Transmission structured illumination microscopy with tunable frequency illumination using tilt mirror assembly

So far, all our studies have been based on the paraxial approximation described in Section 2.4. This approximation holds for an imaging lens (objective) whose numerical aperture is not large, in which case many effects such as apodization, depolarization and aberration can be ignored. When the numerical aperture of a lens becomes approximately larger than 0.7, these effects become pronounced and must be included in the imaging theory. This chapter is devoted to the study of imaging with a high numerical-aperture objective. After the effects of a high numerical-aperture objective are described in Section 6.1, the Debye imaging theory for a high numerical-aperture objective, which has been mentioned in Section 2.3, is presented in Section 6.2. From the Debye theory, apodization, one of the effects related to a high numerical-aperture objective, is studied in detail in Section 6.3. Transfer functions under the Debye theory are derived in Section 6.4. The vectorial diffraction theory for a high numerical-aperture objective in a uniform medium is presented in Section 6.5. The focusing of a high numerical-aperture objective through dielectric interfaces is discussed in Section 6.6.

We report the method of producing a spatio-temporal (ST) wave packet carrying pure transverse orbital angular momentum (OAM) with subwavelength spatial sizes. Due to the lack of temporal focusing, an ST wave packet focused by a high numerical aperture (NA) objective lens experiences a "spatio-temporal astigmatism" effect similar to the focusing action of a cylindrical lens on the transverse profile of optical field. Thus an ST vortex with a spiral phase in the ST domain focused through a high NA objective will be distorted and lose the ST characteristic spiral phase pattern. With the understanding of such an ST astigmatism, the ST wave packet can be pre-conditioned such that an ST vortex carrying OAM with subwavelength transverse sizes can be obtained after strong focusing. This is the first revelation that a tightly focused ST vortex beam with transverse OAM can be realized, paving the way for potential applications including microscopy, optical trapping, laser machining, nonlinear light-matter interactions, and so on. The ST astigmatism effect also offers insights for the focusing and propagation studies of other types of ST wave packets.

Hybrid-type 3-axis actuator for active tilt compensation in optical pickup

Despite the recent development of advanced ophthalmic imaging techniques, volumetric fluorescence angiography (vFA) over a large field of view is still lacking. Fundus photography techniques have significant limitations due to the lack of 3D imaging capability. Scanning laser ophthalmoscopy (SLO) and confocal SLO (cSLO) use confocal gating to remove diffused light, resulting in crisper image quality. However, the volumetric imaging of SLO requires to compile z stacks, which can be challenging and time-consuming. Adaptive optics SLO (AOSLO) allows diffraction-limited resolution in both axial and lateral resolution. This technique is limited however, by its small field of view (FOV) and also the necessity of z stacks for volumetric imaging. To fill the technical void of vFA over a large field of view (FOV), we developed a novel retinal imaging modality called oblique scanning laser ophthalmoscopy (oSLO) for in vivo volumetric fluorescence retinal imaging. By using oblique illumination and detection, oSLO essentially allows "OCT-like" cross-sectional images contributed solely by the fluorescent contrast, without the need for z stacking. We will demonstrate 3D vFA over a 30˚x30˚ FOV in vivo in mouse retina. We will further report a high-speed oSLO in imaging capillary hemodynamics. The new capability allows the calculation of capillary hematocrit and blood speed in 3D, which can be potentially valuable in diabetic retinopathy and macular degeneration.

We present a robust objective lens optimized for applications requiring both high numerical aperture (NA) and long front working distance imaging, comprised of all commercial-off-the-shelf (COTS) spherical singlet lenses. Unlike traditional designs that require separate collimation and refocusing stages, our approach directly converges imaged light to the back focal plane using a single lens group. Our configuration corrects spherical aberrations and efficiently collects light to achieve diffraction-limited performance across a wide range of wavelengths while simplifying alignment and assembly. Using this approach, we design and construct an example objective lens that features a long front working distance of 61 mm and a clipped NA of 0.30 (limited by an aperture in our experimental setup). We experimentally verify that it achieves monochromatic diffraction-limited resolution at wavelengths from 375 nm to 866 nm without requiring replacement of the lenses or changing the inter-lens spacings, and its performance remains robust across a 46 mm range variation in total length (by adjusting mainly the back working distance). Additionally, we develop a quantitative method to measure the field of view (FOV) using an experimentally calibrated pinhole target. Under 397 nm illumination (i.e., from 40 Ca + ion fluorescence), the objective achieves a resolution of 0.87 μ m with a 540 μ m FOV. This robust, all-COTS, and versatile design is well-suited for a broad range of experiments, supporting high-precision measurements and exploring quantum phenomena.

Purpose: To develop a methodology for development of 3D planning of obese patients larger than CT field of view (FOV) using PHILIPS Pinnacle 3 treatment planning system. Material & Methods: Obese patient larger than CT FOV was scanned on Siemens Emotion Duo CT simulator in two laterally shifted positions. The Patient had appropriate BBs (central and lateral CT markers) on the central plane. The patient was first positioned such that one side of the patient's contour is fully visible in the reconstructed image. Another similar data set was acquired by shifting the patient laterally. A new composite CT data set with a larger FOV was generated by mapping the left and right halves of the two data sets using the indigenously developed software. Typically the images were joined at a user selectable sagittal plane. In this way, it was possible to fuse the above image sets to makeup the full patient for target/structures delineation. A traditional 3D planning on Pinnacle3 was carried out. Results: An acceptable 3D plan data set was generated and dose distribution along with DRR was obtained using Pinnacle3. The DRRs were compared with AP and LAT simulation films and acceptable results were obtained. Similarly, the plan SSDs and depths were compared with data from patient setup with satisfactory results. Conclusion: A methodology has been developed, tested and implemented for the obese patients with larger CT FOV for 3D planning on Pinnacle3. Essentially using this method, the 50 cm diameter FOV limitation of our scanner has been increased to 70 cm FOV. This was useful for a few selected individual cases in our clinic. While the composite data set is dependent upon the accuracy of patient positioning, several improvements are planned for the future.

Medical ultrasound imaging with large field of view (FoV) and high resolution remains a challenge due to the physical limitations of conventional apertures. Coherent multi-transducer ultrasound (CoMTUS) imaging addresses this by coherently combining data from multiple arrays to create a larger effective aperture, improving imaging performance. Accurate calibration of array positions is essential for coherent compounding, requiring sufficient overlap between insonified regions. However, existing CoMTUS implementations using plane waves (PWs) suffer from narrow, depth-dependent overlap of FoV, making calibration challenging and restricting performance. In this work, CoMTUS is extended to diverging wave (DW) imaging to increase FoV and improve calibration robustness. A novel multi-transmission calibration method is proposed to address the reduced coherence of DW echoes. By enabling inter-probe calibration directly from the DW imaging sequence, the proposed framework represents a key step toward future real-time, online CoMTUS calibration. The method was validated through simulations and experiments using two phased arrays imaging tissue-mimicking phantoms and the human abdominal aorta in vivo. Results demonstrate that CoMTUS with DWs enables extended FoV imaging with calibration errors consistently below the diffraction limit, while retaining improved resolution, contrast, and detectability previously demonstrated with PWs. For this two-probe configuration, an optimal divergence angle (β∼60°) and corresponding maximum steering angle (αmax∼32°) were identified, balancing FoV coverage and avoiding direct transmissions between arrays, showing improvements in peak side-to-main lobe ratio up to 4 dB. Increasing the number of DWs improved contrast (gCNR improving from 0.60 to 0.99 in simulations, and 0.50 to 0.65 in vivo), with diminishing returns beyond 11 transmissions. This approach holds potential for advancing ultrasound imaging in clinical applications requiring large coverage and precise anatomical visualization.

Three approaches to selective surface fluorescence detection are described. All three of them depend on the use of extremely high numerical aperture (NA) objectives now commercially available (1.45 NA from Zeiss and Olympus and 1.65 NA from Olympus). The first two approaches are elaborations of "prismless" total internal reflection fluorescence (TIRF), one approach with a laser illumination and the second with arc lamp illumination. The new higher NA objectives are much more suitable for TIRF work on biological cells in culture than are 1.4 NA objectives previously described for prismless TIRF. The third approach is not TIRF at all. It uses the high aperture objective to selectively gather the emission of fluorophores located close enough to the substrate for their near-field energy to be captured by the substrate. Schematic diagrams, experimental demonstrations, and practical suggestions for all these techniques are provided.

Fabrication of microneedles using two photon-polymerization with low numerical aperture

Various attempts have been discussed to overcome the lateral resolution limit and thus to enlarge the fields of application of optical interference microscopy. Microsphere-assisted microscopy and interferometry have proven that the imaging of structures well below Abbe’s resolution limit through near-field assistance is possible if microspheres are placed on the measured surface and utilized as near-field assisting imaging elements. The enhancement of the numerical aperture (NA) by the microspheres as well as photonic nanojets was identified to explain the resolution enhancement, but also whispering gallery modes and evanescent waves are assumed to have an influence. Up to now, to the best of our knowledge, there is no complete understanding of the underlying mechanisms and no model enabling to examine ideal imaging parameters. This contribution is intended to clarify how much the lateral resolution of an already highly resolving Linnik interferometer equipped with 100 × NA 0.9 objective lenses can be further improved by microspheres. Our simulation model developed so far is based on rigorous near-field calculations combined with the diffraction-limited illumination and imaging process in an interference microscope. Here, we extend the model with respect to microsphere-assisted interference microscopy providing a rigorous simulation of the scattered electric field directly above the sphere. Simulation and experimental results will be compared in the three-dimensional spatial frequency domain and discussed in context with ray-tracing computations to achieve an in-depth understanding of the underlying mechanism of resolution enhancement by the microsphere.

Ptychography, a lensless imaging technology with large field of view (FOV), has been extensively developed in the past decades. However, the demanding coherence of the light source restrains its application in the field of ultrafast imaging, as short light pulses have broad spectral bandwidth and thus poor temporal coherence. Here, we demonstrated the implementation of ultrafast imaging with large FOV by monochromatizing the polychromatic ptychographic diffraction patterns. This scheme relaxes the requirement of bandwidth and successfully realizes the millimeter-scale FOV imaging using ultrashort pulses, while maintaining the good spatial resolution of the order of diffraction limit. Due to the use of a precisely sampled spectrum, the illumination information can be accurately captured allowing more reliable imaging process. Experimental results show that satisfactory spatial resolution can still be achieved even for a relative bandwidth up to 20%. Our work demonstrates the potential of ultrafast diffraction imaging with a large FOV.

ObjectivesTo investigate the prevalence of incidental findings and need for further dental treatment and analyse the influence of size of field-of-view (FOV) and age in cone beam computed tomography (CBCT) for pre-implant planning.Methods404 CBCT scans were examined retrospectively for incidental findings and need for further dental treatment. Incidental finding-frequencies and need for further treatment were assessed for different age (< 40 years, 40–60 years, > 60 years) and FOV groups (small, medium, large). Intraexaminer and interexaminer agreements were evaluated.ResultsIn 82% of the scans at least one incidental finding was found, with a total of 766 overall. More incidental findings were found in scans with large FOV (98% vs. 72%, OR = 22.39 large vs. small FOV, p < 0.0001) and in scans of patients > 60 years (OR = 5.37 patient’s age > 60 years vs. < 40 years, p = 0.0003). Further dental treatment due to incidental findings was needed in 31%. Scans with large FOV were more likely to entail further treatment (OR = 3.55 large vs. small FOV, p < 0.0001). Partial edentulism and large FOV were identified as risk factors for further treatment (p = 0.0003 and p < 0.0001). Further referral of the patient based on incidental findings was judged as indicated in 5%. Intra- and inter-examiner agreements were excellent (kappa = 0.944/0.805).ConclusionsA considerable number of incidental findings with need for further dental treatment was found in partially edentulous patients and in patients > 60 years. In pre-implant planning of elderly patients, the selection of large FOV CBCT scans, including dentoalveolar regions not X-rayed recently, help to detect therapeutically relevant incidental findings.

The paper proposed a large field of view (FOV) measurement with calibrating the camera and measuring simultaneously. In the measurement, the whole FOV was divided into several smaller ones with overlapping areas between each other. The overlapping areas should contain at least 4 noncollinear feature points in each for computing external parameters and at least 4 noncollinear control points in one of them to start the calculation. To obtain the measurement of the whole large FOV, 2 images (or more) of each small fields of view needed to be taken from different angles. In the process of calculation, theoretical values of the camera were used as the initial values of the internal parameters and the initial values of external values were obtained from a new solution for P4P problem. So, the internal parameters of the camera, the external parameters for each image, and the 3D coordinates of the feature points in the large field of view could be acquired by adjustment method. In our experiment, the large field of view range was 500mm×500mm, the smaller ones corresponding to each image was 200mm×200mm, and the ultimate measurement accuracy was 12μm.

This paper presents the use of a deformable mirror (DM) configured to rapidly refocus a microscope employing a high numerical aperture (NA) objective lens. An Alpao DM97-15 membrane DM was used to refocus a 40×/0.80 NA water-immersion objective through a defocus range of −50–50 μm at 26.3 sweeps s−1. We achieved imaging with a mean Strehl metric of >0.6 over a field of view in the sample of 200 × 200 μm2 over a defocus range of 77 μm. We describe an optimisation procedure where the mirror is swept continuously in order to avoid known problems of hysteresis associated with the membrane DM employed. This work demonstrates that a DM-based refocusing system could in the future be used in light-sheet fluorescence microscopes to achieve video-rate volumetric imaging.

Based on the diffraction theory, the focusing properties of a radially polarized quadratic Bessel–Gaussian beam (QBG) with on-axis radial phase variance wavefront are investigated theoretically in the focal region of a high numerical aperture (NA) objective lens. The phase wavefront C and pupil beam parameter μ of QBG are the functions of the radial coordinate. The detailed numerical calculation of the focusing property of a QBG beam is presented. The numerical calculation shows that the beam parameter μ and phase parameter C have greater effect on the total electric field intensity distribution. It is observed that under the condition of different μ, evolution principle of focal pattern differs very remarkably on increasing C. Also, some different focal shapes may appear, including rhombic shape, quadrangular shape, two-spherical crust focus shape, two-peak shape, one dark hollow focus, two dark hollow focuses pattern, and triangle dark hollow focus, which find wide optical applications such as optical trapping and nanopatterning.