Instrument Development: 4-D Near-Infrared Chemical Imaging Using Snapshot Tomography

在化学系化学测量和成像项目的支持下，威斯康星大学密尔沃基分校（UWM）的Sung教授开发了近红外（NIR）范围内的四维（4D）化学成像新仪器。近红外高光谱成像已被广泛用于无损质量检测，然而，现有的方法不能检查一个复杂的内部结构的样品或检测深埋在三维体积内的化学杂质，因为深度信息丢失在记录的二维投影图像。传统的3-D断层成像方法需要扫描机构，这显著增加了数据采集时间和仪器的复杂性。Sung教授和他的团队正在开发一种使用快照断层扫描技术的仪器，这种技术可以在一个快照中获得3D断层图像。通过结合各种波长扫描策略，新仪器可以获得高速度和良好的空间分辨率的四维高光谱数据。这些仪器一旦开发出来，可能会对许多行业产生潜在影响，可以对制药、化工、石化或农产品进行无损质量检测。 可以预见的应用包括通过检测假药来改善人类健康，或者用于太阳能电池或微机电系统（MEMS）设备中的3D集成电路芯片的故障分析。宋教授致力于为本科研究人员和K-12学生，未来一代的科学家和工程师提供培训机会。 他还致力于将尖端科学融入课程材料，并积极参与许多校园项目，以招募更多的女性和少数民族学生加入他的团队。宋教授正在开发一种4D近红外吸收和折射率成像，其中波长扫描光源与快照断层扫描技术相结合，该技术由微透镜阵列和数字全息术实现。采用共路设计以进一步提高对环境振动的鲁棒性，并采用空间光调制器以主动补偿色差。对于4-D近红外发射成像，可调带通滤波器或傅里叶变换光谱学与另一种用于发光光的快照断层扫描技术相结合。该理论框架被认为将衍射层析成像的应用扩展到更一般的吸收样本类别，并通过在图像形成和重建模型中包括光的波动性质和部分相干性来提高发射层析成像的准确性。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的评估来支持。影响审查标准。

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Sung at University of Wisconsin-Milwaukee (UWM) develops new instruments for 4-dimensional (4D) chemical imaging in the near-infrared (NIR) range. NIR hyperspectral imaging has been widely used for nondestructive quality inspection; however, existing methods cannot examine a specimen with a complicated internal structure or detect the chemical impurities buried deep inside a 3-D volume because the depth information is lost in the recorded 2-D projection images. Traditional approaches to 3-D tomographic imaging require a scanning mechanism, which significantly increases the data acquisition time and the complexity of an instrument. Professor Sung and his group is developing instruments using a technique called snapshot tomography, which can acquire the 3-D tomogram in a single snapshot. By incorporating various wavelength-scan strategies, the new instruments can acquire the 4-D hyperspectral data at a high speed and good spatial resolution. The instruments, once developed, could potentially impact many industries by allowing nondestructive quality inspection of pharmaceutical, chemical, petrochemical, or agricultural products. Applications such as improving human health by detecting counterfeit medicines or being used in failure analysis of 3-D integrated-circuit chips in solar cells or micro-electro-mechanical system (MEMS) devices are envisioned. Professor Sung strives to provide training opportunities to undergraduate researchers and K-12 students, the future generation of scientists and engineers. He also works on incorporating cutting-edge science into course materials and is actively engaged in many on-campus programs to recruit more women and minority students into his group.Professor Sung is developing a 4D NIR absorption and refractive index imaging where a wavelength-scanning light source is combined with a snapshot tomography technique that is enabled by a micro-lens array and digital holography. A common-path design is incorporated to further increase the robustness to environmental vibrations and a spatial light modulator to actively compensate for the chromatic aberration. For 4-D NIR emission imaging, a tunable bandpass filter or Fourier transform spectroscopy is combined with another snapshot tomography technique for luminescence light. The theoretical frameworks to be developed is believed to extend the application of diffraction tomography to more general classes of absorbing specimens and increase the accuracy of emission tomography by including the wave nature and the partial coherence of light in the image formation and reconstruction models.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.