• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 4
  • 3
  • 1
  • Tagged with
  • 9
  • 5
  • 4
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Design And Analysis Of Ultrashort Femtosecond Laser Amplifiers

Ersin, Dogan 01 October 2006 (has links) (PDF)
This thesis presents a compact femtosecond laser amplifier design for optical preamplifiers and power amplifiers consist of theoretical perspective, simulations to analyze and optimize beam performance. The propagation through optical media is simulated for every optical component such as mirrors and nonlinear crystal separately and suggested realignment of these components required increasing amplifier performance. Finally Gaussian beam propagation and aberration compensation has been conducted.
2

Short Wave Infrared Camera Design And Focal Plane Analysis

Bolat Beldek, Tugba 01 February 2012 (has links) (PDF)
The subject of this study is the design of a camera, which has maximum volume of 50 mm x 50 mm x 300 mm, using short infrared wavelength providing Rayleigh criteria. Firstly, the required flux per pixel has been calculated. Throughout these calculations, atmospheric losses have been obtained by MODTRAN program. Also signal to noise ratio has been examined at minimum and maximum integration time intervals. The focal length of the camera has been calculated as it receives 1 m resolution from 8 km distance. Moreover, the lens materials have been used as N-F2, LIF and BaF2 in this six lens system. The design has been done using ZEMAX optical design program and the performance of the system at focal plane was investigated by the help of Seidel aberrations, Modulation transfer Function (MTF), Spot diagram and Optical Path Difference (OPD) fan plot analyses.
3

An engineered design of a diffractive mask for high precision astrometry

Dennison, Kaitlin, Ammons, S. Mark, Garrel, Vincent, Marin, Eduardo, Sivo, Gaetano, Bendek, Eduardo, Guyon, Oliver 27 July 2016 (has links)
AutoCAD, Zemax Optic Studio 15, and Interactive Data Language (IDL) with the Proper Library are used to computationally model and test a diffractive mask (DiM) suitable for use in the Gemini Multi-Conjugate Adaptive Optics System (GeMS) on the Gemini South Telescope. Systematic errors in telescope imagery are produced when the light travels through the adaptive optics system of the telescope. DiM is a transparent, flat optic with a pattern of miniscule dots lithographically applied to it. It is added ahead of the adaptive optics system in the telescope in order to produce diffraction spots that will encode systematic errors in the optics after it. Once these errors are encoded, they can be corrected for. DiM will allow for more accurate measurements in astrometry and thus improve exoplanet detection. The mechanics and physical attributes of the DiM are modeled in AutoCAD. Zemax models the ray propagation of point sources of light through the telescope. IDL and Proper simulate the wavefront and image results of the telescope. Aberrations are added to the Zemax and IDL models to test how the diffraction spots from the DiM change in the final images. Based on the Zemax and IDL results, the diffraction spots are able to encode the systematic aberrations.
4

The Study and Fabrication of High Efficiency Yb:YAG Ring Laser

Cheng, Kuo-Wei 21 July 2005 (has links)
In the past three decades, Nd:YAG has been the dominating high power solid-state laser gain medium. Compared with Nd:YAG, Yb:YAG has lower quantum defects which produces less heat so that it can reduce thermo-optical deformation. In addition, the achieved doping concentration can be 100%, and the absorption FWHM at 941 nm is 18 nm. Based on above listed advantages, Yb:YAG has the potential to replace Nd:YAG. Using Yb:YAG as the laser gain medium in reentrant two-mirror laser cavity, we have succeeded in Yb:YAG ring laser and all the intracavity elements are coated by our electron gun deposition system. The main purpose of my research is to continue the previous result (slope efficiency: 20.1%), and further increasing the slope efficiency of our ring cavity with different round-trip transmittance of couplers. Besides, we measured and analyzed the polarization of the planar and non-planar ring cavities. At present, the highest slope efficiency we achieved is 38.9% with a round-trip transmittance of 16.4%.
5

Optical wireless energy transfer for self-sufficient small cells

Fakidis, Ioannis January 2017 (has links)
Wireless backhaul communication and power transfer can make the deployment of outdoor small cells (SCs) more cost effective; thus, their rapid densification can be enabled. For the first time, solar cells can be leveraged for the two-fold function of energy harvesting (EH) and high speed optical wireless communication. In this thesis, two complementary concepts for power provision to SCs are researched using solar cells – the optical wireless power transfer (OWPT) in the nighttime and solar EH during daytime. A harvested power of 1W is considered to be required for an autonomous SC operation. The conditions of darkness – worst case scenario – are initially selected, because the SC needs to harvest power in the absence of ambient light. The best case scenario of daytime SC EH from sunlight is then explored to determine the required battery size and the additional power from optical sources. As a first approach, an indoor 5m experimental link is created using a white light-emitting diode for OWPT to an amorphous silicon (Si) solar panel. Despite the use of a large mirror for collimation, the harvested power and energy efficiency of the link are measured to be only 18:3mW and 0:1%, respectively. Up to five red laser diodes (LDs) with lenses and crystalline Si (c-Si) cells are used in a follow-up study to increase the link efficiency. A maximum power efficiency of 3:2% is measured for a link comprising two LDs and a mono-c-Si cell, and the efficiency of all of its components is determined. Also, the laser system is shown to achieve an improvement of the energy efficiency by 2:7 times compared with a state-of-the-art inductive power transfer system with dipole coils. Since the harvested power is only 25:7mW, an analytical model for an elliptical Gaussian beam is developed to determine the required number of LDs for harvesting 1W; this shows an estimated number of 61 red LDs with 50mW of output optical power per device. However, a beam enclosure of the developed Class 3B laser system of up to a 3:6m distance is required for eye safety. A simulation study is conducted in Zemax for the design of an outdoor 100m infrared wireless link able to harvest 1W under clear weather conditions. Harvesting 1:2W and meeting eye safety regulations for Class 1 are shown to be feasible by a 1550 nm laser link. The required number of laser power converters is estimated to be 47 with an area of 5 5mm2 per device. Also, the dimensions of the transmitter and receiver are considered to be acceptable for the practical application of SC EH. In the last part of this thesis, two multi-c-Si solar panels are initially used for EH in an outdoor environment during daytime. The power supply of at least 1W is shown to be achievable during hour periods under sunny and cloudy conditions. A maximum average power of 4:1W is measured in the partial presence of clouds using a 10W solar panel. Since the variability of weather conditions induces the harvested power to fluctuate with values of mW, the use of optical sources is required in periods of insufficient solar EH for SCs. Therefore, a hybrid solar/laser based EH design is proposed for a continuous annual SC provision of 1Win ‘darker’ places on earth such as Edinburgh, UK. The 10W multi-c-Si solar panel and the 1550 nm laser link are considered; thus, the feasibility of supplying the SC with at least 1Wper hour monthly using a battery with energy content of only 60Wh is shown through simulations. A maximum monthly average harvested power of 824mW is shown to be required by the 1550 nm laser system that has already been overachieved through simulations in Zemax.
6

Osvětlovací soustava pro konfokální mikroskop s duálním rastrováním / Illuminating system for a tandem-scanning confocal microscope

Slabý, Tomáš January 2008 (has links)
The diploma thesis deals with a design of illuminating system for tandem-scanning confocal microscope using a high-power LEDs.
7

Optický návrh telecentrického f-theta objektivu / Optical design of telecentric F-theta objective

Perháč, Timotej January 2020 (has links)
This thesis deals with optical design of f-theta lens for purposes of precision micromachining using a laser beam. Optical design consists of creating a nominal design according to specifications given by Meopta – optika s.r.o company and a tolerance analysis, which describes manufacturability of given design. Specifications given are most importantly diffraction limited image quality, correction of distortion throughout the field and telecentricity of systém in image space. F-theta lens in this thesis was created using an optical design software called Zemax.
8

Návrh a optimalizace varifokálního objektivu / Design and optimization of varifocal lens

Vilém, Jan January 2015 (has links)
The thesis deals with the design and optimization of varifocal lens for projection illuminating purposes, its mechanical design and manufacturing drawings. It was proceed in the cooperation with Robe Lighting s.r.o., which defined requirement for a new projective objective lens. Lighting fixtures development is a very specific industry with a number of unusual conditions for design and methods of using of the optical systems. In this paper conditions for imaging quality will be defined and a new design of the lens with corrected distortion will be created based on the definition of the conditions.
9

Properties Of High Energy Laser Light Transmission Through Large Core Optical Cables

Kennedy, Christopher 01 January 2013 (has links)
Laser induced damage is of interest in studying the transmission of large amounts of optical energy through step-index, large core multimode fibers. Optical fibers often have to be routed around objects when laser light is being transmitted between two locations which require the fiber to bend into a curve. Depending on how tight the bend is, this can result in transmission losses or even catastrophic damage when the energy density of the laser pulse exceeds the damage threshold of silica glass. The purpose of this study is to: Establish a minimum bend radius that would allow high energy (GW/cm2 ) to be transmitted through multimode fiber. Evaluate unique fiber routing configurations including loops, 180 bends, and S-bends. Develop optical modeling simulations backed with experimental data that can serve to predict critical areas for future systems. Waveguide theory predicts that light traveling through a bend will form whispering-gallery modes that propagate through total internal reflection bounces along the inside of the outer edge of the bend. This is critical since in these locations the energy density of the light will increase significantly, raising the potential of laser damage, nonlinear effects, and transmission losses. This loss is especially problematic when two 90° bends going in opposite directions are in close proximity to each other, forming an ‘S-bend’. Light that is grouped along the outer edge going through the first bend will enter the second bend at a sharper angle which causes much high transmission losses and raises the possibility of failure. iv Models using R-Soft BeamProp and Zemax were developed to study transmission losses, investigate light interactions at critical areas, and predict under which conditions laser damage would occur. BeamProp presents a clearer view of the modal distribution of light within the core of the fiber and is used to analyze how a plane wave with a Gaussian intensity distribution excites the fiber modes. Zemax provides a tool to perform non-sequential ray tracing through the fiber cable and stray light analysis within the core and once the light exits the fiber. Intensity distributions of the cross sectional area of the fiber shows the whispering gallery modes forming as the light propagates around bends and disburses as it propagates afterwards. It was discovered using R-Soft that if the separation distance between bends in an S-bend is approximately 3 mm there exists a condition where maximum transmission occurs. For 365 µm diameter core fiber it was calculated that the difference in output power could be as high as 150%. This was initially completely unexpected; however ray tracing using Zemax was able to verify that this distance allows the light to transition so that it enters the 2nd bend at the optimal angle to enter the whispering gallery mode. Experiments were performed that validated the models’ predictions and images were captured clearly showing the spatial distribution shift of the light within the core of the fiber. Experiments were performed to verify light grouping together to form whispering gallery modes as predicted by Zemax. Microscope images were taken as a function of distance from various bends to observe the periodic nature in which the laser light fills up the fiber. Additionally, a configuration was setup to examine stimulated Brillioun scattering and determine the onset of laser damage in the fiber. Fibers were tested as a function of bend radius and number of shots v and recommendations for future systems were made. Lastly, mechanical failure tests were performed to determine the relationship between stress placed on the fiber through bending and fiber lifetime in a static environment. This allowed a minimum safe bend radius to be calculated for a 30 year lifetime that agreed with previous calculated values.

Page generated in 0.0257 seconds