摘要
通过将窄带法布里-珀罗微腔阵列与可见光探测器焦平面阵列粘贴集成,展示了一种微小紧凑型多光谱成像探测器.通过四次分形组合蚀刻工艺,先在石英基底上获得了以4x4为基本重复单元、共计2048像素×2048像素的微腔滤光阵列;再与探测器芯片贴合后形成了微小型多光谱成像探测器.微区光谱检测表明,微腔阵列样品的响应光谱峰值在520-680 nm之间变化,半峰处的全宽小于10 nm,透过率约70％.可调谐波长单色光合作光源检测表明,该多光谱成像探测器具有16个不同的窄带响应谱;利用光谱通道能清晰分辨目标特征光谱;通过光谱通道图像相减,能有效消除视野中背景,提高目标对比度.它有望应用于皮肤表面观测等辅助诊断,以及逆光条件下目标观测的高动态范围成像等.
Abstract
By designing and fabricating a narrow-band Fabry-Perot multi-beam interference spectroscopic microcavity array,and integrating it with a visible light detector focal plane array,we demonstrate a small compact multispectral imaging detector.The micro-cavity filter array with 4×4 basic repeating units and a total of 2048×2048 pixels is obtained on a quartz substrate by the four-fractal combination lithograph-etching process.Then the micro miniatured multispectral imaging detector is formed by fitting with the detector chip.The depth and precision of the etching will determine the distribution and offset of the central wavelength of the narrowband spectral channel respectively.The results show that the etching rate of reactive ion is(3.6± 0.2)Å/s,and the process is stable and controllable.Due to the different etching depths,the basic repeating unit forms 16 different levels of steps,and the process achieves the design expectation well.The results are obtained as follows:the response spectrum peak of the microcavity array sample varies from 520 to 680 nm,the free spectrum range is 160 nm,the full width at the half-peak is less than 10 nm,the transmittance is about 70％,the relative half-width of the transmittance peak at 590 nm is 1.19％,and the waveform coefficient is 2.78.A 16-channel multispectral camera is constructed by using the optical micro-precision assembly device to realize the precise alignment and the fitting of the micro-cavity filter array and the image sensor.Xenon lamp and monochromator are used as tunable wavelength monochromatic cooperative light source to detect the effect of 16-channel snapshot multispectral imaging on a pixel scale.The results show that the multispectral imaging detector has 16 different narrow-band response spectra.The characteristic spectrum of the target can be clearly distinguished by spectral channel.When imaging the target with known spectral characteristics,for a certain frame of multi-spectral image,selecting a suitable spectral channel can eliminate the background in the field of view through image subtraction and improve the contrast of the target.In the dark room condition,we take the LED light source with center wavelength varying in a range between 528 and 589 nm as the target(the wavelength coincides with the working wavelength of the spectral channel),and effectively suppress the background through the spectral differential intensity subtraction,which can improve the accuracy and sensitivity of the target capture.The 16-channel snapshot multi-spectral imaging detector based on integrated Fabry-Perot microcavity array has the advantages of small size,high integration and strong environmental adaptability,and is expected to play a role in realizing the real-time detection of weak moving targets,auxiliary diagnosis of skin surface observation,and high dynamic range imaging of target observation under backlight conditions.
维普
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