Forum - Technology Development

Hello, I believe this would be the proper place to post some ideas.

I have noticed that the scope is a bit top heavy, which could induce some torque on the animals (ignoring the torque already added by the cables). The top part of the scope is quipped with a sliding mechanism to adjust the focal plane of observation in the brain. This is very useful since we never know where the cells will be. However, the manual mechanism seems a bit tedius.

So, I was wondering if there would be a way to make the focus automatic, and I had one idea.

1- Use of a liquid lens: these lenses can change their focal plane as a function of the voltage applied. I found this company ( http://www.varioptic.com/products/variable-focus/arctic-316/ ) selling a relatively small lens of about 7.75 mm diameter and 2mm thickness. I am still waiting for a quote. Would this be something worth pursuing? Something along these lines would be of great value, not only would the focusing be much more convenient, but obtaining a 3D video would also look very good.

I just got the quote, if anyone is interested.

Artic Development Kit = $ 675 Artic 316 = $ 49 Artic 316-P = $59 316-AR850 = $49 316-AR850-P = $59

Hi Walter,

A few comments,

1. Take a look at this coax cable. It is only 0.3mm thick and is effectively weightless and would provide near 0 torque to the animal. The cable is pretty delicate so we don't use it unless absolutely necessary but if you are very concerned with torque/weight it would be worth trying in your setup. The electronics that do the serialization on the CMOS PCB add about 0.4 grams to the overall weight (when compared to relying on the LVDS of the sensor) but the trade off of being able to use extremely thin/flexible coax cables is well worth it. In our experience, our mice can easily handle the extra weight and perform much better with these thin cables.
2. The Artic lens is a pretty interesting idea. I would be concerned at its weight though. One thought I had was to incorporate a Squiggle motor for remote/automated focusing. We haven't had issues with focusing manually but I could imaging so cool applications if it could be done remotely.

Hey Daniel,

yes, I just received the cable from mouser and it is truly weightless. it is also pretty sensitive, a little bit of it was already damaged just from the shipping.

I also found this paper on using the electrowetting technique for focusing. They use a fiber optic approach for imaging, but the idea is the same.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4517461/pdf/nihms704787.pdf

I am not sure of the weight of the lens, I may purchase one just to give it a try. I wish manufacturers would list weight in their spreadsheets.

Hi Walter,

This definitely seems doable. Maybe I just missed it in the paper but do you have specs on the range of focal lengths you can achieve with a lens like this?

The manufacturer list that the lens can go from -3 to +13 diopters.

If I have my optics equations right I think 13 diopters is equivalent to a focal length of about 75mm which is very long for our small scopes. Maybe it could work with some additional optics.

Yes, that's what I came out with too. I will have to play with some ray tracing diagrams to see if it could be made to work for the very short length.