FTIR Resolution (cm^-1 To Nm) - Zemax Community

Skip to main content

• Knowledgebase
• Community
  • • Forum overview
    • Recently active topics
    • Unanswered questions
    • General Discussion
    • User News & Alerts59
    • Licensing and Installation181
    • Got a question?3123
    • People & Pointers215
    • Programming OpticStudio
    • Code Exchange93
    • DLLs76
    • ZOS-API382
    • ZPL212
    • Chinese Forums (中文论坛)
    • 用户新闻和注意事项9
    • 授权与安装9
    • 问题讨论159
    • 用户交流与技术分享60
    • Japanese Forums (日本語フォーラム)
    • ユーザーニュースと注意喚起5
    • ライセンスとインストール2
    • 質問コーナー158
    • ユーザー ラウンジ24
• Ansys Zemax Support FAQs
• User Groups

• Create topic
• Login

• Community
• General Discussion
• Got a question?
• FTIR Resolution (cm^-1 to nm)

• designerguy13-photonics
• Visible

HI community!

Actually i was going through the THOR Lab manual for FTIR spectroscopy and got stuck at understanding the  relationship between resolution expressed in wavenumbers (R cm^1-) and in nanometer (R(nm). In the Table-2 (link given below) of that manual, can someone explains the conversion formulae used for calculation ?            

         FTIR document reference

Best answer by Sven.Stöttinger

Hi,

your link does not seem to work properly, it only directs back to this thread. But I might have an idea what your question is leading to.

Generally using wavelength in nm is somewhat impractical if you want to express a Δenergy-value, since the same Δ-wavelength value in nm relates to a different ΔE in dependence if you for example are looking at the same Δnm value at 300 nm or at 800nm. This is why the wavenumber (cm^-1) or eV as Δenergy units are more commonly used in spectroscopy.

Just an example: at 500 nm a Δ50nm difference corresponds to a ΔE of roughly 225 meV or 1818 cm^-1,at 900 nm however the same Δ50nm difference now correpsonds to a ΔE of roughly 72.5 meV or 585 cm^-1. 

Here is a link to a online calculator where you can put in wavelength and wavelength-difference to get the energy value calculated (sorry it is in german, but looking at the units should help :) ):

https://optikexpertisen.de/interaktiv/spektralkonverter

 

Hope this helps,

Sven

 

https://github.com/designerguy13-photonics

• Physical Optics Propagation
• Interferometer

2 people like this

• Like
• Share

• Sven.Stöttinger
• Infrared
• Answer
• Forum|Forum|3 years ago February 24, 2022

Hi,

your link does not seem to work properly, it only directs back to this thread. But I might have an idea what your question is leading to.

Generally using wavelength in nm is somewhat impractical if you want to express a Δenergy-value, since the same Δ-wavelength value in nm relates to a different ΔE in dependence if you for example are looking at the same Δnm value at 300 nm or at 800nm. This is why the wavenumber (cm^-1) or eV as Δenergy units are more commonly used in spectroscopy.

Just an example: at 500 nm a Δ50nm difference corresponds to a ΔE of roughly 225 meV or 1818 cm^-1,at 900 nm however the same Δ50nm difference now correpsonds to a ΔE of roughly 72.5 meV or 585 cm^-1. 

Here is a link to a online calculator where you can put in wavelength and wavelength-difference to get the energy value calculated (sorry it is in german, but looking at the units should help :) ):

https://optikexpertisen.de/interaktiv/spektralkonverter

 

Hope this helps,

Sven

 

1 person likes this

• Like

• designerguy13-photonics
• Author
• Visible
• Forum|Forum|3 years ago February 25, 2022

Thanks @Sven.Stöttinger , it was helpful. Though i had figured this thing, onlyconfusion was regarding resolution in terms of wavenumber (delta_nu_prime) and resolution in terms of wavelength (delta_lambda). 

The following relation along with your explanation well explains this artifact :

delta_lanmbda = (delta_nu_prime / nu_prime) * lambda

So, let’s say for resoluting a wavelength of 200 nm with resolution of 1cm^-1, 

delta_lambda = (200 nm /50000 cm^-1) * 1 cm^-1 = 0.004 nm

https://github.com/designerguy13-photonics

• Like

Powered by GainsightCommunity Posting GuidelinesCookie settingsAccessibility statement

Sign up

Already have an account? Login

Login to the Zemax Community. Login to the Zemax Community.

Enter your E-mail address. We'll send you an e-mail with instructions to reset your password.

Enter your e-mail address Send Back to overview

Scanning file for viruses.

Sorry, we're still checking this file's contents to make sure it's safe to download. Please try again in a few minutes.

OK

This file cannot be downloaded

Sorry, our virus scanner detected that this file isn't safe to download.

OK

• 
• 
• 
• 

Zemax Community

• Manage email notification
• Private Message Inbox
• My Subscriptions
• Posting guidelines

Need more help?

• Ansys Zemax OpticStudio
• Knowledgebase
• Software Downloads
• Ansys Innovation Courses
• Open a Case

To Chinese users:

Do not provide any information or data that is restricted by applicable law, including by the People’s Republic of China’s Cybersecurity and Data Security Laws ( e.g., Important Data, National Core Data, etc.).

不要提供任何受适用法律，包括中华人民共和国的网络安全和数据安全法限制的信息或数据（如重要数据、国家核心数据等）。

Privacy policy License Agreements Terms of use Cookie Policy Zemax Account Licensing Policies