STUDY ON THE HIGH-SPEED SCANNING AND HIGH RESOLUTION OF CT-SCAN TYPE LASER-SHEET 2D-INSTANTANEOUS CONCENTRATION METER

(1)目的：从硬件和软件两个方面对已报道的试验仪(“CT-扫描式无旋转部件瞬时浓度仪”)进行了改进。(2)激光分选扫描机构的改进：(1)激光分选机构的改进：(1)激光分选机构由原来的由发射器输出的激光步进电机进行机械扫描，改为采用柱面透镜展开激光片材，完全避免了旋转部件。来自发射器阵列的激光被连续地打开和关闭。(B)来自发射器的穿过浓度场的激光信号已被接收单元阵列接收并连续记录。通过连续记录信号强度，大大缩短了采样周期。(3)分析系统的改进：(A)虚拟载荷法：如前文所述，在反问题中用双傅立叶表示法来表示未知场的常规方法，由于没有旋转部件的仪器从单向搜索场获得的信息太少，所以不能得到令人满意的结果。而Hino(1974)提出的类似于样条法的“虚载荷法”被成功地应用。(4)结果与结论：通过对小波变换硬件和软件的改进，实现了仪器的高性能和高分辨率。

(1) Aims : Several improvements to the trial instrument ("CT-scan Type Instantaneous Concentration Meter with no rotating parts") previously reported have been made from the standpoint of both hardware and software.(2) Improvement in Laser Shedding and Scanning Mechanism : (a) Laser shedding mechanism has been changed from a mechanical scan by stepping motor of laser beams from emiters, to shedding laser sheet expanded by cylindrical lens, avoiding rotating parts completely. Laser lights from an array of emitters are switched on and off, successively. (b) Signals of laser light from emitters which are passed through the concentration field have been received by an array of receiving units and recorded continuously. By the continuous recording of signal intensities, the sampling period was considerably shortened.(3) Improvement in Analysis System : (a) 'Virtual Load Method' : As described in the previous paper, the conventional means to express an unknown field in the inverse problem through the double Fourier expression, does not give a favorable result, because the information obtained from the one directional search of the field by the instrument without rotational parts is too scarce. While the "Virtual Load Method" proposed by Hino (1974), an idea similar to the spline approximation, is successfully applied. (b) Application of Wavelet Transform to Remove Noise : Wavelet transform is applied to suppress noise and recover the pure signals.(4) Result and Conclusion : Effect of Wavelet Transform Technique : High performance and high resolution of the instrument have been accomplished by these improvements of hardware and software wavelet transform.