Questions related to Optical Physics
Hi. I have a question. Do substances(for example Fe or Benzene ) in trace amounts (for example micrograms per liter) cause light refraction? and if they do, is this refraction large enough to be detected? and also if they do, is this refraction unique for each substance?
I also need to know if we have a solution with different substances, can refraction help us determine what the substances are? can it measure the concentration?
Thanks for your help
I have profiled a collimated pulsed laser beam (5mm) at different pulse energies by delaying the Q-switch and I found the profile to be approximately gaussian. Now I have placed a negative meniscus lens to diverge the beam and I put a surface when the beam spot size is 7 mm. Should the final beam profile (at the spot size = 7 mm) be still gaussian? Or the negative lens will change the gaussian profile? Is there any way to calculate the intensity profile theoretically, without again doing the beam profiling by methods like Razor blade method? Thanks.
The figure attached here shows the electronic band structure of TiO2. Projected onto the band structure the weights of electronic orbitals. Such a representation helps us visualize the orbital content of bands a given energy range. In the figure, pink, blue and green colors are the projection of Oxygen px, py and pz orbitals, respectively, on to the valence bands. Similarly, for conduction band, red, orange and brown colors represent projections (weights) of Titanium 3d-xy, 3d-yz+3d-xz , and 3d-eg orbitals.
Considering the band structure, the optical gap(direct) comes along the Gamma-Z direction in the Irreducible Brillouin zone. Given this information and projected band structure in the Gamma-Z region, how one can deduce the selection rules for optical transitions?
How can one say for which polarization of incident light the first band gap excitation occurs? What happens when other polarization are used? What are the selection rules governing the phenomena?
The energy density was calculated using this formula, Energy Density = E/A (J/cm2). Here E is the input energy measured in millijoules, A is the area of the circular spot.
E values I know from LDT analysis.
A value, How to calculate using the following parameters?
Laser Beam diameter= 8 mm
Focal length = 20 cm
Nd:YAG laser = 1064 nm
Pulse width = 10 ns
I'm looking for the formula of periodic metallic nanoring arrays' resonance position. I've searched for plenty of literature with no results. Does anyone have profound physics background and familiar with this? Thanks so much!
Just curious, can someone please show me how does look like the grating pattern of the "axicon" to generate a lattice light-sheet? A picture or general scheme will be greatly appreciated:)
What is the best way one can measure the refractive index of different concentration for the same solution, i.e. silver nitrate AgNO3 in de-ionised water? Silver nitrate AgNo3 in different concentration, i.e. 100mg/l or 50mg/l.
When an electrode made of semiconductor nanotubes/nanowires etc is illuminated an overshoot or transient maximum in the photocurrent is observed. The photocurrent gradually exponentially decreases from the transient maximum and gets saturated after some time.
However, there are also some cases, where the photocurrent keeps increasing instead of decreasing. Why does this increment happen? What is the proper reason behind this? Please explain with proper references.
Thanks in advance.
What additional information does the phase measurement in a frequency-domain imaging technique provide compared with the continuous wave technique that measures only the amplitude of the diffuse light?
Your input will be helpful for me over this topic.
I am trying to understand if there is really a relation of direct energy gap with thermo-optic coefficient (TOC) and if this physics is true.
If we consider following material example,
SiO2, its direct Eg=11 eV while low TOC = 1e-5 /C
on other hand, Si has direct Eg = 3.7 eV, TOC = 1.8e-4 /C,
will it be physically (i mean in physics) correct to give this argument?
I look forward to your expert input.
In grazing incidence optics, COMA gets eliminated if optics has an even number of reflections and not for an odd number of reflection. I tried with ray tracing simulations from 1-4 reflections. Can anyone help to understand analytically?
I am using a light source (UV) to irradiate my sample (sample diameter = 0.5 cm). It is difficult to measure the surface temperature using infrared thermometer since effective diameter area should be more than 3 cm. If you know how to calculate the surface temperature or any paper describes about it, please let me know.
Thank you very much.
I would like to know the different modes supported in an optical fiber with an hexagonal geometry. Do this excited modes depend on polarisation?
If a non-absorbing film is put on a perfect electric conductor the reflectivity of the system is still unity. In case of real metals, interference effects become obvious through interference fringes in the reflection spectra. Since transmittance is zero in these systems, this means that absorption takes place.
In fact, this is known and these systems have been used for a long time e.g. as as high-temperature solar absorbers.
What I could not find in the corresponding literature is any hint on the microscopic nature of the absorption. It could take place in the metal due to a non-zero skin depth, but normally light cannot couple to bulk plasmons at the surface of a metal as the corresponding dispersion relation does not cross the light line. The excitation of a surface plasmon could be possible, but still light has to be coupled in. Since you also find the effect above for normal incidence it can not be a kind of prism coupling etc. Probably I miss something very basic, but what is it that is excited by this absorption and how is the energy converted to heat?
How do you explain the BeamSplitter-evolution of a coherent state with an unknown polarization state that leads to cloning its unknown polarization state?(see attached image for details)
I want to measure the retardance and diattenuation for a set of retarders and polarizer at visible wavelenghts. I would like to know what are the methods and devices to measure those properties.
I have removed Fresnel lens from rear projection TV but it is plane/smooth/without grooves/without Newton rings. It concentrate the solar radiations to some extent. The Fresnel lens with grooves is more effective to concentrate the solar radiations. I am interested to convert it into grooves. I hope that the audience can help me in this regards.
I generate orthogonal spatial modes like Hermite-Gaussian or Laguerre-gaussian from two different laser sources. Thus coming from incoherent sources will they not be orthogonal? Or in other words does having a phase difference affect the orthogonality of these modes?
if in chromatic confocal sensor, a led with low coherence and a multi-mode fiber are used. I wonder this imaging process should be the which one ? In the monograph about fiber optical confocal scanning microscopy by GuMin, he treat the imaging process as totally coherent imaging when a laser and single-mode fiber is used.
I have an autocorrelation setup, which we observed field correlation with quite high visibility. Then, I insert the BBO crystal which converts 990nm to 475nm. I inserted a aspherical convex lens that focus light onto the BBO crystal and a lens to collimate the light onto a detector. The light that enters BBO come from two arms, one arm has a variable path delay. The power I apply is 5mW, with pico-second duration pulse, 13ns repetition rate. I also put a black cardboard in front of BBO to measure its back reflection, so that I have achieved phase matching condition.
However, nothing is observed so far. The reason why I think this is hard because SHG is not even measurable, and we can't optimise it without observing it at the first place. Can anyone suggest what could go wrong in such a set up? Why is there no SHG?
This is used for image reconstruction. Another thing about the modulation of diffuser either it is phase or amplitude or both?
Wavelength-dependent values for the complex index of refraction of many materials are available in the literature.
However, temperature-dependent values seem to be quite scarce.
Any clues to where I can get spectral temperature-dependent values of the complex index of refraction for water and aluminum?
I'm looking for an optical material (preferably, glass, but would consider organics) that has a reasonably flat transmission spectrum spanning from approximately 400 nm to 2000 nm, and does not transmit above that wavelength.
BK7 (and most other soda-lime optical glasses) transmit up to at least 2.5 microns. Hot / cold mirrors and short-pass interference filters never seem to extend far enough (the closest thing I found was the extended hot mirror from Edmund, with a window from 750 nm to 1750 nm). KG type glasses from Schott are alright on the blue side, but don't transmit far enough (cutting out at about 1000 nm).
Is there a common optical material I'm missing?
What happens when electromagnetic wave (EM) incidents on a metal plate? Does it reflect back? If yes then how to calculate how much (percentage) is reflected back. Kindly suggest any mathematical formula to calculate the reflected to incident wave ratio, when EM-wave travel from dielectric medium and incidents on a metal plane.
Your suggestion(s) will be highly helpful.
I'm working on a pump probe setup with one focusing lens for both beams. So the spot size of the pump and the probe would be the same. I'm looking for a way to reduce the probe spot size. (probably using a second lens for the probe beam). Is there any easier way to reduce the spot size?
The focal length of the lens required to couple light into a common fiber (want same gaussian spot size) at 633nm is larger or smaller than the one required at 980nm?
Dear optics experts,
Recently, my colleague says that the colored band around the objective lens can regard as the location of the back focal plane.
Do you think it is reasonable?
Or, is there another rule of thumb to find the position of back focal plane of objective lens?
Sorry for did not contains full information.
I already know that color means the range of the objective lens' magnification.
As you already know, the objective lens is not a singlet, and back focal plane is sometimes located in the inside of objective lens barrel. that's why I am trying to find the rule of thumb.
I'm taking the ratio of the CBS signal intensity to the diffuse background intensity for my CBS analysis and I find that the ratio (enhancement factor is around 1.4 to 1.6 and not 2 or above). I'm collecting the CBS signal in source polarization direction and the diffuse background with orthogonal polarization. What may be the possible causes for less enhancement factor? Is anything wrong with my analysis procedure?
I have obtained psi and del values for different wavelengths for 3 different angles (VASE data).
How do I calculate refractive index using this data.
During the building up a free space Optical Coherence Tomography system, we normally want to align the beam splitter cube as perpendicular to the incoming light direction as possible, because it will make the alignment of the reflected back easier to align and then easier to couple into fiber of the detection part. However, when this beam splitter cube is very perpendicular to the light, there will be light leaking out through the fourth surface. When you block the trans-through surface and the reflect surface, there is still detectable light on the fourth surface, and this amount of light is causing noticeable noise in the interfere fringes. Is there better method to use during the align of a free space OCT system?
Hi, i'm looking for a tool that will enable my to draw good sketches for my article. Most of the sketches will be optical systems, light rays through lens etc.
Can you please recommend me.
Why does dipole moment of water molecule and polarizing effect produced by hydroxyl (OH) group saturate the polarizability of surrounding atoms in response to a light wave field? So the non linear optical susceptibility is decreased in this case.
I am trying to perform mode analysis of a photonic crystal fiber (PCF) using COMSOL multiphysics, which basically gives the effective indices of the modes as output.
As I get two linearly polarized modes at 90 degrees with each other, is there any way to tell which one is the fast/slow axis mode by just looking at the effective index values ?
Hi! Due to symmetry the piezo-optic tensor is represented as a 36 components matrix. Moreover and depending on the crystal structure most of this components are 0 or symmetric. In the case of the alfa-BBO ( 3m structure) this can be represented as (see image), and for the YAG (m3m), see image.
How can I find this symmetries and values for the piezo-optic tensor for structures as beta-BBO (R3c), or in general other laser crystal structures?
References: J.D.Foster. "Thermal Effects in a Nd:YAG Laser"
Y.Vasylkiv "On determination of sign of the piezo-optic coefficients using torsion method"
A Gaussian beam is guided through a Single mode fiber. But if we propagate a Bessel beam through a Single mode fiber, then will it guide the Bessel beam like Gaussian beam? that means will the Bessel beam show the same guiding property in the conventional single mode fiber like Gaussian beam?
Behind the biological material in interaction of logical material, it assumed that acoustic-optics, biophonon formation etc can be responsible for many mysterious phenomenon by/along human mind & body interaction with environment as well.
Logic based entities have another aspect which get highlight in further deep down insight. That’s Shadow Formation. In previous question it’s tried to figure out that what can be different structural & functional aspect in term of mechanism behind shadow formation. Now its specific focus on expected functional matrix of Light & Shadow with reference to be use in any technology other than usual photography. As an outcome of last question is telling that subatomic particle can form shadow. And from ascent eras the role of shadow formation in Eclipse is also in common observation. However both are different phenomenon. Here the question is that why natural systems at cosmos produce shadow and make its link with biological entities. What’s further in to it?
There are two kind of object,
1. One who emit light and one who don’t emit.
2. Those who don’t emit light either reflect the light, pass it on or absorbed it.
Common observation is that shadow get formed against those objects which reflect light by some outer light source (after crossing the light from object). When some time we can see the shadow of bulb, tube light as well if near to more intensive light source. Sometimes human senses recognize many thing in darkness as shadow as well, still or moving. So such common observation give hint that technology formation regarding shadow sciences can possible. Shadow is much more than we ever think, the light-Shadow Matrix is just one aspect, which might include Energy Control, Light & Darkness intensity Control, Parallel / Mirror Movements etc. Might be shadow also give us the hint of formation of Minimum Possible Compact Structure (MPCS) as well
Here are few more questions with aim to go deep and find some clue for Light & Shadow Matrix
1. What can be different aspects of Light-Shadow Matrix?
2. Shadow formation can only occur in presence of light or other natural entities can form shadow as well?
3. What can be Acoustic-Optics Shadow? Is there are relation of acoustic-optics with shadow, can sound mix with light form shadow?
4. Can shadow move with the same speed as the object move for which shadow is getting form?
5. What can be Mirror-Shadow?
6. Do shadow can have same properties as light have but in opposite/ mirror direction?
7. What is real insight of Subatomic Shadow Matrix & Effects (SSME)?
8. Can a shadow escape from Light Absorbing Objects like Black Holes?
9. How can we take shadow under experiments to go deep inside into different structural and functional aspects with reference to technology making?
10. Any other point you want to add
A further addition that any research which shows that how Brain & Senses process the Shadows ?
Thanks in advance for your helping input.
i want to set up an experiment that can adjust the power of light for example 450W/m2, 600W/m2, 750W/m2 and 900W/m2. The light will focus to the plate by fresnel lens. My lens size is 1m X 1m.
Anybody have experience do the lab test for fresnel lens? Can you share something to set up and run the experiment . In my lab just have solar simulator (Halogen lamp), I can't do the experiment using this solar simulator.
So, i need some idea to set up the fresnel lens experiment in lab environment.
As I am interested in reservoir potential of coal and want to work on coalbed methane. Different technologies and software can be used for it, can you guys upload the list. e.g. the mercury porosimetry, helium porosimetry, mercury intrusion/extrusion curves, etc.
I am looking for high power intracavity optics (lens and polarizer).
Wavelength: 755 nm
Pulse energy density: 1.6 J/cm2
Pulse width: 500 ps
Repetition rate: 100 MHz (during pulse build-up for ~ 2 microseconds)
Since the laser system is q-switched, modelocked and cavity dumped, the damage threshold requirement seems to be significantly higher than general stock optics. I have already damaged stock lenses, and some custom-made brewster thin film polarizer before the laser can reach the target energy.
The beam size has been expanded as much as possible inside the cavity with telescope configuration. Only option seem to be to look for a extremely sturdy optical coating.
Does anybody know any custom coating services that specializes in high damage threshold optics or intracavity optics?
(I've heard that hafnium coating is required for high LIDT but do not know about this in detail...)
I am interested to measure the intensity of light in individual arms of a Cyclic Shearing Interferometer.I am facing an issue in this regard and that is as I am trying to place my CCD in any of the arms it blocks the passage of light which stops the intereference itself on a plane.And that is making the intensity measurement due to individual arms troublesome.
1 how to calculate? Is it the ratio of the amplitude of the reflected wave to the incident wave?
2 use which device to measure it? Is it accurate enough?
3 Is there any simple method to measure the wall reflectance? I just want to be sure that the recommended value of 0.5 for simulation is not far from the fact.
we know a nonlinear molecule has 3N degree of freedoms. 3 are translational, 3 are rotational and 3N-6 are vibrational degree of freedoms. but The molecule has another degree of freedoms to storing energy and it is electronic levels.
why we don't consider this degree of freedom?
I have built time domain models of Ag nano particle and all seems fine when I simulate at SPR maximum wavelength. But when I compare the near field enhancement factor with wavelength domain model, they don't match. Also in the time domain model silver seems to exhibit high near field enhancement values even in the visible region (500-600 nm). Can someone suggest if it is appropriate to compare the results of similar models between time and wavelength domains (theoretically it should be same)?
I need to construct phantoms with defined optical properties and I am using materials/chemical that their optical properties are not available. I need to know their optical properties to find out how much (in terms of amount/concentration) of them need to be mixed to create my desired optical properties within the medium (final form).
Also to make sure about my analyses I am interested to measure optical properties of materials by myself in the lab.
So was wondering what are the methods available to measure these coefficient quick and cheap? I know that there are methods like integrating spheres but I don't have access to such an instrument.
Thank you very much.
How to calculate the beam waist of Gaussian beam from its intensity in a crystal? Is there any direct relationship between the beam waist and intensity of a gaussian beam?
Is it due to fact that light slows down in higher refractive index region. So the material force the light within itself.
Same like a water is flowing in pipe , it flows smoothly but in the case of oil flowing in pipe, it flows slowly.... But in this case instead of refractive index, we have viscosity....
Could you please confirm this please
In the context of a Joint spectral amplitude of an SPDC effect is it possible to model a cw-laser with a dirac delta function?
I am working on a project which contains study of storage of different shapes of pulses in three-level lambda system. How can I solve equations involved in adiabatic approximation ?
I am able to convert wavelength(nm) values to photon energy(eV) but I could not find out how to draw Tauc Plot from these values (i.e., reflectance and photon energy)
I use mie theory for predict light transmission of optical ceramic but when I depict the curve transmittance increases in all lambda while must be decreased in several lambda. I d not know what is wrong in my calculation. please guide me.
I want to use the Channeltron to detect the very weak VUV photons @150-180 nm.
The Channeltron is applied by 1500-2500 V high dc voltage, and connected to a photoncounter. When change the discriminator level of the photoncouner, the dark counts are schmatically shown in the attahced figure. My question is where sould I set the discriminitor level when detecting the VUV, setpoint at A, B or C?
Thank you in advance.
I'm curious about the configuration of the reflected circularly polarised light for a half-wave plate on a mirror.
A half wave plate will flip the handedness of CP light (left -> right, or right -> left). Similarly, upon reflection from a mirror, CP handedness will also flip. So, if we imagine R incidence, if a half wave plate is atop a mirror, will the CP light be flipped at the bottom of the HWP (becomes L), then flipped by mirror (becomes R again), then passes back through the HWP to be flipped again (so finally leaves as L). So R -> L or L-> R for a HWP/mirror configuration?
When I calculate the second-order nonlinear optical susceptibilities by using Method from S. Sharma(DOI: 10.1103/PhysRevB.67.165332), I get d33's shape like the image attached which the absolute value of d33 decrease with increased incident light energy under the resonant frequency. In my experience, I always get second-order susceptibilities shape like images of d11.png and d15.png attached.
My questions are:
1. Is the d33 behavior an abnormal one or normal one or wrong?
2. What is the physical meaning of negative second-order optical susceptibilities? Could you give me a clear and easy physical model of explanation?
Jason Yu from Chinese Academic of Science.
Good morning, I am a graduate student, new in researching the transmission and stability of optical solitons. I've read some articles about it, and a method named 'Vakhitov–Kolokolov criterion' have been metioned many times. I am curious about it, also confused.
Could anyone tell me about Vakhitov–Kolokolov criterion in briefly, or introduce some articals deducing it detailedly to me?
I will be deeply grateful.
Is there any open library of designs for making diagrams of optical setups?
For instance, I've found this:
But it's focused more to gravitational waves type of experiments; for microscopy, it doesn't even have an objective...
Just wondering before embarking into expanding it ;)
I have an argon ion laser (cw) with wavelengths from 457-647 nm. Initially they are all together but I am interested in picking up the 488 nm line and mantein its spot size. I have seen there are many kind of prisms and as I am pretty new in this area I would like if anyone could give me any advice.
Many thanks for your help.
I want to transmit a dual tone or dual wavelength optical signal (i.e. the multiplexed one) through a standard single mode fiber, but when I transmit the signal it gets distorted because of various reasons such as dispersion, phase noise etc. so it would be very much helpful if anyone share experience working in this field. Thanking you,