Optics : Lens Combinations with laser beam problem

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SUMMARY

The discussion focuses on calculating the focal length of a second positive lens in a laser beam expander system, where the first lens has a focal length of 50.0 mm and the input beam diameter is 1.0 mm, expanding to 8.0 mm after the second lens. The relevant equations include the lens formula 1/f = 1/f1 + 1/f2 and the magnification formula Mt = (yf/yi). The user seeks assistance in determining the focal length of the second lens and the separation between the lenses based on these parameters.

PREREQUISITES
  • Understanding of lens formulas, specifically 1/f = 1/f1 + 1/f2
  • Knowledge of magnification calculations in optics
  • Familiarity with laser beam expansion concepts
  • Basic skills in algebra for solving equations
NEXT STEPS
  • Calculate the focal length of the second lens using the lens formula
  • Determine the separation distance between the two lenses
  • Explore beam expander designs and their applications in optics
  • Review optical systems involving multiple lenses and their configurations
USEFUL FOR

Optics students, optical engineers, and anyone involved in designing laser systems or studying lens combinations for beam expansion.

Blitzy89
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Hello. I've been struggling with this problem for some time, and honestly I do not know how to solve it.

Homework Statement



Two positive lenses are to be used as a laser beam expander. An axial 1.0 mm diameter beam enters the short focal length positive lens, which is followed by a somewhat longer focal length positive lens, from which it emerges with a diameter of 8.0 mm. Given that the first lens has a 50.0 mm focal length, determine the focal length of the second lens and the separation between the lenses

I suppose that yi=1.0mm; yf=8.00mm;f1=50.0mm



Homework Equations


Focal length of system = f
1/f = 1/f1 + 1/f2
Magnification of image Mt=(yf/yi) (per lens)


The Attempt at a Solution



I tried to solve this by combining the two lenses as a system, but I can't find an answer that makes sense.
Any help is greatly appreciated.
Thank you
 
Physics news on Phys.org
Do you understand the system before putting numbers in ?

http://www.edmundoptics.com/technical-support/lasers/beam-expanders/
 
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