More Like this

1. Fitting Mid-Spatial Frequency Surface Errors with a Rapidly Decaying Fourier Series

   DeMars, Luke A; Rueda, Santiago; Alonso, Miguel A; Suleski, Thomas J (June 2023, Optica Design and Fabrication Congress 2023)

   We apply the Nb=1 solution of the Rapidly Decaying Fourier series to fit mid-spatial frequency surface errors. Using this basis enables definition of sharp spatial frequency bandlimits for mid-spatial frequency specification of optical surfaces. 

   more » « less
2. MSFLib: A Data Library of Mid-Spatial Frequency Surface Errors for Optical Modeling and Specification

   DeMars, Luke; Rueda, Santiago; Suleski, Thomas J (June 2023, Optica Design and Fabrication Congress 2023)

   We describe the development of a data library of mid-spatial frequency surface errors for optical components. This resource enables better understanding of specification of mid-spatial frequency surface errors and their connections to optical performance. 

   more » « less
3. MSFLib: A Data Library of Mid-Spatial Frequency Surface Errors for Optical Modeling and Specification

   DeMars, LukeA; Rueda, Santiago; Suleski, Thomas J (June 2023, Optica Publishing Group)

   We describe the development of a data library of mid-spatial frequency surface errors for optical components. This resource enables better understanding of specification of mid-spatial frequency surface errors and their connections to optical performance. 

   more » « less
4. Optical structuring and finishing toward mid-spatial-frequency error reduction using femtosecond lasers

   https://doi.org/10.1364/OL.520008  

   Chen, Gong; Qiao, Jie (March 2024, Optics Letters)

   We demonstrate nano-structuring and the reduction of mid-spatial-frequency errors using femtosecond laser figuring and finishing. For the first time, to the best of our knowledge, we have corrected mid-spatial-frequency errors from 17 nm to one nanometer in magnitude. We established a method for creating and predicting periodic nanostructures. This demonstration opens the path of using femtosecond lasers to correct surface errors that inherently result from sub-aperture manufacturing techniques. 

   more » « less
5. Annular illumination in 2D quantitative phase imaging: a systematic evaluation

   https://doi.org/10.1364/AO.452325  

   Kulkarni, Pranav_P; Bao, Yijun; Gaylord, Thomas_K (April 2022, Applied Optics)

   Quantitative phase imaging (QPI) is an invaluable microscopic technology for definitively imaging phase objects such as biological cells and optical fibers. Traditionally, the condenser lens in QPI produces disk illumination of the object. However, it has been realized by numerous investigators that annular illumination can produce higher-resolution images. Although this performance improvement is impressive and well documented, the evidence presented has invariably been qualitative in nature. Recently, a theoretical basis for annular illumination was presented by Baoet al.[Appl. Opt.58,137(2019)APOPAI0003-693510.1364/AO.58.000137]. In our current work, systematic experimental QPI measurements are made with a reference phase mask to rigorously document the performance of annular illumination. In both theory and experiment, three spatial-frequency regions are identified: low, mid, and high. The low spatial-frequency region response is very similar for disk and annular illumination, both theoretically and experimentally. Theoretically, the high spatial-frequency region response is predicted to be much better for the annular illumination compared to the disk illumination––and is experimentally confirmed. In addition, the mid-spatial-frequency region response is theoretically predicted to be less for annular illumination than for disk illumination. This theoretical degradation of the mid-spatial-frequency region is only slightly experimentally observed. This bonus, although not well understood, further elevates the performance of annular illumination over disk illumination. 

   more » « less