Dr. Dongdong Fan Profile

Dr. Dongdong Fan

at Tsinghua Univ

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Author

Publications (2)

Proceedings Article | 16 June 2003 Paper

Compact computed-tomography imaging spectrometer

Dongdong Fan, Minxian Wu, Jiangang Wang, Haoyun Wei

Proceedings Volume 4897, (2003) https://doi.org/10.1117/12.467329

KEYWORDS: Spectroscopy, Expectation maximization algorithms, Binary data, Calibration, Reconstruction algorithms, Charge-coupled devices, Optical design, Imaging systems, Data acquisition, Spectral calibration

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Proceedings Article | 25 September 2001 Paper

Computed tomography imaging spectrometer by using a novel hybrid diffractive-refractive element

Dongdong Fan, Minxian Wu, Qingsheng He, Tao Yong, Haoyun Wei

Proceedings Volume 4548, (2001) https://doi.org/10.1117/12.441370

KEYWORDS: Computed tomography, Spectroscopy, Prisms, Imaging spectroscopy, Imaging systems, 3D image processing, Sensors, Charge-coupled devices, Holography, Remote sensing

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The multi-spectal or hyper-spectral imager provides three dimensional description for spatial and spectral intensity distribution of objective scenes and it can be a powerful tool for remote sensing in much application. There are several approaches to collection three dimensional data cube of image, and most of them require a scanning mechanism. Therefore those methods are difficult to record both spectral and spatial information of a dynamic scene such as a missile in flight, changing rapidly red tide, and so forth. Computed Tomography Imaging Spectrometer (CTIS) is a new branch application of computed tomography technology. The CTISs with different type configuration have been reported by a few of author. Two main types of CTISs are proposed. One is to use the two dimension gratings like Dammann gratings, the two 1-D gratings placed in orthogonal way, or three 1-D gratings separated by 60 degree. Due to its temporally and spatially non-scanning technique, this type is capable of capturing the flash events and can be used for instantaneous spectral imaging. The main problem of these CTISs is that the diffractive efficiencies are not only depended on the various wavelength but also on the different diffractive orders. That will effect the reconstruction algorithm and its results. These problems lead to reduce the signal to noise and dynamic range of spectral imaging system. The other is to take the approaches such as rotational spectro-tomography, or grating combined with a rotational direct-view prism. The advantages of these approaches are a)high throughput and b)easy to obtain more uniform data of different projection, but its disadvantage is obvious that the moving parts must be adopted. In our work, a principle and configuration of CTIS is indicated, and especially, a novel hybrid diffractive-refractive element is proposed, which is a combination of an array of optical prisms and one dimension holographic gratings. It can provide the uniformity of performance of projection data in different directions. As a result of high throughput and non-scanning parts, it can collect transient spectral imaging. Furthermore this grating is easily fabricated relatively. The capability enables it to be a prospect of applications in variety of application fields. This type of CTIS with the novel hybrid diffractive-refractive element is designed.

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