Surface plasmon (SP) is widely used in biosensing. There are generally two configurations for SP excitation: the prismcoupled and objective-coupled configurations. However, both configurations show limitations in SP excitation. We propose a non-spherical super-lens for SP excitation. It features on: 1) simple configuration without the aid of objectives; 2) allowing 2-D excitation; 3) low cost. We elaborate the design concept and the designed profile. To the best of our knowledge, this is the first time to propose this specific lens for SP excitation.
Phase retarders (PRs) are space-variant waveplate elements which are usually utilized to generate radial and azimuthal polarization and find the polarization axis. So far, there have been mainly two types of phase retarders: half-wave phase retarder and quarter-wave phase retarder. Their principles are similar while functions are different. Some researchers may feel confused to make a choice between them. The present work aims to provide an engineering reference for choosing phase retarders with half-wave and quarter-wave retardation in practical applications. We make a comparison of the two types of PRs in both principles and applications to show their properties clearly.
Radial polarization (RP) and azimuthal polarization (AP) components in vector vortex beams own orthogonal polarization directions and are different in many functions. Thus, the splitting of AP and RP is required in detailed applications. This work presents to split a vector vortex beam into AP and RP by using a highly commercial S-waveplate. This approach is simple and the light losses are low. The configurations and principle of this approach are elaborated.
Radial polarization (RP) and azimuthal polarization (AP) of vector beams differ in many applications, and thus the splitting of the two polarization modes is highly required in many scenarios. Considering that there has been no specific and commercial device for RP/AP beam splitting, this work presents a simple and compact approach for the splitting by use of a commercial-access polarization axis finder (PAF). The configuration on how to implement the approach is elaborated.
Polarization purity is an important indicator for both radial polarization (RP) and azimuthal polarization (AP) beams. This work presents a simple and compact approach to measure the RP/AP purity. It is implemented by using a polarization axis finder (PAF) and two half-wave plates. This measurement approach is easy to implement and all of the involved devices are commercialized.
Surface plasmon microscopy (SPRM) usually employs high refractive index prism or high numerical aperture (NA) objective as coupling device to excite surface plasmon. Here we apply high NA oil-immersion objective considering k vector conditions of SPs and localization of SPs which provides better lateral resolution and less cross-talk between adjacent areas. However, performance of an objective based SPRM is often limited by the finite aperture of a physical objective which corresponds to sudden transition and limited bandwidth. Here we give a simplified model of the SPRM and numerically calculate how the sudden transition on the clear aperture edge causes inherent error. Notch filtering algorithm is designed to suppress the noisy ripples. Compared to the pupil function engineering technique, this technique makes both the sacrifice of NA and utilization of spatial light modulator unnecessary and provides a more compact system setup without decreasing the resolution and contrast.
Biology and medicine sample measurement takes an important role in the microscopic optical technology. Optical tweezer has the advantage of accurate capture and non-pollution of the sample. The SPR(surface plasmon resonance) sensor has so many advantages include high sensitivity, fast measurement, less consumption of sample and label-free detection of biological sample that the SPR sensing technique has been used for surface topography, analysis of biochemical and immune, drug screening and environmental monitoring. If they combine, they will play an important role in the biological, chemical and other subjects. The system we propose use the multi-axis cage system, by using the methods of reflection and transmiss ion to improve the space utilization. The SPR system and optical tweezer were builtup and combined in one system. The cage of multi-axis system gives full play to its accuracy, simplicity and flexibility. The size of the system is 20 * 15 * 40 cm3 and thus the sample can be replaced to switch between the optical tweezers system and the SPR system in the small space. It means that we get the refractive index of the sample and control the particle in the same system. In order to control the revolving stage, get the picture and achieve the data stored automatically, we write a LabVIEW procedure. Then according to the data from the back focal plane calculate the refractive index of the sample. By changing the slide we can trap the particle as optical tweezer, which makes us measurement and trap the sample at the same time.
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