Fig 2 - uploaded by Pratyasha Sahani
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Transmission spectrum of the color filter in Fabry-Perot configuration as a function of the cavity gap layer thickness. The inset shows the schematic of the gradient thickness optical filter (discussed in text).
Source publication
We propose a pixelized gradient thickness color filter as the compact and space-saving element for achieving simultaneous imaging and spectroscopy using a single image sensor. By replacing the RGB filter integrated in portable devices this can serve the novel purpose on the same platform, and hence makes the device versatile.
Contexts in source publication
Context 1
... thickness of the Ag mirrors is considered as 30nm and the thickness of the intermediate SiO2 layer (cavity gap layer) is chosen to vary in such a way that the peak transmission wavelength spans over the visible wavelength range from 400-700nm.The shift in peak transmission wavelength by varying the thickness of the cavity gap layer is shown in Fig. 2. Fig. 2 shows the transmission spectrum of the FabryPerot optical filter for different values of the cavity gap layer thickness. The spectral characteristic of the filter is obtained numerically by using a commercial software, DiffractMod module of RSoft TM , based on rigorous coupled wave analysis [9]. Material dispersion properties ...
Context 2
... of the Ag mirrors is considered as 30nm and the thickness of the intermediate SiO2 layer (cavity gap layer) is chosen to vary in such a way that the peak transmission wavelength spans over the visible wavelength range from 400-700nm.The shift in peak transmission wavelength by varying the thickness of the cavity gap layer is shown in Fig. 2. Fig. 2 shows the transmission spectrum of the FabryPerot optical filter for different values of the cavity gap layer thickness. The spectral characteristic of the filter is obtained numerically by using a commercial software, DiffractMod module of RSoft TM , based on rigorous coupled wave analysis [9]. Material dispersion properties of the ...
Context 3
... The spectral characteristic of the filter is obtained numerically by using a commercial software, DiffractMod module of RSoft TM , based on rigorous coupled wave analysis [9]. Material dispersion properties of the constituent materials are included in the simulation while evaluating the spectral characteristics of the filter. A glance at Fig. 2 shows that the peak transmission wavelength undergoes red-shift when the cavity gap layer thickness increases which is in accordance with the transmission condition of the Fabry-Perot filter. The filter has a peak transmittance value of ~ 60% and a spectral width of ~ 50nm. In addition, the peak transmittance value decreases as the ...
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... the peak transmittance value decreases as the thickness of the cavity gap layer increases which might be due to thicker SiO2 layer causing more absorption/reflection. The concept of spectral shift of the filter with cavity gap variation is compiled into a single device to obtain gradient thickness optical filter design as shown in the inset of Fig. 2. The gradient thickness optical filter consists of a continuously varying cavity gap layer thickness which will result in a linear variation of the transmission peak of the filter [10]. Thus, by replacing an array of thickness-varying filters with a single filter, the gradient thickness filter can enable novel applications through ...
Citations
... T UNABLE Fabry-Pérot filters (FPFs) have emerged as versatile and indispensable components across a multitude of scientific and industrial fields, including astronomy, metrology, optical communications, nondestructive everyday analysis, medical diagnostics, and environmental monitoring [1], [2], [3], [4], [5], [6], [7], [8]. The advent of tunable FPFs driven by microelectromechanical techniques has significantly advanced the development of complementary metal oxide semiconductor (CMOS)-integrated lab-on-a-chip devices such as miniature spectrometers [9], [10], [11], [12], [13], [14], [15], [16] and hyperspectral imaging systems [17], [18], [19], [20]. ...
A tunable air-gap Fabry–Pérot filter consisting of distributed Bragg reflectors as cavity mirrors was developed to operate in the visible wavelength range. The wavelength tunability of the filter was achieved based on the piezo actuation mechanism. Four in-plane identical piezo actuators were employed to simultaneously achieve both wavelength tunability and cavity air-gap parallelism in the filter. Two pairs of piezo actuators positioned at crossed locations enabled independent control of cavity air-gap dimensions along orthogonal directions in the cavity plane. Optical transmission measurements were performed at different spatial positions on the cavity region to estimate the cavity air-gap dimensions. The initial maximum spectral separation among different spatial positions owing to the initial non-parallelism of the cavity air gap was estimated to be ∼28 nm. After achieving cavity air-gap parallelism via piezo actuation, the final maximum spectral separation was reduced to ∼3 nm. The proposed device configuration significantly improved the cavity air-gap parallelism by minimizing the maximum variation of the cavity air-gap dimension from an initial value of 535 nm to a final value of 18 nm, resulting in an improvement by a factor of ∼30. This device prototype can enable high-resolution and high-throughput spectral transmission with improved spatial uniformity across a large cavity area, showing great promise for advancing hyperspectral imaging systems.
