Fixation Stability with Bessel Beams
Dipesh Bhattarai1, Marwan Suheimat1, Andrew J Lambert2
1School of Optometry and Vision Sciences and Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Kelvin Grove, Queensland, Australia.
Summary
Monitor-based Bessel beams offer superior fixation targets for ophthalmic imaging, improving stability compared to Gaussian beams and traditional bull
Area of Science:
- Ophthalmic imaging
- Optical physics
- Biomedical engineering
Background:
- Stable ocular fixation is crucial for high-resolution ophthalmic imaging instruments.
- Traditional fixation targets may not provide sufficient stability for advanced imaging techniques.
- Bessel beams, with their unique propagation characteristics, are being explored to enhance fixation.
Purpose of the Study:
- To evaluate and compare the fixation stability offered by different types of targets, including monitor-based Bessel beams, laser Bessel beams, and Gaussian beams.
- To determine the efficacy of monitor-based Bessel images as fixation targets for ophthalmic applications.
Main Methods:
- 16 participants fixated on seven different targets (monitor-based and laser-based Gaussian and Bessel beams, plus a bull's eye/cross hair) for 20-second intervals.
- Eye tracking (30 Hz) was used to record eye positions.
- Standard deviations (σx, σy) and bivariate contour ellipse areas (BCEAs) of fixation were calculated and statistically analyzed.
Main Results:
- Significant differences in fixation stability (σy and BCEA) were observed across target types (P < .001).
- Monitor-based Bessel beam targets resulted in significantly smaller vertical eye movements (σy) and fixation areas (BCEAs) compared to bull's eye/cross hair and Gaussian beam targets.
- No significant difference was found for horizontal eye movements (σx) between target types.
Conclusions:
- Monitor-based Bessel beam images provide superior fixation stability compared to conventional bull's eye/cross hair targets and monitor-based Gaussian beams.
- These findings suggest that monitor-based Bessel images are a promising tool for ophthalmic imaging instruments requiring precise and stable ocular fixation.
- Further research is needed to confirm the benefits of laser Bessel beams over laser Gaussian beams for fixation.
Related Concept Videos
01:30Beams
1.9K
Beams are integral components of structural engineering and construction, designed to support loads applied at various points along their length. These long, straight members can be classified based on geometry, cross-section, support type, and equilibrium condition.
Based on geometry, beams can be straight, tapered, or curved. Straight beams are the most common type and have a constant cross-section throughout their length. Tapered beams, on the other hand, have a varying cross-section along...
Based on geometry, beams can be straight, tapered, or curved. Straight beams are the most common type and have a constant cross-section throughout their length. Tapered beams, on the other hand, have a varying cross-section along...
1.9K
03:18Nuclear Stability
23.2K
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together...
To hold positively charged protons together...
23.2K
01:53RNA Stability
35.7K
Intact DNA strands can be found in fossils, while scientists sometimes struggle to keep RNA intact under laboratory conditions. The structural variations between RNA and DNA underlie the differences in their stability and longevity. Because DNA is double-stranded, it is inherently more stable. The single-stranded structure of RNA is less stable but also more flexible and can form weak internal bonds. Additionally, most RNAs in the cell are relatively short, while DNA can be up to 250 million...
35.7K
01:03Fixation and Sectioning
7.9K
Two basic types of preparation are used to visualize specimens with a light microscope: wet mounts and fixed specimens.
The simplest type of preparation is the wet mount, in which the specimen is placed in a drop of liquid on the slide. A liquid specimen can be directly deposited on the slide using a dropper. Solid specimens, such as skin scraping, can be placed on the slide before adding a drop of liquid to prepare the wet mount. Sometimes the liquid is simply water, but stains are often added...
The simplest type of preparation is the wet mount, in which the specimen is placed in a drop of liquid on the slide. A liquid specimen can be directly deposited on the slide using a dropper. Solid specimens, such as skin scraping, can be placed on the slide before adding a drop of liquid to prepare the wet mount. Sometimes the liquid is simply water, but stains are often added...
7.9K
01:19Deflection of a Beam
723
Accurately determining beam deflection and slope under various loading conditions in structural engineering is crucial for ensuring safety and structural integrity. Singularity functions offer a streamlined approach to analyzing beams, especially when multiple loading functions complicate the bending moment equation.
Singularity functions, described in an earlier lesson, are powerful mathematical tools that represent discontinuities within a function commonly encountered in structural loading...
Singularity functions, described in an earlier lesson, are powerful mathematical tools that represent discontinuities within a function commonly encountered in structural loading...
723
01:28Stability
415
The time response of a linear time-invariant (LTI) system can be divided into transient and steady-state responses. The transient response represents the system's initial reaction to a change in input and diminishes to zero over time. In contrast, the steady-state response is the behavior that persists after the transient effects have faded.
The stability of an LTI system is determined by the roots of its characteristic equation, known as poles. A system is stable if it produces a bounded...
The stability of an LTI system is determined by the roots of its characteristic equation, known as poles. A system is stable if it produces a bounded...
415