Turn a smartphone into a microscope for free?

A while back I found a neat idea for turning a smartphone into a microscope. The idea was you 3D-print a clip to house a minute glass bead (around 1-3 mm across). This essentially acts as an objective lens, considerably magnifying the object in front of the lens (supposedly up to 1000-fold, though I remain sceptical).

Problem is... who has glass beads lying around?

As a nice hack, you can get a little way towards recreating the effect with just a drop of water or oil right in front of the lens (best do this on an old phone, people).

1) Kyocera KC01 (budget JP smartphone) with a blob of water over its lens (circled red to give an idea of the extent of the water droplet). The droplet is a little too large and slightly off centre, but illustrates the general idea.

The problem with water is that it evaporates very quickly, and so the magnification strength is lost very quickly. Vegetable oil was much better; I made one application and it lasted for several dozen minutes.

So, demonstration photos:

2) Photograph of thyme leaf broken at the petiole (leaf stem), showing detail of bristles. Taken using a Aquos Crystal with a droplet of vegetable oil approx. 1 mm across. Backlit using a single 100-yen-shop LED light.

 

3) Photograph of thyme leaf, showing detail of spots on the leaf. Taken using a Aquos Crystal with a droplet of vegetable oil approx. 1 mm across. Backlit using a single 100-yen-shop LED light.

For (2) and (3), Much of the blur around the edges is due to the droplet not filling the entire field of view. The clarity isn't exactly great elsewhere, possible because it was a real pain trying to keep my hand still.

The thing I like most about (3) is that I didn't notice those spots until I looked at the magnified image, so even these relatively poor images do help bring your awareness down to the micro level.

4) Photograph of human hair against paper. Taken using a Aquos Crystal with a droplet of vegetable oil approx. 1 mm across.

5) Photograph of Japanese bill at minimum focal distance of Aquos Crystal without modifications. The letters in the white area are around 2 mm across.

6) Photograph of Japanese bill taken using a Aquos Crystal with a droplet of vegetable oil approx. 1 mm across. Backlit using room light (approx. 3000 lux, according to lux meter)

I took (6) to get a rough idea of the magnification. On my computer screen the character extends 7 cm across my display without too much blurring (though, this may be more of a problem of my hand shaking, rather than the optics), which would suggest a magnification of around 70 mm / 2 mm = 35 fold. However, I should also account for the fact the unmodified camera produces characters of about 1 cm across on my screen, which in itself corresponds to a magnification of 10 mm / 2 mm = 5 fold. So in fact, the oil droplet was only 7 times more powerful than the unaided device.

Nonetheless, the patchiness of the printing is a feature that is almost impossible to detect with the naked eye, and yet became very prominent on using the oil droplet.

But, at only ~7 times better than the standard smartphone lens, I guess dishing out for a cheapo magnifying glass would give better results.

Unsurprisingly, seems people have already thought of this approach, here. Seems that by using polymers instead, you can bake them into permanent lenses. Cool!

I'd be thrilled to hear of any improvements to this. My first thought is to attempt producing a bead by melting clear plastic to flow along a wire into some cold water, which should hopefully solidify the bead in a... bead shape. I don't expect it to work, but it would be better than buying a box of 15000 beads and having 14999 spare beads...

Unless I can think of a use for 14999 glass beads...

EDIT: So, some obvious improvements:
1) You can buy a screen protector -they are clear and don't interrupt with the light getting to the lens too much-, which means you can use oil without worrying about damaging the lens.
2) You can apply PVA glue to this screen protector. When it dries, it becomes transparent, and you can indeed get a lensing effect from it! Decidedly more of a permanent solution that water and oil..