# Tag Info

1 vote

### Use lens to improve laser engraving speed

To make a spot etch faster, you need a higher power density at the focal spot. There are two ways to get this - get a more powerful laser or make the beam focus to a smaller spot. Two things limit the ...
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1 vote
Accepted

### How does one derive the lens maker's formula for thick lens?

Here is the answer I came up with after thinking about my question again. Consider the derivation of the common lens equation (See below the picture of the linked derivation). Note that one of the ...
• 315
This is essentially conservation of etendue. Etendue ($G$) is the product of area ($A$) and solid angle ($\Omega$): $$G = A\Omega$$ In an optical system etendue can be increased but cannot be ...