Wenmin Wu

Research of a computed-tomography imaging interferometer

This paper presents a novel imaging spectrometer, the Computed-Tomography Imaging Interferometer (CTII). CTII is the combination of the conventional Fourier Transformation Imaging Spectrometer (FTIS) and the Computed-Tomography Imaging Spectrometer (CTIS).This system consists of a telescope system, a collimating system, a Dove prism, a cylindrical lens, a Michelson interferometer, and a focal plane array sensor. Therefore, CTII retains the advantages of both FTIS and CTIS such as high etendue, high spectral resolution and the snapshot ability. In this paper, the basic principle of CTII is introduced. And the experimental system of a CTII is constructed. The experimental results show CTII is feasible.

Measuring spatially varying, multispectral, ultraviolet bidirectional reflectance distribution function with an imaging spectrometer

Abstract. The bidirectional reflectance distribution function (BRDF) data in the ultraviolet (UV) band are valuable for many applications including cultural heritage, material analysis, surface characterization, and trace detection. We present a BRDF measurement instrument working in the near- and middle-UV spectral range. The instrument includes a collimated UV light source, a rotation stage, a UV imaging spectrometer, and a control computer. The data captured by the proposed instrument describe spatial, spectral, and angular variations of the light scattering from a sample surface. Such a multidimensional dataset of an example sample is captured by the proposed instrument and analyzed by a k-mean clustering algorithm to separate surface regions with same material but different surface roughnesses. The clustering results show that the angular dimension of the dataset can be exploited for surface roughness characterization. The two clustered BRDFs are fitted to a theoretical BRDF model. The fitting results show good agreement between the measurement data and the theoretical model.

Fast ARFTIS reconstruction algorithms using CUDA

In order to realize the fast reconstruction processing of all-reflective Fourier Transform Imaging Spectrometer (ARFTIS) data, the authors implement reconstruction algorithms on GPU using Compute Unified Device Architecture (CUDA). We use both CUDA 1DFFT library and customization CUDA parallel kernel to accelerate the spectrum reconstruction processing of ARFTIS. The results show that the CUDA can drive hundreds of processing elements (‘manycore’ processors) of GPU hardware and can enhance the efficiency of spectrum reconstruction processing significantly. Farther, computer with CUDA graphic cards will implement real-time data reconstruction of ARFTIS alone.

Realization of Fourier transform imaging spectrometer based on all-reflective optics

We present our latest research development of the all-reflective Fourier transform imaging spectrometer based on the principle of wavefront-splitting interference. The optical configuration of this system includes a set of Fresnels double mirrors and a number of other reflective telescopes or mirrors. The major advantages of this system includs higher optical throughput, larger spectral bandwidth, and less chromatic aberration as compared with conventinal chromatic-despersion imaging spectrometer . In this paper ,the optical principle and the prototype device of our system are introduced, and the latest experimental results from our prototype device are presented.

Writing trace identification using ultraviolet Fourier-transform imaging spectroscopy technique

Conventional identification methods of writing traces commonly utilize imaging or spectroscopic techniques which work in visible to near infrared range or short-wave infrared range. Yet they cannot be applied in identifying the erased writing traces. In this study, we perform a research in identification of erased writing traces applying an ultraviolet Fouriertransform imaging spectrometer. Experiments of classifying the reflected ultraviolet spectra of erasable pens are made. The resulting hyperspectral images demonstrate that the erased writing traces on printing paper can be clearly identified by this ultraviolet imaging spectrometer.

Simulation study of the computed tomography Fourier transform imaging spectrometer using a Sagnac interferometer

We introduce our latest research of the computed tomography Fourier transform imaging spectrometer that combines the advantages of both the computed tomography imaging spectrometer and the Fourier transform imaging spectrometer. In our previous work, there were still some problems such as the optical aberration in the optical system. Therefore, some significant improvements are made on the optical configuration of our new system. In this paper, the computational simulation of our new system is introduced. Both the interferogram-projection cube and the spectrum-projection cube are generated in the simulation experiment, and the filtered back projection algorithm is adopted in the image reconstruction. The results of the simulation demonstrate the feasibility of our new system.