Large-aperture System Research Articles

Full-aperture extended-depth oblique plane microscopy through dynamic remote focusing.

The reprojection setup typical of oblique plane microscopy (OPM) limits the effective aperture of the imaging system, and therefore its efficiency and resolution. Large aperture system is only possible through the use of custom specialized optics. A full-aperture OPM made with off the shelf components would both improve the performance of the method and encourage its widespread adoption. To prove the feasibility of an OPM without a conventional reprojection setup, retaining the full aperture of the primary objective employed. A deformable lens based remote focusing setup synchronized with the rolling shutter of a complementary metal-oxide semiconductor detector is used instead of a traditional reprojection system. The system was tested on microbeads, prepared slides, and zebrafish embryos. Resolution and pixel throughput were superior to conventional OPM with cropped apertures, and comparable with OPM implementations with custom made optical components. An easily reproducible approach to OPM imaging is presented, eliminating the conventional reprojection setup and exploiting the full aperture of the employed objective.

The implementation of temporal synthetic aperture imaging for ultrafast optical processing

A new technique of temporal imaging, called temporal synthetic aperture imaging (TSAI), is proposed to achieve higher time resolution of the imaging system for ultrafast optical processing. The proposed technique combines several of independent small-aperture systems together to get a higher time resolution and better image quality as a large-aperture system. It can solve the problem that an oversized aperture time lens is difficult to achieve in practice. In this paper, after analyzing the filtering effect, a novel implementation method of TSAI is presented. In order to verify the correctness, we demonstrate a decuple magnification of a signal with two 1ps width pulse separated 2ps, using a synthetic aperture by the system simulation.

Imaging and image restoration of lens-combined modulated wavefront coding.

In this paper, it presents a new wavefront coding (WFC) technology that we call lens-combined modulated wavefront coding (LM-WFC). Based on the LM-WFC design method, we establish a large depth of field and large aperture system. Simulation results indicate that the modulation transfer function of the system has a defocus invariant characteristic, which all typical WFC systems have, with a large depth of field. Experimental results for comparing the LM-WFC imaging system and a traditional imaging system are presented. The comparative results demonstrate that the LM-WFC system has an imaging performance invariant over a wide depth of field range.

Highly uniform parallel microfabrication using a large numerical aperture system

In this letter, we report an improved algorithm to produce accurate phase patterns for generating highly uniform diffraction-limited multifocal arrays in a large numerical aperture objective system. It is shown that based on the original diffraction integral, the uniformity of the diffraction-limited focal arrays can be improved from ∼75% to >97%, owing to the critical consideration of the aperture function and apodization effect associated with a large numerical aperture objective. The experimental results, e.g., 3 × 3 arrays of square and triangle, seven microlens arrays with high uniformity, further verify the advantage of the improved algorithm. This algorithm enables the laser parallel processing technology to realize uniform microstructures and functional devices in the microfabrication system with a large numerical aperture objective.

Convex Aspherical Surface Testing Using Catadioptric Partial Compensating System

Aspheric optical components are the indispensable part of modern optics systems. With the constant development of aspheric optical fabrication technique, the systems with large aperture convex aspheric optical components are widely used in astronomy and space optics. Thus, the measurement of the figure error of the whole convex aspherical surface with high precision comes to be a challenge in the area of optical surface manufacture, and surface testing method is also very important. This paper presents a new partial compensating system by the combination of a refractive lens and a reflective mirror for testing convex aspherical surface. The refractive lens is used to compensate the aberration of the tested convex asphere partially. The reflective mirror is a spherical mirror which is coaxial to the refractive lens and reflecting the lights reflected by the tested convex asphere back to the convex asphere itself. With the long focal length and large aperture system we can realize a lighter and more compact system than the refractive partial compensating system because the spheric reflective mirror is more easily to realize and can bending the light conveniently.

Large-aperture system for high-resolution 180° electron scattering

A new system for 180° electron scattering has been put into operation at the superconducting Darmstadt linear electron accelerator S-DALINAC, using a large-aperture QCLAM spectrometer. The properties of the spectrometer allow for high-resolution 180° measurements with a larger momentum acceptance than that of any previous 180° system, together with unprecedented capabilities for solid angle definition as well as for alignment and monitoring of the system. The large angular acceptance and the precise angular definition allow the solid angle acceptance of the system to be specified by software cuts after the data have been taken, permitting the appropriate balance between maximum statistical precision and maximum longitudinal-to-transverse suppression ratio.

Compton scattering in a large-aperture positron imaging system

Compton scattering of gamma rays within the image volume has been assessed for a large-aperture positron-emission-tomography imaging system. The Compton scattered attenuation and the Compton scattered background were both modeled and measured for point sources centered in scattering spheres up to 10 cm in diameter. Good agreement was obtained between simulations and measurements. The attenuation problem is independent of the detector system, but its correction is more difficult in a large-aperture system. The scattered coincidence background is large in this system (43% for a 10-cm-diameter scattering sphere), but the background overlap is reduced with 3D imaging.

Large Objective for Night Observation

A relatively large (23-cm) aperture system working at f/1.5 has been designed for low-light-level application. A catadioptric system, utilizing only spherical surfaces as described by M. Shenker, serves as a starting point. It consists of three large correctors in front of the primary, and a single element located near the focal plane. All elements are made of BK-7 glass. The system presented incorporates one of the large corrector elements with the primary to form a Mangin mirror, and the secondary has been made coincident with the rear surface of the second element. A different glass has been selected for this objective, yielding a system with improved performance, greater rigidity, and higher transmittance. The optical evaluation, thermal properties, and mechanical mounting are reported with a comparison of the theoretical and actual performance.