ABSTRACT
A detailed theoretical model is provided to analyze the effects of temperature on prism-based surface plasmon resonance (SPR) sensors, including temperature dependence of the metal and prism. A complete sensitivity matrix simultaneously measures variations in refractive index (RI) and temperatures using measurements at two wavelengths for the angular-interrogation mode, or at two angles of incidence for the wavelength-interrogation mode. Correction of matrix coefficients improves accuracy of the two modes. Validation is performed using a self-designed wavelength SPR system with an adjustable incident angle perform. This method provides a new way to detect the RI and may lead to the better design and fabrication of prism-based SPR sensors.
ABSTRACT
In numerous applications of optical scanning microscopy, a reference tapered fiber lens with high symmetry at sub-wavelength scale remains a challenge. Here, we demonstrate the ability to manufacture it with a wide range of geometry control, either for the length from several hundred nanometers to several hundred microns, or for the curvature radius from several tens of nanometers to several microns on the endface of a single mode fiber. On this basis, a scanning optical microscope has been developed, which allows for fast characterization of various sub-wavelength tapered fiber lenses. Focal position and depth of microlenses with different geometries have been determined to be ranged from several hundreds of nanometers to several microns. FDTD calculations are consistent with experimental results.
ABSTRACT
The wavelength calibration research on the automatic grating monochromator for orthogonal Czerny-Turner structure was investigated. Combined with the structure parameters and characteristic of this monochromator, the sinusoid that accords with the grating equation was proposed as the function of the wavelength calibration. Based on the principle of the least square method, the formula of the fitting residual error of the wavelength calibration was given. Using the Nelder-Mead simplex method, the undetermined coefficient of the fitting residual error was solved, which founded the precise formula between the wavelength and the grating turning angle. The accuracy of the method was verified through the experiment. The calibrated wavelength precision of the monochromator is less than 0.1 nm, which satisfies the application requirement. Applied in the wavelength calibration of the automatic grating monochromator with orthogonal Czerny-Turner structure, this method is simple to apply and easy for implementation. Using this method, the wavelength calibration can be realized quickly and real-timely, but it is only needed to modify the control program of the stepping motor slightly, which shows a better practicability.
ABSTRACT
The plane grating double monochromator is the important part of the instrument for testing diffraction efficiency of plane grating, and in order to accomplish the research of the instrument, the optical system design and simulation of the plane grating double monochromator was investigated. The instrument mainly consists of light source, front monochromator, testing monochromator and detector, and combined with the practical requirement, the corresponding light source, detector and the structure of the optical path were selected. According to the design requirement, the design and simulation of the optical system of the front monochromator and testing monochromator were done respectively, and the spot diagram of the image surface and the results of real ray trace were given. The analysis showed that in the front monochromator the maximum width of the exit spot and the maximum height of the exit spot were 0.33 and 1.83 mm respectively. On the other hand, in the testing monochromator, the maximum width of the exit spot and the maximum height of the exit spot were 0.66 and 7.27 mm, respectively. Through selecting the size of the exit slit properly, the system can work without luminous flux lost, which guarantees the testing precision of the optical system of the instrument.
