Fraunhofer diffraction and Fourier Transform

In summary, the conversation discusses a lab experiment where a single slit diffraction pattern was obtained and compared to the result of taking a Discrete Fourier Transform in MATLAB. The slit width was known to be 0.000134 m and the MATLAB code used to plot the power spectrum as a function of spatial frequency is provided. The discussion also touches upon the comparison of the width of the central maximum between the experimental and MATLAB results, and potential modifications to the code for a more accurate comparison.
  • #1
bcjochim07
374
0

Homework Statement


In lab, I obtained a single slit diffraction pattern and recorded an image of it. The slit width is known to be 0.000134 m. We are supposed to compare our experimentally-obtained diffraction pattern to the result of taking a Discrete Fourier Transform of the aperture in MATLAB.


Homework Equations





The Attempt at a Solution



Here is my MATLAB code:

E=[-100000:25:100000];
F=zeros(1,8001);
for n=1:8001;
F(n)=0.000134*(sin(pi*0.000134*E(n)))/(pi*0.000134*E(n));
end;
plot(E,abs(F))

Here, E corresponds to spatial frequency (m^-1). I'm plotting the power spectrum as a function of E. Qualitatively, the MATLAB result looks very similar to the experimental result, as one would expect. But can I compare the width of the central maxima? At first, I thought that maybe taking the reciprocal of the width of the central max. of the MATLAB result would yield the same width as I saw experimentally. But then again, I'm not taking into account the wavelength of the light in the code. How could I modify my code to give an accurate comparison?
 
Physics news on Phys.org
  • #2
I guess I'm technically not taking the Discrete Fourier transform but just plotting what I know the Fourier transform should be based on F.T. pairs.
 
  • #3
Any suggestions?
 

FAQ: Fraunhofer diffraction and Fourier Transform

What is Fraunhofer diffraction?

Fraunhofer diffraction is a type of diffraction that occurs when a coherent light source, such as a laser, passes through a slit or aperture and creates a diffraction pattern on a screen placed far away from the source. This type of diffraction is based on the principle of Huygens-Fresnel diffraction, where each point on the aperture acts as a source of secondary waves that interfere with each other to create the diffraction pattern.

What is the difference between Fraunhofer diffraction and Fresnel diffraction?

The main difference between Fraunhofer diffraction and Fresnel diffraction lies in the placement of the screen relative to the aperture. In Fraunhofer diffraction, the screen is placed far away from the source and the aperture, while in Fresnel diffraction, the screen is placed close to the aperture. This difference results in different diffraction patterns, with Fraunhofer diffraction producing a more simplified and easily calculable pattern.

How is Fourier Transform related to Fraunhofer diffraction?

Fourier Transform is a mathematical tool used to analyze and decompose complex functions into simpler trigonometric functions. In the context of Fraunhofer diffraction, Fourier Transform is used to analyze the diffraction pattern and determine the size and shape of the aperture that created it. It allows for the reconstruction of the aperture's transmission function from the diffraction pattern, providing valuable information about the aperture's properties.

What are some practical applications of Fraunhofer diffraction and Fourier Transform?

Fraunhofer diffraction and Fourier Transform have various applications in the fields of optics, imaging, and signal processing. They are used in the design and analysis of optical systems, such as telescopes and microscopes. They are also used in image processing to enhance and analyze images, and in signal processing to analyze and filter signals in various systems, such as communication and audio systems.

Is Fraunhofer diffraction limited to light waves only?

No, Fraunhofer diffraction can occur with any type of waves, including sound waves and water waves. However, the mathematical analysis of Fraunhofer diffraction is most commonly applied to light waves, as it is easier to measure and manipulate light waves compared to other types of waves.

Similar threads

Back
Top