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This paper presents a method for instantaneous measurement of Fabry-Parot(F-P) transmittance curve. Compared with the previous method, this method has many advantages, such as scanning-free, simple in structure and accuracy.

The geometric error of long-stroke five-axis machine tools will greatly affect the machining accuracy, which needs to be identified and compensated. This paper proposed a method based on screw theory to identify Position independent geometric errors (PIGEs) and present a method to analyze the sensitivity of each twist error vector. Compared with the model base on homogeneous transformation matrices (HTMs), the screw theory-based kinematic model avoids the local frame and the singularity problem. This paper also refines the algorithm by adding constraints to improve the identification accuracy. The proposed error identification method is verified through simulation and experiment with Etalon Laser Tracer on a five-axis machine tool.

We create a rate equation theoretical model of a continuous-wave end-pumped Pr3+:YLF SLM laser that characterizes the output properties of a single-longitudinal-mode (SLM) green laser. After inserting two Fabry–Perot (F–P) etalons with thicknesses of 0.3 mm and 0.5 mm and angles of 1.42° and 0.69° into the cavity, a single-longitudinal-mode green laser was generated. The maximum output power in single-longitudinal mode was 183 mW. The maximum absorbed pump power was 6.2 W. The corresponding linewidth is about 18 MHz. This work presents a simple method for generating a single-longitudinal-mode laser in the green spectral region, providing a practical approach for various green-laser-related applications.

We developed an immunoassay for mouse immunoglobulin (IgG) quantitation using poly( N -isopropylacrylamide- co -acrylic acid) (pNIPAm- co -AAc) microgel-based etalon devices. To achieve this, a biotinylated primary antibody specific to mouse IgG was immobilized on the top Au layer of an etalon device via its interaction with a streptavidin-modified etalon surface. Mouse IgG captured on the etalon surface from the solution was quantified using an HRP-conjugated secondary antibody. HRP catalyzed the oxidation of 4-chloro-1-naphthol (4CN) to form insoluble 4-chloro-1-naphthon (4CNP), resulting in a concentration change of 4CN in solution. The etalon was able to detect the 4CN concentration change by monitoring the extent of the etalon’s reflectance peak shift, which allows the quantitation of mouse IgG. The etalon-based assay can detect mouse IgG down to 0.018 nM with a linear range of 0.02–5 nM. Graphical abstract

Fiber-based interferometers receive significant interest as they lead to miniaturization of optoacoustic and ultrasound detectors without the quadratic loss of sensitivity common to piezoelectric elements. Nevertheless, in contrast to piezoelectric crystals, current fiber-based ultrasound detectors operate with narrow ultrasound bandwidth which limits the application range and spatial resolution achieved in imaging implementations. We port the concept of silicon waveguide etalon detection to optical fibers using a sub-acoustic reflection terminator to a Bragg grating embedded etalon resonator (EER), uniquely implementing direct and forward-looking access to incoming ultrasound waves. Precise fabrication of the terminator is achieved by continuously recording the EER spectrum during polishing and fitting the spectra to a theoretically calculated spectrum for the selected thickness. Characterization of the EER inventive design reveals a small aperture (10.1 µm) and an ultra-wide bandwidth (160 MHz) that outperforms other fiber resonators and enables an active detection area and overall form factor that is smaller by more than an order of magnitude over designs based on piezoelectric transducers. We discuss how the EER paves the way for the most adept fiber-based miniaturized sound detection today, circumventing the limitations of currently available designs. The authors embed a micro-resonator in a 10 µm core fiber, which enables ultrasound wave detection with large bandwidth and small aperture. This facilitates high-resolution optoacoustic (photoacoustic) imaging and ultrasonography.

Conventional interferometers provide uniform phase sensitivity across the measurement range. However, for applications involving small phase changes, amplifying the response within a specific phase range—at the expense of reduced sensitivity elsewhere—can be advantageous. A key example is the Gires-Tournois etalon, used in gravitational wave interferometers. In this work, we introduce an ultrasensitive phase measurement system based on time-holographic recording with a conventional Mach-Zehnder interferometer, operated near the intensity minimum at the dark output port. Phase fluctuations in the milliradian range around this point are converted into rad-sized dark output phases, with amplification factors exceeding 1,000. The adjustable imbalance between the interferometer arms controls this magnification, which is revealed by heterodyning the output with a frequency-shifted beam. Phase is digitally retrieved from the time-hologram using Fourier processing, with noise subtraction for correction. The system achieves phase sensitivities better than λ/3,000, enabling sub-nanometer precision for dimensional measurements. This versatile platform provides powerful tools for ultrasensitive phase measurements in a wide range of scientific and technological applications.

This paper proposes a self-calibration method for lens focal length measurement based on a Fabry-Pérot (F-P) etalon, and investigates uncertainty evaluation strategies in scenarios where measurement errors affect the results through indirect propagation. In the measurement method, the relationship between the diameters of interference rings and interference orders in area-array images is utilized, and the relative focal length is calculated using the least squares method. For uncertainty analysis, evaluation models suitable for both the Guide to the Expression of Uncertainty in Measurement (GUM) method and the Monte Carlo method (MCM) are established. In the Monte Carlo method, error propagation approaches are specifically studied for defocus error and pixel pitch error in focal length measurement. The results show that the GUM evaluation method fails to pass validation by MCM, mainly because the distribution of the relative focal length deviates from the t-distribution assumption. Furthermore, this study proposes an uncertainty evaluation process applicable to such indirect measurement models, which provides a valuable reference for complex optical measurement systems.

We established a theoretical model of the multi-wavelength Pr:YLF laser at 604 nm, 607 nm and 639 nm based on the F-P etalon and studied the influence of the F-P etalon insertion angle on the threshold power of different wavelength lasers. The theoretical results show that by adjusting the insertion angle of a single F-P etalon, direct visible multi-wavelength laser output with different combinations can be achieved. Based on the guidance of theoretical parameters, we obtained maximum output powers of 729 mW, 420 mW, 382 mW, and 269 mW for single-wavelength at 639 nm, dual-wavelength at 604 nm&639 nm, 607 nm&639 nm, and triple-wavelength at 604 nm&607 nm&639 nm lasers, respectively, in the experiment. The experimental results agree well with the simulation. This method effectively simplifies the resonator structure and improves the conversion efficiency, providing a theoretical basis for guiding and optimizing the design of multi-wavelength laser. Such a visible multi-wavelength integrated laser source will have potential applications in fields such as laser medicine, color displays, and deep ultraviolet generation.

To obtain single-longitudinal-mode (SLM) laser output under high power injection conditions, a theoretical model of multi-mode rate equation based on pre-laser Q-switched and a Fabry–Perot (F-P) etalon group is established in this research. The simulation results show that with the combination of three F-P etalons, not only can the spectral linewidth be initially narrowed, but the transmission loss difference between adjacent longitudinal modes can also be further adjusted. Therefore, the longitudinal mode selection ability of the pre-laser Q-switch under high-power energy injection is effectively enhanced. In the experiment, dynamic modeling is used as a key parameter guide. The final stable output 639.7 nm Pr:YLF SLM laser was obtained. The upper limit of pump absorption was effectively increased by 57%, the single pulse energy was increased by 56%, and the linewidth was compressed to 14 MHz. The experimental results are in good agreement with the simulation results.

We describe the construction of a continuous 38-year record of stratospheric aerosol optical properties. The Global Space-based Stratospheric Aerosol Climatology, or GloSSAC, provided the input data to the construction of the Climate Model Intercomparison Project stratospheric aerosol forcing data set (1979–2014) and we have extended it through 2016 following an identical process. GloSSAC focuses on the Stratospheric Aerosol and Gas Experiment (SAGE) series of instruments through mid-2005, and on the Optical Spectrograph and InfraRed Imager System (OSIRIS) and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data thereafter. We also use data from other space instruments and from ground-based, air, and balloon borne instruments to fill in key gaps in the data set. The end result is a global and gap-free data set focused on aerosol extinction coefficient at 525 and 1020 nm and other parameters on an “as available” basis. For the primary data sets, we developed a new method for filling the post-Pinatubo eruption data gap for 1991–1993 based on data from the Cryogenic Limb Array Etalon Spectrometer. In addition, we developed a new method for populating wintertime high latitudes during the SAGE period employing a latitude-equivalent latitude conversion process that greatly improves the depiction of aerosol at high latitudes compared to earlier similar efforts. We report data in the troposphere only when and where it is available. This is primarily during the SAGE II period except for the most enhanced part of the Pinatubo period. It is likely that the upper troposphere during Pinatubo was greatly enhanced over non-volcanic periods and that domain remains substantially under-characterized. We note that aerosol levels during the OSIRIS/CALIPSO period in the lower stratosphere at mid- and high latitudes is routinely higher than what we observed during the SAGE II period. While this period had nearly continuous low-level volcanic activity, it is possible that the enhancement in part reflects deficiencies in the data set. We also expended substantial effort to quality assess the data set and the product is by far the best we have produced. GloSSAC version 1.0 is available in netCDF format at the NASA Atmospheric Data Center at https://eosweb.larc.nasa.gov/. GloSSAC users should cite this paper and the data set DOI (https://doi.org/10.5067/GloSSAC-L3-V1.0).