Extended depth-of-focus (EDOF) diffractive lenses produce a narrow and long focusing region which have many applications on microscopy, laser focusing or contact and intraocular lenses. Several designs have been proposed to achieve EDOF by angularly modulating the focal length. Nevertheless, when the focus is highly elongated, some undesired intensity fluctuations are produced. To solve this problem, we have generalized this type of lenses by defining their focal length as a Fourier series. Moreover, we have used Particle Swarm Optimization algorithm to optimize its Fourier series coefficients and generate an enhanced design. The performance of our Fourier Series Diffractive Lens (FSDL) is parameterized through the Full Width at Half Maximum (FWHM) of the beam and the uniformity of the intensity along the optical axis. Our results prove that the FSDL beam on the focal region is narrower and much more uniform than previous EDOF designs, showing the enhancement of the proposed EDOF lens.
Spatial light modulator is an essential electro-optical device in applications that require to modulate the amplitude, phase, or polarization of light. Its proper use requires to determine its Mueller matrix. In this work, we compare different methods to calculate the condition number of Mueller-Stokes polarimetry techniques, which defines their maximum relative error. Combining experimental and calculated values, we determined the most suitable method for calculating the condition number.
The real-time monitoring of physical and chemical parameters in running fluids is of importance for biomedical, biochemical, and environmental applications, such as the presence of biomarkers or chemomarkers, or the departure from some preset values of critical parameters. In this contribution we present a new generation of Permeable Diffractive Optical Elements (PDOE) based on photon sieves. In brief, the PDOE is made of passing holes properly placed on specific locations on a rigid surface. This arrangement makes PDOEs ideal to work with running fluids. Our PDOE is optimized maximizing the irradiance at is focal plane, maintaining an appropriate permeability ratio. The starting point is the classical Fresnel zone distribution. We have used two different optimization strategies to design a working PDOE: i) Particle Swarm Optimization has been applied to modify the distribution of holes on the PDOE simultaneously considering all of them; ii) an iterative minimization algorithm adding one hole at the time until filling the PDOE aperture. Both optimization algorithms generate focal spots that are compared to choose the design better suited for the proposed application. Once the PDOE is optimized and fabricated, the surface of the remaining rigid structure is nanostructured (for example using Laser Induced Periodic Surface Structures), or functionalized, to provide specific sensing capabilities. In addition, the PDOE is integrated within a pipe where the fluid under analysis circulates through. A proposal for the optoelectronic assembly of the device-including auxiliary optical elements, light sources, and detectors - is also presented in this contribution.
We designed, fabricated and tested a Vector Diffractive Optical Element (VDOE) to simultaneously determine the Stokes vector of light. It comprises several sectors. Each one is a vector Fresnel zone plate which focuses the light on separate foci and has different polarization properties. The polarization state is calculated from their intensities.
From simulations, we could identify the error sources that were analytically removed. The residual uncertainty after applying our corrections was as low as 6x10^(-5). The uncertainty obtained for our fabricated VDOE, 3.33 %, is competitive with the results from state-of-the-art techniques.
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