Effect of Focal Length of Convex Lens on the Intensity of Spot Size of He-Ne Laser

A scanning microscope using a field emission source has been described elsewhere. This microscope has now been improved by replacing the single magnetic lens with a high quality lens of the type described by Ruska. This lens has a focal length of 1 mm and a spherical aberration coefficient of 0.5 mm. The final spot size, and therefore the microscope resolution, is limited by the aberration of this lens to about 6 Å.The lens has been constructed very carefully, maintaining a tolerance of + 1 μ on all critical surfaces. The gun is prealigned on the lens to form a compact unit. The only mechanical adjustments are those which control the specimen and the tip positions. The microscope can be used in two modes. With the lens off and the gun focused on the specimen, the resolution is 250 Å over an undistorted field of view of 2 mm. With the lens on,the resolution is 20 Å or better over a field of view of 40 microns. The magnification can be accurately varied by attenuating the raster current.

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Spot size and effective focal length measurements for a fast axial flow CO2 laser

10.2351/1.5059610 ◽

1997 ◽

Author(s):

Robert J. Steele ◽

Phillip W. Fuerschbach ◽

Danny O. MacCallum

Keyword(s):

Co2 Laser ◽

Focal Length ◽

Axial Flow ◽

Spot Size ◽

Effective Focal Length ◽

Length Measurements

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EFFECT OF THE RUBY LASER MICROBEAM ON MITOCHONDRIA OF KB CELLS SUPRAVITALLY STAINED BY PINACYANOL

The Journal of Cell Biology ◽

10.1083/jcb.41.2.424 ◽

1969 ◽

Vol 41 (2) ◽

pp. 424-430 ◽

Cited By ~ 4

Author(s):

Yasukazu Tanaka

Keyword(s):

Laser Beam ◽

Ruby Laser ◽

Focal Length ◽

Direct Interaction ◽

Experimental System ◽

Spot Size ◽

Kb Cells ◽

Focal Spot Size ◽

Laser Microbeam ◽

Opaque Material

With pinacyanol as the supravital stain, a preferential effect on mitochondria of KB cells was achieved by the irradiation with the ruby laser beam. The observation confirmed the results of other workers using janus green B in the same experimental system. The preferential effect on mitochondria was noted in the area extending 8–10 µ beyond the nonpreferential damage of 4–5 µ in diameter. The opaque material associated with mitochondria possibly represented coagulated protein. The effect involved cristae mitochondriales without severe disarrangement of their structure. The opaque material could be interpreted as the result of direct interaction between mitochondria and the laser beam, even though the mitochondria were noted outside of the previously estimated focal spot size of about 3 µ Within the thickness of 2–4 µ of monolayered cells, larger areas of damage can be accounted for by divergence of the beam which is focused by a microscope objective of very short focal length. A threshold of biologic effectiveness is probably also involved.

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Transparent Object Shape Measurement Based on Deflectometry

Proceedings ◽

10.3390/icem18-05428 ◽

2018 ◽

Vol 2 (8) ◽

pp. 548

Author(s):

Zhichao Hao ◽

Yuankun Liu

Keyword(s):

Data Acquisition ◽

Phase Measurement ◽

Focal Length ◽

Three Dimensional ◽

Normal Direction ◽

Calibration Data ◽

Actual Measurement ◽

Temporal Phase ◽

Convex Lens ◽

Normal Orientation

This paper proposes a method for obtaining surface normal orientation and 3-D shape of plano-convex lens using refraction stereo. We show that two viewpoints are sufficient to solve this problem under the condition that the refractive index of the object is known. What we need to know is that (1) an accurate function that maps each pixel to the refraction point caused by the refraction of the object. (2) light is refracted only once. In the simulation, the actual measurement process is simplified: light is refracted only once; and the accurate one-to-one correspondence between incident ray and refractive ray is realized by known object points. The deformed grating caused by refraction point is also constructed in the process of simulation. A plano-convex lens with a focal length of 242.8571 mm is used for stereo data acquisition, normal direction acquisition, and the judgment of normal direction consistency. Finally, restoring the three-dimensional information of the plano-convex lens by computer simulation. Simulation results suggest that our method is feasibility. In the actual experiment, considering the case of light is refracted more than once, combining the calibration data acquisition based on phase measurement, phase-shifting and temporal phase-unwrapping techniques to complete (1) calibrating the corresponding position relationship between the monitor and the camera (2) matching incident ray and refractive ray.

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Double-Sided Anti-Reflection Nanostructures on Optical Convex Lenses for Imaging Applications

Coatings ◽

10.3390/coatings9060404 ◽

2019 ◽

Vol 9 (6) ◽

pp. 404 ◽

Cited By ~ 5

Author(s):

Hyuk Jae Jang ◽

Yeong Jae Kim ◽

Young Jin Yoo ◽

Gil Ju Lee ◽

Min Seok Kim ◽

...

Keyword(s):

Imaging System ◽

Focal Length ◽

Flat Glass ◽

Optical Transmittance ◽

Spot Size ◽

Fresnel Reflection ◽

Core Element ◽

High Uniformity ◽

Broadband Spectrum ◽

In Series

Anti-reflection coatings (ARCs) from the cornea nipple array of the moth-eye remarkably suppress the Fresnel reflection at the interface in broadband wavelength ranges. ARCs on flat glass have been studied to enhance the optical transmittance. However, little research on the implementation of ARCs on curved optical lenses, which are the core element in imaging devices, has been reported. Here, we report double-sided, bio-inspired ARCs on bi-convex lenses with high uniformity. We theoretically optimize the nanostructure geometry, such as the height, period, and morphology, since an anti-reflection property results from the gradually changed effective refractive index by the geometry of nanostructures. In an experiment, the transmittance of an ARCs lens increases up to 10% for a broadband spectrum without distortion in spot size and focal length. Moreover, we demonstrate ~30% improved transmittance of an imaging system composed of three bi-convex lenses, in series with double-sided ARCs (DARCs).

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Subwavelength Direct Laser Nanopatterning Via Microparticle Arrays for Functionalizing Metallic Surfaces

Journal of Micro and Nano-Manufacturing ◽

10.1115/1.4042964 ◽

2019 ◽

Vol 7 (1) ◽

Cited By ~ 2

Author(s):

Jean-Michel Romano ◽

Rajib Ahmed ◽

Antonio Garcia-Giron ◽

Pavel Penchev ◽

Haider Butt ◽

...

Keyword(s):

Focal Length ◽

Near Field ◽

Cost Effective ◽

Spot Size ◽

Metallic Surface ◽

Metallic Surfaces ◽

Large Area ◽

Transitional State ◽

Direct Laser ◽

Surface Patterns

Functionalized metallic nanofeatures can be selectively fabricated via ultrashort laser processing; however, the cost-effective large-area texturing, intrinsically constrained by the diffraction limit of light, remains a challenging issue. A high-intensity near-field phenomenon that takes place when irradiating microsized spheres, referred to as photonic nanojet (PN), was investigated in the transitional state between geometrical optics and dipole regime to fabricate functionalized metallic subwavelength features. Finite element simulations were performed to predict the PN focal length and beam spot size, and nanofeature formation. A systematic approach was employed to functionalize metallic surface by varying the pulse energy, focal offset, and number of pulses to fabricate controlled array of nanoholes and to study the generation of triangular and rhombic laser-induced periodic surface structures (LIPSS). Finally, large-area texturing was investigated to minimize the dry laser cleaning (DLC) effect and improve homogeneity of PN-assisted texturing. Tailored dimensions and densities of achievable surface patterns could provide hexagonal light scattering and selective optical reflectance for a specific light wavelength. Surfaces exhibited controlled wetting properties with either hydrophilicity or hydrophobicity. No correlation was found between wetting and microbacterial colonization properties of textured metallic surfaces after 4 h incubation of Escherichia coli. However, an unexpected bacterial repellency was observed.

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A practical comparison between the methods of determining the focal length of a convex lens

10.32792/utq/utjsci/vol6/3/9 ◽

2019 ◽

Keyword(s):

Focal Length ◽

Convex Lens

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Determination of Focal Length of a Convex Lens by Autocollimation

Exploring Laser Light ◽

10.1063/9780735420908_024 ◽

1977 ◽

pp. 62-62

Author(s):

T. Kallard

Keyword(s):

Focal Length ◽

Convex Lens

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High efficiency dielectric photonic crystal fiber metalens

Scientific Reports ◽

10.1038/s41598-020-77821-5 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Myunghwan Kim ◽

Soeun Kim

Keyword(s):

Photonic Crystal ◽

Photonic Crystal Fiber ◽

Optical Fibers ◽

High Efficiency ◽

Focal Length ◽

Spot Size ◽

Diffraction Limit ◽

Crystal Fiber ◽

The Core ◽

Light Manipulation

AbstractOptical fibers have been utilized in various fields owing to their superior guiding performance. However, the modification of optical properties and light manipulation in fibers are restricted by the limitation of the core and cladding materials. In addition, the spot size of the light is constrained by the diffraction limit. In this study, we propose an all-dielectric metalens patterned on the facet of a photonic crystal fiber. The metasurface, which contains Si pillars, satisfies the required phase diagram for focusing light with high transmission. The proposed metalens has a focal length of 30 µm and achieves an outstanding efficiency of up to 88% at a wavelength of 1.55 µm, which is approximately 5 times higher than that of a metal-based metalens. We believe that this scheme may pave the way for in-fiber metasurface applications.

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Microsurgery of Sulcus Vergeture with Carbon Dioxide Laser and Injectable Collagen

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348940010900206 ◽

2000 ◽

Vol 109 (2) ◽

pp. 141-148 ◽

Cited By ~ 44

Author(s):

Marc Remacle ◽

Georges Lawson ◽

Jean-Christophe Degols ◽

Isabelle Evrard ◽

Jacques Jamart

Keyword(s):

Carbon Dioxide ◽

Vocal Fold ◽

Carbon Dioxide Laser ◽

Focal Length ◽

Spot Size ◽

Maximum Phonation Time ◽

Pulse Microwave ◽

Vocal Fold Vibration ◽

Vocal Effort

Between January 1989 and June 1998, we operated on 45 patients for sulcus vergeture. The studied population encompassed 38 women (84%) and 7 men (16%). The median age was 36 (range 12 to 71 years). The surgical technique is based on a concept of Cornut and Bouchayer according to which the dissection of the epithelium adherent to the deep subepithelial plane improves the vocal fold vibration. Dissection is performed with a single-pulsed carbon dioxide laser at 2 to 3 W with a pulse duration of 0.1 second. We use the Super-pulse microwave. The Acuspot micromanipulator provides a spot size of 250 μm at 350-mm focal length. When the vocal fold is atrophic, surgery is completed with a bovine or autologous collagen injection; the median injected quantity is 0.3 mL (range 0.1 to 0.4 mL). The epithelial microflap is redraped with fibrin glue. Voice therapy is indispensable for correcting the associated hyperkinetic dysphonia. The median postoperative follow-up period is 5 months (range 1 to 18 months). In terms of median values, the maximum phonation time improved from 9 to 13 seconds, the phonation quotient improved from 296.5 to 228.5 mL/s, and the spectral analysis distribution improved by 1 class. Stroboscopic examination reveals an improvement of the vibratory symmetry, amplitude, and wave. Subjectively, the patients describe an improved ability for vocal effort and the regression or disappearance of vocal fatigue. Although the timbre is improved, the voice often remains breathy and hoarse.

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