Single Slit Experiments (2000x2000 & 1000x1000)
Table of Contents
Welcome to the single slit simulation. Simulations are computed in real time using FDTD solutions to Maxwell's equations. Simulations give actual interactions between light and objects in an interpretable solution. For this simulation, the interaction is between monochromatic light and a single slit aperture similar in size to the wavelength of light. The following is a guide to help set up parameters and properly use the simulation.
This is where the wavelength of light is selected. The wavelength is easily changed by left-clicking on the slider and moving the mouse left and right. The wavelength can also be changed by selecting the text box and typing in the desired wavelength. Each color of electromagnetic spectrum has its own corresponding wavelength. For this simulation, wavelength varies in intervals of 5 nm and ranges between 380 nm and 680 nm inclusive. Input outside of this range will result in the parameters resetting to default values when simulation is run.
This is where the size of the aperture is changed. The aperture size is always relative to the size of the wavelength. The value that is changed is a coefficient, and the λ indicates the size of the wavelength. In the case above, the aperture size is equal to the size of the wavelength. Aperture size varies by intervals of 0.5λ and ranges between 0.5λ and 10λ inclusive. Input outside of this range will result in the parameters resetting to default values when simulation is run.
After setting up the parameters click the Run Test button to start the simulation.
When the Run Test button is pressed, the above picture will change to:
Do not exit out of the browser when this is shown. If the browser is closed during this time, the simulation will crash and become unusable. The simulation will be in progress computing the FDTD solution to Maxwell's equations. The simulation computes 15 frames at 23 femtoseconds (10-15 seconds) per frame. Each frame will take about 30 seconds to load. When loaded, the visualization of the simulation will appear in the browser.
Once all the frames are computed and loaded, the Run Test button will revert back to normal.
The simulation has been computed in real time. To playback the animation, click the Animate button. The Animate button will cause the frames to run through in continuous sequence. When the last frame is done, it will loop back to the first frame. Pressing the Stop button will stop the animation and allow viewing of specific frames.
Left-clicking on the slider and moving the mouse allows selecting specific frames.
The legend is to help decipher what is happening with light that is traveling through. The legend shows the magnitude of the electric field for light. In this case, when the light is a bright pink (right side of the scale) then the electric field is equivalent to coming out of the screen. When the light is white, there is no electric field in that space. When the light is a dark purple the electric field is equivalent to going into the screen.
The simulation field is where the simulation will display what is computed. Light will be seen propagating left to right, interacting with the single slit when the two meet. Along the bottom and the left side are scales for how large the simulation frame is. The single slit structure is sitting in the middle of the frame and will update when the aperture size parameter is changed. When the frames are changed, the simulation field automatically shows the simulation at the time listed under the animation slider.
When the simulation field is left-clicked, a zoomed in version of the frame shown will pop-up.
The picture above has been zoomed in and then cut to 40% of its original size. Some detail has been lost. Higher quality pictures are in the simulation. Zooming in allows for a better understanding of what is happening to the light interacting with the single slit.
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1. Next steps |
To get a further understanding of the simulations, it is suggested to look at activities in the Manipulation of Light in the Nanoworld educational module.