Resolving Power - Disadvantages

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In summary: Those are great resources.grating design is a complex subject that must take into account not just the density of 'lines' but also the detailed shape (the 'blaze angle', for example). I recommend starting by reading this:Thanks for the link.grating design is a complex subject that must take into account not just the density of 'lines' but also the detailed shape (the 'blaze angle', for example). I recommend starting by reading this:In summary, grating design can increase resolving power but comes with a few disadvantages.
  • #1
elemis
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So I know resolving power is given by :

Resolvance = λ/Δλ = nN

Where n = order of fringe being observed and N is the no. of slits.

So I was thinking there are a few ways of increasing resolvance :

1.) Decrease the slit width
2.) Increase the order of the fringe we observe.
3.) Increase the number of slits.

However, wouldn't the first option cause a decrease in transmitted light and hence wouldn't our spectra have decreasing intensity ?

Also, for the second option, it is known that intensity of maximas decreases quite quickly from one order to the next... Hence, would our peak have poor intensity as well ?
 
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  • #2
However, wouldn't the first option cause a decrease in transmitted light and hence wouldn't our spectra have decreasing intensity ?
Right. You'll have to find the best slit width, taking both effects into account.
Also, for the second option, it is known that intensity of maximas decreases quite quickly from one order to the next...
Not if the slits are narrow ;).
 
  • #3
increasing the number of slits increases resolution AND intensity
 
  • #4
elemis said:
So I know resolving power is given by :

<snip>

I'm not sure what you are asking about- technologies used for high resolution spectroscopy, grating design, something else...?
 
  • #5
Andy Resnick said:
I'm not sure what you are asking about- technologies used for high resolution spectroscopy, grating design, something else...?

I'm in interested in grating designs that could increase resolving power and the subsequent disadvtages.
 
  • #6
technician said:
increasing the number of slits increases resolution AND intensity

So what changes could I implement that would have some disadvantages ?
 
  • #7
Are you sure you want to get additional disadvantages?
- reduce the number of slits
- use a different width for different slits
- make the slits too small, or too wide
- use the screen too close to the grating, or too far away

If you want to have advantages, avoid all those points.
 
  • #8
mfb said:
Are you sure you want to get additional disadvantages?
- reduce the number of slits
- use a different width for different slits
- make the slits too small, or too wide
- use the screen too close to the grating, or too far away

If you want to have advantages, avoid all those points.

Thanks ! You see what I'm really interested in is the possible trade off's.
 
  • #9
elemis said:
I'm in interested in grating designs that could increase resolving power and the subsequent disadvtages.

Grating design is a complex subject that must take into account not just the density of 'lines' but also the detailed shape (the 'blaze angle', for example). I recommend starting by reading this:

http://gratings.newport.com/library/handbook/handbook.asp

It's the gold-standard reference. Also, I recommend looking at what equipment NIST or other standards labs use to perform precision (say, 1 part in 10^15) spectroscopy.
 

What is the definition of resolving power?

Resolving power is a measure of the ability of an optical instrument to distinguish between two objects that are very close together. It is commonly used in microscopy and astronomy to describe the clarity and sharpness of an image.

What are the disadvantages of low resolving power?

The main disadvantage of low resolving power is that it limits the ability to see fine details and distinguish between closely spaced objects. This can be a significant issue in scientific research where accurate measurements and observations are crucial.

How does the numerical aperture affect resolving power?

Numerical aperture is a measure of the light-gathering ability of an optical system. It is directly related to resolving power, as a higher numerical aperture allows for better resolution and the ability to distinguish finer details.

What are some factors that can affect resolving power?

The resolving power of an optical instrument can be affected by several factors, including the quality of the lenses or mirrors, aberrations in the optical system, and the wavelength of light being used. Environmental conditions such as atmospheric turbulence can also impact resolving power.

Can resolving power be improved?

Resolving power can be improved by using higher quality lenses or mirrors, optimizing the optical system, and using shorter wavelengths of light. However, there is a limit to how much resolving power can be improved based on the physical properties of the instrument and the laws of diffraction.

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