Difference between revisions of "Cheap Educational Scope"
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*Focal Length of the Eyeball: 2.2cm | *Focal Length of the Eyeball: 2.2cm | ||
− | + | '''Reminder to myself to scan and stick in the raytrace model''' | |
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+ | ==The Cameras== | ||
+ | Walmart! Full lens diameter not usable, need to stop down with a 3mm stop | ||
==The 2-lens Matlab Model== | ==The 2-lens Matlab Model== |
Revision as of 14:07, 12 June 2013
Problem Statement
I needed a quick idea for summer camp educational workshop that was 'sciencey'. I remembered seeing this thingiverse link a while back and sharing it with a friend of mine who is an elementary school teacher. I wanted to do this as a workshop but also to understand the operation behind it as I am ashamed to say that my knowledge of optics is pretty bad...
I also wanted to understand the weak spots of the scope so that older kids could make a more advanced version that would be more capable or easier to use.
The Eye
I first used ray tracing theory to understand the real and virtual image locations. I was hung up very quickly on the fact that without an eye, a virtual image is pretty useless. The eye is an integral part of a microscope!!!
Luckily I found some information on the human eye. Some of the really important ones are
- Visual acuity: 2 arcminutes
- Distance of Nearest Distinct Vision: 25cm (between this and infinity are good places to place your final virtual image)
- Translated visual acuity at the distance of nearest distinct vision: 145µm (wow, my eyes are amazing!!)
- Focal Length of the Eyeball: 2.2cm
Reminder to myself to scan and stick in the raytrace model
The Cameras
Walmart! Full lens diameter not usable, need to stop down with a 3mm stop
The 2-lens Matlab Model
clear; %all units are in meters Fo=.032; Fe=.032; Dndv = .25;%.25 is the distance of "nearest distinct vision" in humans Me = Dndv/Fe; Di = 3.2*Fo; %random guess of 4 Lt=Di+Fe; %tube is the image distance plus the focal length of the occular %M=f/(f-Do) for distance to the object %M = -Di/Do %M = (f-Di)/f for distance to the image Mo = (Fo-Di)/Fo; Do = -Di/Mo; Pe = .003; %entrance pupil of 3mm Theta = atand((0.5*Pe) / Do); NA = sind(Theta); Resolution = (530e-9)/(2*NA); %green light resolution %human visual foveal acuity is 2 arcminutes Aacuitydegrees = 2/60; Dsep = 2*sind(Aacuitydegrees/2)*Dndv; %lowest resolveable distance at Dndv Moptimal = (2*NA*Dsep)/(550e-9) %550nm is green light Mt = Mo*Me
RESULTS ----------------------------- Do = 46.5mm (object-lens distance for an in focus image) Lt = 134.4mm (optical tube length) Moptimal = 17.0354 Mt = -17.1875
2013 Jasper Nance KE7PHI