Bioengineering Aids to Reproductive Medicine
Sujoy K. Guba in Bioengineering in Reproductive Medicine, 2020
A high numerical aperture with concomitant large acceptance angle has certain advantages. At the proximal end of the fiber bundle, light will be collected from a large area and the net light trapped and transmitted will be high. At the output end the light will diverge out at the same angle as the acceptance angle provided that the field is air. If the field is water as happens in cystoscopy and liquid filled uterine cavity the divergence angle is reduced. With a large divergence angle larger area is illuminated and it is convenient in obtaining a panoramic view. But a high numerical aperture is not an unmixed blessing. As seen from Equation 3.14 a high numerical aperture is obtained by selecting high refractive index core material. With such a material the light loss in the blue region of the spectrum rises. So if at the input end a spectrally balanced white light enters the fiber bundle, at the output, the light will have depleted blue components thus affecting color contrast perception. In practice therefore a comparatively lower numerical aperture than what can be realized is adopted. At the input a spectral dominance of blue is maintained. To increase the area of illumination, divergence angle is raised by having a tapered fiber cone coupling between the flexible light cable and the rigid fiber bundle within the endoscope.
Dictionary
Mario P. Iturralde in Dictionary and Handbook of Nuclear Medicine and Clinical Imaging, 1990
Aperture ratio. The ratio of the useful diameter of a lens to its focal length. It is the reciprocal of the f-number. In application to an optical instrument, rather than to a lens, numerical aperture is more commonly used. The aperture ratio is then twice the tangent of the angle whose sine is the numerical aperture.
Clinical and histopathological comparison of microneedling combined with platelets rich plasma versus fractional erbium-doped yttrium aluminum garnet (Er: YAG) laser 2940 nm in treatment of atrophic post traumatic scar: a randomized controlled study
Published in Journal of Dermatological Treatment, 2021
N. F. Agamia, O. Sorror, M. Alrashidy, A. A. Tawfik, A. Badawi
Punch biopsies (3 mm) were obtained from the treatment area of patients, before and 1 month after the last treatment session from all groups. Tissue blocks were fixed in 10% buffered formalin, embedded in paraffin, and sectioned in standard fashion stained using standard hematoxylin and eosin (H&E), Gomori-trichrome for demonstration of collagen bundles and orcein stains for demonstration of elastic fibers. (HT25A; Sigma Aldrich, St. Louis, Missouri), Morphometric analysis was independently evaluated by three blinded dermatopathologists on histological sections photographed and uploaded to the computer. The images were captured using a 10× object with the numerical aperture of a high-resolution digital camera. Images were viewed and recorded using an Olympus microscope – equipped with spot digital camera, using computer program MATLAB software (image J, the MathWorks, Inc., Natick, MA). All histometric evaluations were carried out using computer-based software; the epidermal thickness was measured between the top (from the upper part of the granular cell layer) to the bottom (dermo-epidermal junction) of the rete ridges. Five measurements were calculated for each tissue using a computerized software analyzer. Quantification of the collagen by image analyzer showed that the mean colored percent area for the green color in Gomori-trichrome stained sections representing collagen fibers and mean colored percent area for brick-red color in orcein-stained sections representing elastic fibers were measured before and after treatment. The mean values of color percent areas were based on the mean of the pixel number.
Femtosecond Laser Assisted Cataract Surgery: A Review
Published in Seminars in Ophthalmology, 2021
Kanika Agarwal, Kathryn Hatch
On a molecular level, the FSL creates cavitation bubbles, ultimately leading to photodisruption of tissue. It uses precise near infrared scanning pulse energy, creating plasma within tissue, with treatment starting in the anterior planes of the lens and then progressing posteriorly. The free electrons and ionized molecules from the plasma expand as the plasma cools, creating cavitation bubbles separating the tissue.4 The infrared waves created by the laser are not absorbed by the adjacent cornea or lens, resulting in minimal localized trauma to surrounding tissues. The numerical aperture of the FSL affects the spot size and volume, subsequently treating either corneal or lens tissue. For corneal incisions, a larger numerical aperture is required allowing for precise localization of energy. The opposite, or smaller numerical aperture, is necessary when treating the lens.5
Curcumin-loaded microemulsion: formulation, characterization, and in vitro skin penetration
Published in Drug Development and Industrial Pharmacy, 2023
Irene Carolina Luna-Canales, Norma Laura Delgado-Buenrostro, Yolanda I. Chirino, Guadalupe Nava-Arzaluz, Elizabeth Piñón-Segundo, Graciela Martínez-Cruz, Adriana Ganem-Rondero
In order to determine the penetration pattern of CUR into the skin, Confocal Laser Scanning Microscopy was used. Once the permeation study was completed, the pigskin was recovered, and the excess CUR was removed by rinsing with saline solution. Subsequently, an immunofluorescence treatment was applied, permeabilizing the skin with a 1% TritonTM X-100 solution. The samples were incubated with a mixture of a solution of 10 μg/mL of rhodamine-conjugated phalloidin and a solution 1:1000 of Hoechst in PBS. Next, each skin section was fixed between a slide and a coverslip, placing a drop of PBS:glycerol (1:1) on each sample, keeping them in the dark at 4 °C. The samples were analyzed with a Confocal Laser Scanning Microscope (Leica TCS SP8, Germany), without any type of mechanical sectioning. The CUR was excited at a wavelength of 488 nm using an Argon laser [20]. The samples were analyzed with a numerical aperture of 10×/0.4.
Related Knowledge Centers
- Refractive Index
- Microscopy
- Objective
- Oil Immersion
- Ray
- Pencil
- Snell'S Law
- Angular Aperture
- Paraxial Approximation
- Depth of Field