I collect holes in bits of plastic. I have ones varying from about 2mm to 8mm.
I use these for testing my eyes, my pupil size, and optics.
Firstly, where in the U.K. can one buy a set of accurate holes from 1mm or preferably 0.1mm to 8mm?
Today I got a £20 note, which for some reason has ten holes randomly from 0.1mm to 0.3mm. Who put them there I don't know.
An expensive test rig, but I can always spend it.
I noticed recently a probable small cataract in one eye when using sub millimetre holes.
It is tadpole shaped, and from the holes in the banknote it seems to measure 0.05mm across equivalent. It is not central, so I don't notice it when observing and anyway my pupil opens to about 5.5mm.
In the other eye there may be a very small cataract 0.03mm across.
With a 75mm scope, one would need 1,750x and 2,500x for these size exit pupils.
I don't know what size cataracts an optician considers relevant.
And these may not be cataracts, but they appear as tiny black spots with very small holes.
I use these for testing my eyes, my pupil size, and optics.
Firstly, where in the U.K. can one buy a set of accurate holes from 1mm or preferably 0.1mm to 8mm?
Today I got a £20 note, which for some reason has ten holes randomly from 0.1mm to 0.3mm. Who put them there I don't know.
An expensive test rig, but I can always spend it.
I noticed recently a probable small cataract in one eye when using sub millimetre holes.
It is tadpole shaped, and from the holes in the banknote it seems to measure 0.05mm across equivalent. It is not central, so I don't notice it when observing and anyway my pupil opens to about 5.5mm.
In the other eye there may be a very small cataract 0.03mm across.
With a 75mm scope, one would need 1,750x and 2,500x for these size exit pupils.
I don't know what size cataracts an optician considers relevant.
And these may not be cataracts, but they appear as tiny black spots with very small holes.