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Bookmark or Share- optics - Does putting an aperture in a laser beam make the smallest ...If you put an aperture in a laser beam to block some of it, I would imagine that the spot it can be focused to becomes larger due to diffraction. The numerical aperture of the system is limited by that truncation of the beam. For a regular laser focusing without an aperture, the beam diameter determines the numerical aperture, not the lens ...
- What is the amplitude of the electric field in a laser?$\begingroup$ With respect to the final bullet point, we wish we could make laser beams intense enough to rip electron-positron pairs from the vacuum, but sadly we are a long way from that yet. This is known as the Schwinger limit, about 10^18 V/m, or a focused intensity of about 10^24 W/cm^2.
- optics - Physics of Focusing a Laser - Physics Stack ExchangeWe are going to do that now. Suppose the laser pointer beam is nearly collimated: you measure a divergence of 0.3 milliradians, about 0.017 degrees. Then the waist size is. w0 = M2λ πΘ = 1.5 × 671 ×10−9 π × 3 ×10−4 ≈ 1mm. In this case, they probably designed the laser pointer with an aperture radius of 2 or 3 mm.
- optics - How to calculate spot size of a laser focused through a ...I am trying to figure out how to approximate the spot size of a laser beam that is focused using a microscope objective where the size of the laser beam is smaller than the diameter of the objective. I have tried googling and reading various other questions online but still haven't been able to cobble a coherent plan together.
- electromagnetism - Can a magnetic field be focused at a distance ...This is discussed in Can magnetic fields be redirected and focused at one point? and examples are the solenoid, the Halbach array, and an iron cone. However, these all appear to be limited in their range. In contrast, light can be focused at a distant point, for example with a magnifying lens. A laser beam can be focused such that its ...
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