I am working on assembling what I can of my OFM and was working to get the upright illumination put together. I am stuck on the “push fit the lens” step. My lens is not clicking in any way, no matter how much force I provide. I noticed that the image in the instructions (just going off the official V7 build instructions) has a flange around the lens which looks like it goes into the triginal area of the lens holder. My lens does not have a flange. The outer diameter of my lens is 12.86mm and the height is 6.1mm. It is not letting the outer edge interface with the triginal capture device because of the ring inside the lens holder hitting the top of the lens.
The link for the lens that I purchased is (specifically the D13F8H5.8 variant):
So, two questions.
1: Can I use this lens or do I need to get a different one?
2: If I can use this lens, what modifications do I need to do to use it?
The lenses specified do have a flange. For the specified f=5mm this is the most common type. The search given in the page for the lens part Assembly Instructions (openflexure.org) does turn up that type for 5mm focal length. The shortest focal length for a lens of 13mm diameter that does not have a flange, as with yours, is generally the f=8mm that you have found. Searching for 5mm focal length usually turns up the right thing.
You can use the lens that you have, if you are able to edit the OpenSCAD. Your lens will sit further out of the condenser lens clip because it does not go into the hole. The simplest way to get around this is to define the condenser lens as being thicker. It will take a bit of trial and error to get it right.
Alternatively hold it with tape or even adhesive - but not super glue as it can give a white bloom on the lens.
If you are using an objective lens higher than 40x then the longer focal length condenser lens that you have may reduce the resolution that you can achieve because the illumination angle does not fill the NA of the lens. For lower magnification and the low-cost optics it will be fine.
Note: if you are making the upright version using the current release, v7.0.0 Beta1, then there is a bug in the shape of the upright condenser. The fix is in the bug notes on the Openflexure Microscope V7.0.0-beta1 released thread. It is also rectified on the current master build.
Thanks for the feedback. I did read the page before I had placed my order and I have to say that it seemed to be a difficult part to source, even on AliExpress which is where I had ordered it from. There was one entry based on the provided search terms which was selling some for like $25 or something like that. Ridiculous for AliExpress PMMA lenses. All I can guess is that they are taking advantage of the OFM? I also searched on Amazon and had a bit if a hard time finding anything with a short delivery time. (I am looking for shorter delivery times because I am now wanting to get this put together as I have been planning and futzing for over a month now).
I did find the following:
The specs are a bit different, Seems like it has the flange and is the right diameter, but it’s curvature is not the same (its height is only 3.2mm I think). Will this one work better?
As for modifying the existing parts, well, I am trying to do the higher resolution scope and have already received the PLAN objectives and have printed all of the parts to build the modified upright to support the swappable objectives. So, based on your indication that it would be less than ideal, the juice does not seem worth the squeeze to mod the setup to end up in a worse situation.
It is a bit of a pain to find the correct lens, there’s not many suppliers on aliexpress and the search doesn’t work very well because of a bunch of products with lots of options. If it helps this is the one I use in the illumination kits https://www.aliexpress.com/item/1052713746.html?spm=a2g0o.order_list.order_list_main.5.1cee1802eqA5sP
This is so frustrating. Fortunately I have many spare ones I got during the pandemic. The ones I used to buy from Amazon are out of stock and couldn’t find any either.