Explanation for homemade digital microscope's optical systems?

[harundurmush]

TL;DR

I need some resources or explanations for how to create the microscope with raspberry pi camera. The optical system is hard to understand for me.

Some resources mention about eyepiece lenses for human-eye microscopes (not digital ones). Also some sources says that removing the lens from the camera module of raspberry pi and combine it with a objective lens such as TREEYE 15.3 mm is enough to create optical system for microscope. What is the reason and simplest explanation about this?

 

[berkeman]

Welcome to PF.

Can you post links to your reading about this question? That would make it easier for us to try to help.

Also, what microscope specifications are you shooting for? What magnification power, depth of field, object distance, etc?

 

[harundurmush]

Hi, I am adding the link:

https://github.com/IBM/MicroscoPy

 

[Drakkith]

Per the link:

The microscope has a simple operation principle based on changing the magnification and the focus by adjusting the relative distances between a camera, a single objective lens and a sample.

Unfortunately I can't find anything about the objective lens, either in the link itself or the linked youtube video from the page. You might use the lens that was removed from the camera module, but I really don't know.

 

[Tom.G]

I am not familiar with the Pi camera, but here is what I have found to work with some small digital cameras.

The cameras in this post are the ones with a lens that is threaded onto the body, in front of the sensor. They have a set screw to hold the lens in place and usually some very weak glue. Once you find a screwdriver small enough, loosen the set screw and twist the lens to move it further away from the camera body

Originally, the lens is set to focus everything from a few feet to infinity.

Now we get to the math. This is known as the "Lens Equation":
1/f = 1/do + 1/di
f = Focal length of the lens
d0 = distance to the object you are looking at (from the center of the lens)
di = distance of the image (from center of lens to the camera sensor)

To get a larger image, more magnification, increase the distance between the lens and the image sensor, that is (di) in the above equation. Since the focal length of the lens (f) has not changed, the only way to satisfy the above equation is to decrease (d0), the distance between the lens and the object; move the object closer.

Or you could just put a magnifying glass between the camera and the object -- or mount the camera on a microscope in place of your eye.

Please let us know what works for you. We like to learn too!

Cheers,
Tom

p.s. A further explanation can be found at:
https://www.physicsclassroom.com/class/refrn/Lesson-5/The-Mathematics-of-Lenses

p.s. If you are familiar with electrical circuits, the Lens equation is also the equation for two parallel resistors