Development of measurement system and analysis method for characterization of linear variable bandpass filters

Abstract

An automated measurement system was developed to characterize the spatial gradient, linearity of the spatial gradient, bandwidth and transverse uniformity of a linear variable filter (LVF). To demonstrate this, the LVF fabricated in our group has been measured and analyzed. Simulations for beam spot size effects on measurements were performed for various LVF spectral peak profiles with results indicting significant averaging effect due to beam spot size and this is consistent with experiment results. Moreover, to fit the peak profile more accurately, a modified Pearson VII function was proposed and demonstrated high capability to express complex shapes of peaks mathematically. This provides a methodology for deconvoluting the original LVF peak profile from a measured averaged peak profile and has been verified using actual measured data.

Linear Variable PbS-DMSO Filter with Potentiality for Hyperspectral Imaging Applications

“…The current mainstream preparation scheme of array QD filters was to prepare QDs of various sizes and materials through chemical synthesis, thereby regulating and controlling the bandgap and absorption range of QDs and achieving filtering characteristics in a wide spectral range. A variety of QDs of various materials have been developed, including CdS, CdSe, PbS, PbSe, perovskite, etc., matched different filtering spectral ranges of UV or Vis or NIR. − However, there are a number of shortcomings with such array QD filters: First, in order to obtain the QDs with different absorption characteristics, hundreds of QD chemical synthesis works must be carried out to obtain QDs of different sizes or different materials. , Moreover, due to the limited number of filter channels in array QD filters, they cannot match the high integration and resolution of current signal processors, which greatly limits the acquisition of spectral information. − Therefore, unlike the traditional array QD filters, we hope to develop a novel QD filter with linear continuous filtering capability that can cover a wide spectral range while omitting hundreds of different QD chemical synthesis works …”