Optical Engineering

Optical Engineering

  • Gert Cuypers added an answer:
    What is the obstacle for underwater optical wireless communications?

    Water have complicated nature, water acts as a big obstacle in the propagation optical light which ends up with reduction of the optical transmittance in very short ranges which can be in the order of a few tens of meters. on the other hand, we can use the visible band of the electromagnetic spectrum (450nm-550nm), where water is relatively transparent to light and absorption takes its minimum value.

    Gert Cuypers · KU Leuven

    Fish.

    More seriously: There are three significant impediments for optical communication in water:

    1) the absorption in water is completely beyond comparison to optical fiber. I have no figures for the first one, but the last one is about 0.2dB/km. For comparison, in terms of photography, that is one stop per 15 km!

    2) The light in an optical fiber is guided by the fiber and does not stray. In water the light is not contained and the free space loss will add on top of the attenuation.

    3) The detector in an optical fiber is aimed at the fiber itself and doesn't "see" anything else. A detector in water will probably also see other sources of light (e.g. the sun), especially if magical low-loss water is used.

    Also, for those interested, the full text of Shailesh Kumar Jha's contribution, the text by Yahya Baykal and Roger Green can be found here:

    http://www.google.be/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCEQFjAA&url=http%3A%2F%2Fopticwise.uop.gr%2Fuseful%2FSIG%2520UW-OWC%2520Scope.pdf&ei=_RgXVJa3J8j8ywOt1AI&usg=AFQjCNGrFt3er5ZUwNdgbHCry-wUgCGFXg&bvm=bv.75097201,d.bGQ

  • be Ravand asked a question:
    Does anyone know how to do simulation of MLL with optisystem software?

    Doese anyone know how do simulate external cavity mode lock laser (MLL) with optisystem?

    I want simulate a 10 GHz MLL operating at 0.001 W at 1555nm gaussian pulse which is used as a clock pulse .

  • Karnam Raghunath added an answer:
    Can anyone recommend any Photon Discriminator Devices for Photon Counting?

    I am using Photon Counting with Hamamatsu PMT, photon discriminator and ni-DAQ for Laser Scanning Microscopy.

    My previous photon discriminator system were custom-designed and it has begun to go wrong so I should replace it. 

    Actually, recently I found the Photon counting unit of Hamamatsu, but it only supports 1 channel. (Links attatched,C9744) (I need at least 2 channel)

    Can you suggest another company or products that can alternate to C9744? 

    I hope that it can support up to 2 channel, and price is reasonable. 

    Karnam Raghunath · National Atmospheric Research Laboratory

    Stand alone Discriminators from Phillips Scientific are one option. Another option is licel which has an integrated system

  • Marius Loch asked a question:
    How do I prepare the TiO2 interlayer for tandem solar cells?

     What precursor do I use for this layers and how can the high temperature step be avoided?

  • Yariv Shamir added an answer:
    Any people know how to stripe a GTWave fibre ?

    In my fibre laser setup,one broken point was investigate in the fibre, so  I have to recleave the fibre and resplice the fibre. However the first step is sperate this two fibres and then do the left work. Hopefully, some people could give me some suggestions. Thanks a lot !

    Yariv Shamir · Soreq Nuclear Research Center

    Sulpuric acid or HF will do the work, also arc discharge from a splicing machine could help, if you can somehow mound a fiber section and drive it through. Not sure how clean you need it, soince some of these methods can leave microscopic debris...they may be lethal in case high intensity is applied...

  • Alessandro Naddeo added an answer:
    Can Solidworks simulation software be used for structural and thermal analysis of cellular structures such as a honeycomb telescope mirror?

    I would like to know if it is possible to do finite element analysis of a honeycomb mirror with SolidWorks simulation software. Is the software able to recognize the cellular geometry of the structure? If so, how does it compare with ANSYS engineering software?

    Alessandro Naddeo · Università degli Studi di Salerno

    I think solidworks solver does not allow to reach a good results in this kind of simulation.

    As previous I suggest you to use Ansys or other FEM analysis software. If you want to use an integrated CAD-CAE system, I can suggest you to use CATIA PLM solution (By Dassault Systemes, the same software house that produce Solidworks) that has a very good solver for FE Analysis.

  • Lin Sun added an answer:
    What is the basic working principle of hyperlens?

    I am reading the attached paper published in 2006 by Zubin jacob et al. it is creative and impressive. but I have some problems to understand it. 

    Q1: when using the cylindrical wave basis to decompose the scattering, what is the explanation for diffraction limit?

    Q2: for the anisotropy material with epsilon_r negative, why the high angular momentum state could penetrate close to the center? how to get the equation (6) ? is the bessel function still the first kind? 

    many thanks

    Lin Sun · National University of Defense Technology

    Thanks for your detailed information, Alex.  That really helps a lot. You mentioned two methods of generating evanescent waves. One is by total internal reflection , the other is by the scattering of tiny objects. And evanescent waves is quite different from surface plasmon plaritons. In fact, I just regard the two as the same, except that surface plasmon plaritons is induced by metal and evanescent waves is not. I am not sure it is right. Since nearly all use two point sources to verify the power of subwavelength resolution, whether the emitted light from point source is the same with the scattered light from the tiny objects? Thank you. 

  • Mohit Sharma added an answer:
    Which software is most suitable for Photonic Crystal Fiber analysis?
    Dispersion vs wavelength, MD vs lambda.
    Mohit Sharma · Birla Institute of Technology, Mesra

    RSOFT is the best suitable software ..........

    1. User friendly 

    2. Easy to simulate

    3. FDTD Based software

    4. Any parameter can be calculate (Depend which module you are using)

    5. Extra program may attached with the simulation (preferable python written program)

    I hope this information will help you. 

  • Dr. Ghanshyam Singh added an answer:
    How does one integrate Optoelectronic-VLSI systems for modern applications?

    Optoelectronics-VLSI technology is inherently a multi-disciplinary field. The building of systems require the gathering of experts such as optical hardware designers, opto-mechanics engineers, semiconductor (optoelectronic) manufacturers, system architects, computer scientists, VLSI circuit designers in the digital and analogue domains, specialists in hybrid integration, assembly engineers, packaging and testing engineers. Research groups tend consequently to be very large and to have sufficient resources for the fabrication of prototypes.

    Do you know of any software and tools? Do you have any suggestions?

     

    Dr. Ghanshyam Singh · Sharda University

    Thanks Martijn for your valuable suggestions.

  • David John Collins added an answer:
    Can we deposit any type of glass onto a substrate using Thermal Evaporator?

    I am trying to deposit glass onto Si wafer. I tried using the ebeam evaporator but the glass is not melting in the chamber despite all parameters being right, I guess the machine is not working fine.

    So I thought of depositing glass film using thermal evaporator. But I could not find any information about this over the internet. 

    So please throw some light if its possible or physically not possible to deposit glass using a thermal evaporator.

    Thanks!

    Bhavyabhushan Yadav

    David John Collins · Monash University (Australia)

    I deposit SiO2 (in granule form) on silicon and other substrates using thermal (e-beam) evaporation regularly, though this may be more or less doable depending on the equipment you have available.

    While the silicon granules will fuse together, you shouldn't necessarily end up with a melted pool of sio2 in the crucible (don't do this). If it is an option, it is very important to sweep the beam in a circular/spiral pattern at a high rate across the target to avoid pitting/cratering and to help maintain a constant deposition rate - we aim for approximately 0.5-1 angstroms/second.

  • Arun Thirumurugan added an answer:
    Reduced graphene oxide (rGO) electrical conductivity?

    Is it possible to get the electrical conductivity of  105 S/m, in the reduced graphene oxide thin film (non-transparent, chemically reduced) ?.

    Arun Thirumurugan · National Institute of Technology Tiruchirappalli

    It is possible.

    Please check the link and attachment for ref.

    http://www.sciencedirect.com/science/article/pii/S0169433211019064

  • Alan Robinson added an answer:
    Rayleigh scattering
    I'm a bit confused about the meaning of parameters that are used in Rayleigh scattering formula (in Fiber Optics). Can someone please explain in a simple way, what are:
    1. photoelastic coefficient
    2. isothermal compressibility
    3. fictive temperature

    I've already read a lot of explanation about them, but I still don't get the meaning, maybe because the explanation was too difficult to understand..

    Thanks.
    Alan Robinson · 4D Optics

    The photoelastic coefficient describes how a material's refractive index changes when the material is stressed or deformed.  It is used to describe strain-induced birefringence in photoelastic experiments, but in the context of Rayleigh scattering it could be some other combination of components of the strain-optic tensor or stress-optic tensor.

    The isothermal compressibility describes how the volume of a material changes when external pressure is applied.

    The fictive temperature is a measure of how disordered the glass is.

    Your formula probably uses the Boltzmann relation to estimate the strain energy locked into the glass, based on the fictive temperature.  The compressibility and photoelastic coefficients are used to predict fluctuations in refractive index from the strain disorder.

    As Richard points out, glasses are intrinsically disordered.  Rayleigh scattering is caused by fluctuations in refractive index.  Dopants such as Germania increase the amount of scattering, but even pure silica glass shows Rayleigh scattering.  Fibres drawn at low temperature have a lower fictive temperature and smaller refractive index fluctuations.

  • Chen Chen added an answer:
    What are the main challenges of Mode Division Multiplexing in optical communication systems?
    One of the recent researches suggests to use the optical modes to carry different channels (with different content, modulation). What are the limitation of using such multiplexing technique? I would appreciate any related book or papers.
    Chen Chen · Nanyang Technological University

    The limitation of using mode division multiplexing in optical communication systems is mode dispersion.

    There are many related books and papers referring to this problem.

  • How can I simulate the Kerr effect in FDTD?
    I want to simulate the Kerr effect of optic, not electric field. Please guide me in simulating the kerr effect in FDTD for optical ring resonator.
    Özgür Önder Karakılınç · Izmir Institute of Technology

    you can use  MEEP  which is free FDTD program developed by MIT 

    http://ab-initio.mit.edu/wiki/index.php/Meep_Tutorial/Third_harmonic_generation

  • Craig Brideau added an answer:
    What is the working principle of a CO2 laser controller which used a TTL compatible signal and is this type of laser CW or Pulsed?

    This type of controller used PWM for input signal of CO2 laser.

    Craig Brideau · The University of Calgary

    Does the laser go completely to 'zero' when it is 'off'? They might be modulating between standby and run currents, which would keep the tube hot.

  • Tsvetanka Babeva added an answer:
    What is the reason behind the shift in output transmission spectra due to infiltration of analytes in photonic crystal waveguide sensors?
    In photonic crystal waveguide based sensors, with the infiltration of analytes of different refractive indices there is a shift in the wavelength. What is the main reason behind wavelength shift due to change in refractive index with respect to photonic crystal. Could Raman scattering be related to this phenomenon?
    Tsvetanka Babeva · Bulgarian Academy of Sciences
    May be the interaction appears but the change of RI contrast is very weak to be detected, i.e there is no measurable shift of the spectrum. In other words the sensitivity of your sensors is not high enough to detect these objects.
  • Gerro Prinsloo added an answer:
    Can anyone help with calculating the loss in optical efficiency due to wind loading?
    I am using ASAP software for ray tracing. I know only builder work. I don't know how to work in command language. I have made a parabolic trough with receiver tube. But do not have much knowledge of ASAP.
    Gerro Prinsloo · Stellenbosch University
    Also search for this type of simulations:
    http://www.cfdsupport.com/construction-at-wind.html
  • Justo Arines added an answer:
    Does the focal point of an ideal lens vary with different phase fronts from the incident beam?
    The planar phase front and the spherical phase front may change the focal point of an ideal micro-lens ( having min aberration). This fact may be enhanced drastically for an incident distorted wavefront.
    Justo Arines · University of Santiago de Compostela
    You can use just one SLM to built in the Hartmann-Shack wavefront sensor and correct the aberrated wavefront. You can see some of my works as an example of realization.
  • Gleb Shtengel added an answer:
    Can anyone give me an explanation of the parameters Q-factor,Threshold and minBER shown in the BER analyzer of Optisystem?
    BER analyzer parameters meaning.
    Gleb Shtengel · Howard Hughes Medical Institute, Virginia, United States
    Just google "q factor and ber". There are a lot of places with detailed explanations. Here is one of them (white paper by Agilent Technologies called "Q Factor: The Wrong Answer for Service Providers and NEMs"):
    http://cp.literature.agilent.com/litweb/pdf/5988-8925EN.pdf
  • Jun Chen added an answer:
    How do shadowgraphy velocity values and PIV velocity values differ? Which method is better?
    Which method is better for spray characterization of velocity- PIV (particle image velocimetry) or shadowgraphy?
    Jun Chen · Peking University
    People usually do not use the shadowgraph to measure velocity, since it's not a good way to obtain the accurate velocity vectors in the flow field. The spatial resolution is also a limitation for velocity measurement. PIV as a method to capture the instantaneous velocity has been widely applied in measuring the low- and even high-speed field, provided that the following features of the tracing particles fit the need for high speed measurements. So if the condition permits, PIV is a better choice.
  • Yevgeniy Ivanisenko added an answer:
    Can anyone recommend software to measure the MTF of a digital image?
    I am currently testing the image quality performance of an optical system consisting of a telecentric objective lens and a scientific CMOS camera. To measure the image quality I have been taking images of a 1951 USAF resolution test target. I capture images continuously as the camera is subjected to a series of environmental tests including operation in a vacuum. I would be interested to know if anyone can recommend suitable software with which I can analyse my images accurately and reliably to determine any changes in image quality that occur during operation of the camera in a vacuum. An example image is shown in the attachment.

    The lens being tested was discussed in one of my previous questions:

    https://www.researchgate.net/post/Does_anyone_know_if_a_commercial_off_the_shelf_camera_lens_will_work_in_a_vacuum
    Yevgeniy Ivanisenko · Paul Scherrer Institut
    QuickMTF is one of the inexpensive tools you can get. Besides I agree that the best way in fact is to use someone's or write a Matlab/Python/Whatever script for this purpose, because it is not much more than a Fast Fourier Transformation.
  • Amor Gama added an answer:
    Is there an optical simulation software in scientific linuxn?
    For ray trace simulation in concentration systems.
    Amor Gama · Unité de Recherche Appliquée en Energies Renouvelables
    Thank you for answer, I find a software under Linux because it offer an opensource Property.
  • Balamurugan Rajamanickam added an answer:
    What lasers could be used for Holographic interferometry (HI) and for speckle-interferometry (ESPI)?
    For ESPI application should we use the lasers which are suitable for HI or we can take a laser with lower quality requirements?
    Balamurugan Rajamanickam · Kumaraguru College of Technology
    i think He Ne laser is good choice because of it is suitable range for normal size object and cheap especially for speckle studies.
    Diode laser has the airy disc problem for some applications but it is also fair for low accuracy measurement
  • Efrain Mejia-Beltran added an answer:
    Why can't uniform FBG have wideband reflectivity, e.g. more than 10nm?
    What is the limitation?
    Efrain Mejia-Beltran · Centro de Investigaciones en Optica
    Certainly, refractive index contrast is a limitation an hence the only parameter that can be modified is the thickness of the high and low refractive index sections along the fiber. The thickness of those sections gives the wavelength that is reflected; for example a thickness of 532 nm for each section reflects 1064 nm (twice the wavelength) and as more sections are fabricated the reflectance increases. So, in principle a uniform FBG reflects only one wavelength; because the thickness is not perfectly defined as there is not an abrupt change, some wavelengths around 1064 nm are also reflected. One way to make a wide band reflecting FBG is something similar to Daniel Poitras´ suggestions; but instead of using several FBG´s, a "chirped" version is more convenient. It consists of a series if high and low refractive index whose thickness (i.e. the FBG period) is gradually increasing and hence covers a band of wavelengths that are reflected. Regards.
  • Xiao Lin added an answer:
    Is there any free software for FDTD analysis or analyzing interference pattern?
    In order to analyze the interference pattern and FDTD analysis of light through Fresnel Zone Plate or various other diffractive optical elements (DOEs), I need some kind of free optical simulator. Can anyone help me in this regard?
    Xiao Lin · Chinese Academy of Sciences
    Like Jacopo mentioned, Meep is free, but you need Linux.
  • Jeeva Balu asked a question:
    Is it always necessary to position the injector vertically to study the spray characteristics using diagnostics instruments?
    If the orientation of injector is different , why have so many publications used vertical position as standard? If the injector is placed horizontally the dynamics will be different. Very few studies are attempted like this.
    Is it always necessary to study the SMD (Sauter mean diameter) value at the tip of the injector?
  • Mohammad Reza Mokhtari added an answer:
    Any suggestions on simulating a transfer function of optical ring resonator SOI?
    I want to simulate a transfer function of optical ring resonator SOI, but I cant, please help me.
    Mohammad Reza Mokhtari · University of Tabriz
    above chapter suggested by Serge is written by Dominik Rabus , he is a famous researcher in this field ,and adequately answers most of your theoretical problems
    by the way if you are going to simulate it with MATLAB or Rsoft you can share your own initial simulation , then we can give you a hand
  • Niels König added an answer:
    Can anyone help with single mode propagating waveguide for OCT?
    What is the reason that requires waveguide propagating the light used in OCT imaging to be single mode? What are the disadvantages to use multimode waveguide for OCT?
    Niels König · Fraunhofer Institute for Production Technology IPT
    The use of single mode waveguides has two effects: 1. coherence in the time-domain is provided, because only one optical propagation path is allowed in single-mode waveguides, in contrast to multi-mode step index fibers (graded index fibers are an exception!) 2. spatial coherence is provided because of the pinhole effect of the singlemode fiber core, which results in limited speckle-effects on your surface/ in the tissue under investigation.
    Graded-index fibers preserve the coherence in time-domain, so they can be used for short lengths. As OCT is mostly using broadband sources, chromatic dispersion is a limiting factor for graded-index fibers. See my publication "Miniaturization and evaluation of fiber optic probes for low-coherence interferometry" for more details.
  • Suresh Merugu added an answer:
    Where are the wavelengths that are higher than 700nm?
    Colorimeter's wavelength.
    Suresh Merugu · Indian Institute of Technology Roorkee
    Hello Iu Zubhin,
    CIE standard Illumination has decided that Colorimetry has Standard operating Wavelength from Visible to till near IR (i.e., 380nm to 1100nm).

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Optical engineering is the field of study that focuses on applications of optics.

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