train:lectures:telescopeoptics

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision		 Previous revision
train:lectures:telescopeoptics [2024/03/24 12:13] – Roy Proutytrain:lectures:telescopeoptics [2024/03/24 12:54] (current) – Roy Prouty
Line 1: Line 1:
 {{url>https://docs.google.com/presentation/d/e/2PACX-1vRmP6pIwNDxbX5YSV0szjqsvHnA0E9LFaD1gDYr5s1Kh5wz8bS2L82NwJN0TXlfarabYbtMSrjnvyBK/embed?start=false&loop=false&delayms=3000}} {{url>https://docs.google.com/presentation/d/e/2PACX-1vRmP6pIwNDxbX5YSV0szjqsvHnA0E9LFaD1gDYr5s1Kh5wz8bS2L82NwJN0TXlfarabYbtMSrjnvyBK/embed?start=false&loop=false&delayms=3000}}
  
-=====Telescope Optics=====+=====Telescope Optics I =====
 The Primary Optical device is the first lens or mirror that light touches. The diameter of the Primary Optical Device is also (generally) the Aperture Diameter. The light-gathering power of a telescope depends on the area of the aperture, and so this "light-gathering power" goes with the square of the diameter or radius. The Primary Optical device is the first lens or mirror that light touches. The diameter of the Primary Optical Device is also (generally) the Aperture Diameter. The light-gathering power of a telescope depends on the area of the aperture, and so this "light-gathering power" goes with the square of the diameter or radius.
  
Line 64: Line 64:
 ---- ----
  
-=====Detector Basics=====+=====Telescope Optics II=====
  
 ====Point-Spread Function==== ====Point-Spread Function====
Line 85: Line 85:
 This FWHM is what we use to report our effective angular resolution. The FWHM (similar to the standard of deviation, $\sigma$) is measured in pixels in image space, but is most useful to discuss in terms of seconds of arc (''). This FWHM is what we use to report our effective angular resolution. The FWHM (similar to the standard of deviation, $\sigma$) is measured in pixels in image space, but is most useful to discuss in terms of seconds of arc ('').
  
 +Determine the effective angular resolution of the "Original Airy" profile shown below. Assume the ASI 432 is placed on the main scope.\\
  
-====Diffraction Limited====+[{{:train:lectures:20240321_airyseeing.png?800|Single Airy Profile with fit. Sum of many Airy Profiles with fit.}}] 
 +Consider a telescope unencumbered by pesky atmosphere and is therefore observing an Airy Disk when observing a point source. Take the $x$ axis to be the number of pixels relative to the center of the profile and estimate the Angular Resolution.
  
  
-[{{https://www.astronomynotes.com/telescop/twmountn.gif|Better Seeing Geometry}}]\\ 
  
-[{{https://www.astronomynotes.com/telescop/twinkle.gif|Poor Seeing Geometry}}]\\ 
-Consider a telescope unencumbered by pesky atmosphere and is therefore observing an Airy Disk when observing a point source. Take the $x$ axis to be the number of pixels relative to the center of the profile and estimate the Angular Resolution. 
  
  
-Determine the effective angular resolution of the "Original Airy" profile shown below. Assume the ASI 432 is placed on the main scope.\\+====Seeing Limited====
  
-[{{:train:lectures:20240321_airyseeing.png?800|Single Airy Profile with fit. Sum of many Airy Profiles with fit.}}] 
  
 +[{{https://www.astronomynotes.com/telescop/twmountn.gif|Better Seeing Geometry}}]\\
 +
 +[{{https://www.astronomynotes.com/telescop/twinkle.gif|Poor Seeing Geometry}}]\\
  
-====Seeing Limited==== 
 Due to the turbulent and inhomogeneous atmosphere, rays of light have many opportunities to refract upon impinging a volume of atmosphere with differing optical properties (think: index of refraction from Snell's Law). These refraction events have the effect of displacing the center of the Airy Profile. By the Central Limit Theorem, the sum$^1$ of many displaced Airy Profiles approaches a Gaussian Profile. This gives us confidence in our choice of a Gaussian PSF (though there are better-matching PSF models; e.g., Moffat Profile). Due to the turbulent and inhomogeneous atmosphere, rays of light have many opportunities to refract upon impinging a volume of atmosphere with differing optical properties (think: index of refraction from Snell's Law). These refraction events have the effect of displacing the center of the Airy Profile. By the Central Limit Theorem, the sum$^1$ of many displaced Airy Profiles approaches a Gaussian Profile. This gives us confidence in our choice of a Gaussian PSF (though there are better-matching PSF models; e.g., Moffat Profile).
  
-Determine the effective angular resolution of the "Sum of 3000 Disp. Airys" profile shown below. Assume the ASI 432 is placed on the main scope.+Determine the effective angular resolution of the "Sum of 3000 Disp. Airys" profile shown above. Assume the ASI 432 is placed on the main scope.
  
 An optical system whose angular resolution is limited by these repeated refraction events is said to be **Seeing Limited**. An optical system whose angular resolution is limited by these repeated refraction events is said to be **Seeing Limited**.
Line 126: Line 126:
  
 ====CODE==== ====CODE====
-[[https://colab.research.google.com/drive/1SocmlQtnegS2GoyTZN7gaM840_eHzxcI?usp=sharing|Google Colab for Detector Basics I]]+[[https://colab.research.google.com/drive/1SocmlQtnegS2GoyTZN7gaM840_eHzxcI?usp=sharing|Google Colab for Telescope Optics II]]
  
 ---- ----