Three-dimensional Optical Devices Research Articles

Predicting obstructive sleep apnea hypopnea syndrome using three-dimensional optical devices: A systematic review.

As a global health concern, the diagnosis of obstructive sleep apnea hypopnea syndrome (OSAHS), characterized by partial reductions and complete pauses in ventilation, has garnered significant scientific and public attention. With the advancement of digital technology, the utilization of three-dimensional (3D) optical devices demonstrates unparalleled potential in diagnosing OSAHS. This study aimed to review the current literature to assess the accuracy of 3D optical devices in identifying the prevalence and severity of OSAHS. A systematic literature search was conducted in the Web of Science, Scopus, PubMed/MEDLINE, and Cochrane Library databases for English studies published up to April 2024. Peer-reviewed researches assessing the diagnostic utility of 3D optical devices for OSAHS were included. The Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) guideline was employed to appraise the risk of bias. The search yielded 3216 results, with 10 articles meeting the inclusion criteria for this study. Selected studies utilized structured light scanners, stereophotogrammetry, and red, green, blue-depth (RGB-D) cameras. Stereophotogrammetry-based 3D optical devices exhibited promising potential in OSAHS prediction. The utilization of 3D optical devices holds considerable promise for OSAHS diagnosis, offering potential improvements in accuracy, cost reduction, and time efficiency. However, further clinical data are essential to assist clinicians in the early detection of OSAHS using 3D optical devices.

Crotch detection on 3D optical scans of human subjects

Three-dimensional optical devices are relatively inexpensive and can rapidly acquire body surface scans. Therefore, they can be used as an efficient tool for automatically obtaining landmarks and anthropometric measurements. In this study, we develop an algorithm called DeCIMA (Detecting the Crotch In Mesh Analysis). DeCIMA automatically finds the crotch, as one of the fundamental landmarks on 3D human optical scans. DeCIMA presents a solution for finding the crotch-location even in challenging cases where the subjects’ thighs are connected. We test DeCIMA on 225 scans obtained from 75 human subjects using three different scanners. We compare the crotch height obtained by DeCIMA with the crotch height reported by the proprietary software of the 3D optical scanners. Results show that DeCIMA improves crotch detection and can correctly detect the crotch even for subjects with connected upper thighs.

Self-assembly three-dimensional optical devices: from microsphere to microlens array.

We report rapid formation of three-dimensional micro optical devices by silica nanoparticle self-assembly in a face-centered cubic (fcc) structure. By controlling the hydrophobic interactions, the self-assembled products are fabricated into different morphologies, which include microsphere and hemisphere. These structures have specific applications in microsphere resonant cavities and microlens arrays. The whispering gallery mode of the formed microsphere is excited by the tapered fiber to demonstrate the optical characters of the microsphere. Moreover, the properties of the fabricated microlens and microlens array are tested through insertion in an imaging system. Ultimately, the optical devices with advanced functions are demonstrated by the secondary phase infiltrating into the interstitial space of silica nanoparticles. This report will open a new direction in manufacturing multifunctional and miniature optical devices by an ultrasimple self-assembly approach.

Nonlinear Optical Properties and Femtosecond Laser Micromachining of Special Glasses

Materials specially designed for photonics have been at the vanguard of chemistry, physics and materials science, driven by the development of new technologies. One particular class of materials investigated in this context are glasses, that in principle should exhibit high third order optical nonlinearities and fast response time, whose optical properties can be tailored by compositional changes, such as, for instance, the incorporation of metallic nanoparticles to explore plasmon resonances. Simultaneously to the development of novel materials, and motivated by the need of device miniaturization, direct laser writing by femtosecond pulses has been used to advanced processing of glasses. Such method allows fabricating high resolution three-dimensional optical devices, as well as to produce spatially localized metal nanoparticles. This review paper initially presents results on the nonlinear optical characterization of special glasses, in addition to progresses on the use of femtosecond laser micromachining for producing waveguides and spatially confined metal nanoparticles.

Self-Assembled Quasi-Periodic Voids in Glass Induced by aTightly Focused Femtosecond Laser

Multiple refocusing of a tightly focused femtosecond laser due to thedynamic transformation between self-focusing and self-defocusing isemployed to provide a novel method to produce quasi-periodic voids inglass. It is found that the diameter or the interval of the periodicvoids increases with the increasing pulse energy of the laser. Thedetailed course for producing periodic voids is discussed by analysingthe damaged track induced by the tightly focused femtosecond laserpulses. It is suggested that this periodic structure has potentialapplications in fabrication of three-dimensional optical devices.

Heat accumulation during high repetition rate ultrafast laser interaction: Waveguide writing in borosilicate glass

During high repetition rate (>200 kHz) ultrafast laser waveguide writing, visible heat modified zones surrounding the formed waveguide occur as a result of heat accumulation. The radii of the heat-modified zones increase with the laser net fluence, and were found to correlate with the formation of low-loss and cylindrically symmetric optical waveguides. A numerical thermal model based on the finite difference method is applied here to account for cumulative heating and diffusion effects. The model successfully shows that heat propagation and accumulation accurately predict the radius of the ‘heat modified’ zones observed in borosilicate glass waveguides formed across a wide range of laser exposure conditions. Such modelling promises better control of thermal effects for optimizing the fabrication and performance of three-dimensional optical devices in transparent materials.

Femtosecond Laser Application to PLC Optical Devices and Packaging

Using tightly focused femtosecond laser pulses, we produce an optical waveguide and devices in transparent materials. This technique has the potential to generate not only channel waveguides, but also three-dimensional optical devices. In this paper, an optical splitter and U-grooves, which are used for fiber alignment, are simultaneously fabricated in a fused silica glass using near-IR femtosecond laser pulses. The fiber-aligned optical splitter has a low insertion loss, less than 4 dB, including an intrinsic splitting loss of 3 dB and excess loss due to the passive alignment of a single-mode fiber. Finally, we present an output field pattern, demonstrating that the splitting ratio of the optical splitter becomes approximately 1:1.

Nano-structuring of Transparent Materials by Femtosecond Laser Pulses

Using tightly focused femtosecond laser pulses, we produce an optical waveguide and optical devices in transparent materials. This technique has the potential to generate not only channel waveguides, but also three-dimensional optical devices. In this paper, an optical splitter and U-grooves, which are used for fiber alignment, are simultaneously fabricated in a fused silica glass using near-IR femtosecond laser pulses. The fiber aligned optical splitter has a low insertion loss, less than 4㏈, including an intrinsic splitting loss of 3㏈ and excess loss due to the passive alignment of a single-mode fiber. Finally, we demonstrate the utility of the femtosecond laser writing technique by fabricating gratings at the surface and inside the silica glass.

Fabrication of Three-Dimensional Micro Optical Device

By use of localized modification of transparent materials with femtosecond laser pulses the fabrication of three-dimensional photonic device was become possible. In this paper, we report on the fabrication technique of three-dimensional optical devices. We show that the waveguides and the couplers can be fabricated by use of the filamentation of femtosecond laser pulses. We report on the formation and the movement of submicrometer vacancies, called voids and also the formation of three-dimensional shapes of long holes with microscopic diameters. Finally we show the formation of Bragg gratings in soda-lime glass by two-beam interference.

Parallel efficient three-dimensional beam propagation method using the Du Fort-Frankel Technique

We implement the Du Fort-Frankel modified explicit finite-difference beam propagation method (MEFD) to model three-dimensional optical devices using parallel computers. Accuracy comparisons with other parallel FD-BPMs are made, and we observe that the MEFD is very accurate and efficient. The parallel implementation of MEFD shows a large run-time computer savings compared to other parallel FD-BPM algorithms

Spectral demultiplexer with a plate waveguide

An optical demultiplexer with a fused quartz plate 300 μ thick was developed. Energy from fiber waveguides with a core diameter < 300 μ and an aperture 0.4 was coupled into the demultiplexer without energy losses. The device was capable of demultiplexing five optical carriers in the 0.7–0.9 μ range for a linewidth < 3 nm at spectral intervals of 50 nm. The crosstalk level was less than – 20 dB in respect of the optical power, and the losses in each channel were 3 dB. Promising results were obtained when three-dimensional optical devices were replaced with planar integrated elements based on plate waveguides.