Trouble Understanding Fourier Transform IR Machine: Can Anyone Help?

[physical101]

Homework Statement

Im having a real problem trying to imagine what happens inside the machine can anyone help? I thought that at the interferometer a beam is split into two and then recombined with a path difference to introduce interference. Because the IR source is broadband would all of the waves interfere which each other to produce the beat phenomenon when out of phase and interact constructively when there is no phase difference? What I am trying to ask is that after the beam splitter is there only one resultant wave which reaches the detector? I just don't know how a Fourier transform infra red machine is capabale of detecting all of the IR frequencies simutaneousily? Please help

Homework Equations

The Attempt at a Solution

 

[jbsteele]

Yes, after the beam splitter there is only one resultant wave which reaches the detector. The Fourier transform infrared machine is capable of detecting all of the IR frequencies simultaneously by using an interferometer. The interferometer splits the beam into two parts, then recombines them with a path difference to introduce interference. This interference creates a beat phenomenon when out of phase and interacts constructively when there is no phase difference. The different frequencies then interfere with each other, producing a signal that can be detected and analyzed by the detector.

 

[kerimek]

The Fourier Transform Infrared (FTIR) machine is a complex instrument that operates on the principles of interferometry and mathematical algorithms. It is designed to analyze the infrared absorption spectrum of a sample, which can provide information about its chemical composition and structure.

To understand how the machine works, it is important to first understand the basics of interferometry. As you mentioned, at the interferometer, a beam of infrared light is split into two beams and then recombined. The path difference between the two beams creates interference, which is detected by the detector. This interference pattern contains information about the sample's absorption of infrared light.

The IR source in an FTIR machine is broadband, meaning it emits a range of infrared frequencies. When these frequencies are combined with the sample, some are absorbed while others are transmitted. This creates a unique interference pattern that is specific to the sample's composition. The detector then measures the intensity of the interference at different frequencies, which is then converted into a spectrum by a mathematical process called a Fourier Transform.

So, to answer your question, yes, there is only one resultant wave that reaches the detector after the beam splitter. However, this wave contains information about all the IR frequencies that were present in the beam. The Fourier Transform algorithm is able to separate and analyze each frequency, allowing for the detection of all frequencies simultaneously.

I hope this explanation helps you better understand the operation of a Fourier Transform IR machine. If you have further questions, I suggest consulting with an expert or referring to a textbook on the subject.