel free drop test technique with lateral jet is established,which can ensure that there is no support interference in the motion process of the store and more truly simulate the motion of the store.The feasibility of the new separation scheme is proved by wind tunnel test.The test shows that the new scheme can also change the more dangerous state into a safe state.Through the analysis of the test data,the pitching moment coefficients of the store under different pressures in the high-pressure cylinder are obtained,and the effects of aircraft and cavity on the pitching moment of the store are obtained.The 3 stages of store passing through cavity shock wave are found.The results show that the lateral jet provides the store with continuous head down moment,and makes the store overcome the head up moment caused by the shock wave in front of the cavity,so as to ensure the safety of separation.