I have two questions:
First, I am doing the printer test. But for the testing of the nut trap can I use a screw other than the hex drive one specified?
Second, I understand it is possible to upgrade the low cost microscope to the high resolution microscope. Is there more to this than printing the high resolution lens parts and getting the necessary lenses?
Thanks,
Ken
Hi @KenF. For the nut trap test it is best to use the type if screw that you will use for the build. You want to get the feel for how tight you need to screw it in order to embed the nut, and how tight is too tight where you damage the plastic or the screw thread. This will feel different for different drives. If you want to use a screw with a different head, you would need to check that the head size is similar to the DIN size of the M3 socket head, but not bigger. You also need to be able to drive at an angle of 15 degrees to fit the optics module.
Changing from the low-cost optics module to high resolution is as you say just printing the other parts and assembling it with the tube lens and the objective.
Thanks.
Another Qusetion: The instructions say the Condenser arm **should be printed in dark, opaque filament.â I have seen pictures of microscopes where this part is printed in light colors. Would yellow be ok? or should I use something darker like medium blue?
We recently changed the recommendation to dark. The photos across the head of the main instructions still very boldly show a white condenser. I have taken new images, but they have not yet made it to a release.
It is not critical, but it is harder to see to align/focus the illuminated spot if there is a lot of light coming out of the side of the condenser module. I use blue or black. White is bad, yellow is probably also not good.
How dark should the blue be?
What I have is called âblueâ, and it is quite light. The purpose is that light from a bright LED should not show through. If you put something printed in white on top of a phone torch LED it will be almost too bright to look at. You want a colour where the LED does not show through, or at least is dim..
Hi again,
Thanks for the help.
I completed the build but there is a problem. The lens sticks out above the stage. Picture attached.
Also, when looking at a sample should the sample and cover glass face the lens or the light source?
Ken Firestone
If the lens is too high like that, you shoild be able to wind it down using the z-axis actuator. The most recent release of the instructions shows how to centre the actuators (step 2 here).
For the low-cost optics, I think the geometry is set so that the lens is level with the stage when the z-actuator is in the central position. You will need to move it down about 1mm in order to focus on the sample on the under side of the slide.
In general the sample and coverslip should be on the same side as the lens, so on the under side of the slide in an inverted microscope like this. This is particularly important for high magnification lenses as the working distance from the lens to the sample is much less than 1mm. With the low cost optics you can get away with a slide either way up, but if you put a sample on top of the slide then the lens will almost touch the under side of the slide.
What optics are you using? Looking at your photograph it does not look like the Pi Camera lens.
Itâs a 40x lens from IORodeo.
Also is there information about adjusting the illumination online?
*The most recent release of the instructions shows how to centre the actuators (step 2 here).
When I was building at this point I could not get the brass nuts to show, I tried to adjust so nothing but the screw was visible in the window.
If the brass nut is firmly embedded it may not show. The important thing is to have the inner and outer slots aligned.
âFirst useâ instructions are not well developed yet. You want to have the illumination spot focused on the sample, and centred in the field of view. When centering (by loosening the screws on the illumination dovetail) it will help to disable the camera calibration (in the settings tab) so that you see the real illumination. As you align and change the illumination focus you will also need to use the auto hain and shutter speed so tgat it is not too dark or too over bright to be able to see what you are doing.
Hi again,
The microscope seems to be working. To test I lowered the optics and was able to view slides. But this is not an ideal solution.
Using the OpenFlexure Connect program to raise the stage takes forever. How much does each unit actually move? And would I be better off removing the motor and raising the stage manually?
Thanks for all the help. Ken
Once you are focused on a slide the change from one slide to another is small. For first focus the motor is quite slow. Moving by hand is quicker, there is a recent thread here with a method to quickly detach the z-motor Autofocus: motor fast detach system . This will make the motor less stable, that should not matter, although it might make autofocus less reliable.
The focal depth of high resolution lenses is very small, so the z-axis needs to have small steps. The motors are about 4000 steps per turn, and there are 4 turns per mm on the z-axis, or about 62nm per step.
Hi William,
Thanks for all the help so far.
The microscope is built and seems to be working. I emailed IoRodeo and they recommended positioning their lens lower on the slot, which I did with some difficulty.
On some of the slides I have been looking at, from a cheap collection of prepared slides, I find the focus is on artifacts above the sample itself. How can I get the focus on the portion of the sample I am interested in?
And perhaps related, does a positive movement on the Z axis move the stage towards or away from the lens?
Happy Holidays!
Ken
Another forum user had issues with some slides that were prepared with a thick coverslip Unable to focus using x60 or x100 lens . That thread explains some tests and what to expect with a 40x lens.
Or do you mean that you are able to move the lens with the / keys to find the focus that you need, but that the autofocus finds a different focus? In that case there are two âgood focusâ positions, and the autofocus is chosing the one that has more sharp detail. As a human, you have extra knowledge about what you want to see that is not available to the microscope.
The direction of the stepper motors is unfortunately not standard. To find out which way yours are moving, set a move of ~4000 steps. This is one turn of the motor, half a turn of the large gear on the actuator. If you observe the large actuator gear from above, then clockwise rotation is pulling the actuator nut up, which moves the objective down.
What would happen if the acromatic lens were mounted upside down (convex side to camera)?
And if I did this how can I remove the lens?
Having the tube lens the wrong way up will mainly affect aberrations in the image - the focus might not be as good, or different parts of the image might focus differently, or different colours might focus differently. There will also be a slight change of the focal position.
It is possible to get the lens out, but it takes a lot of care to avoid damaging it. You need to keep fingers, and anything oily, dusty or hard off the lens. A glasses cloth is soft and lint free. You could carefully push that up the optics module with a wooden stick like the back end of a pencil.
