Miniscope Board
General Category => Optics => Topic started by: ramseya on July 25, 2016, 04:37:14 PM
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Dear all,
We are currently trying to get in contact with companies that manufacture GRIN lenses appropriate for the scopes. Can anyone provide information about GRIN lenses they obtained recently (since GrinTech has become less than cooperative), for example which company, the specifications of the lenses, cost, and whether or not they produced quality images? Anything would be a great help. Additionally, we have GRIN lenses for the Doric system. Is the scope able to be modified to accommodate the Doric lenses?
Best,
Austin
Graduate Research Assistant
University of Maryland School of Medicine
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Hi Austin,
We are currently working with GoFoton to develop high quality GRIN imaging lenses and have made great progress. I think they should have a line of GRIN imaging lenses commercially available within the next couple months.
In the mean time, you can purchase 0.25 pitch, 1.8mm diameter GRIN lenses through http://www.edmundoptics.com/optics/optical-lenses/aspheric-lenses/gradient-index-grin-rod-lenses/3145/#f=categories_s|*C11I*,productId_i|3145,27614_s|1.8 (http://www.edmundoptics.com/optics/optical-lenses/aspheric-lenses/gradient-index-grin-rod-lenses/3145/#f=categories_s|*C11I*,productId_i|3145,27614_s|1.8). We have sucessfully used part number #64-519 but likely almost all their their 1.8mm diameter GRIN lenses are compatible with our system. For thinner relay lenses, try and contact Inscopix. Most labs have been unsuccessful requesting price quotes from them but a few labs have managed to get them to supply lenses. I think their new stance is they are willing to supply non-Inscopix labs with lenses at a slight markup over their normal customers.
The Doric system uses GRIN lenses from GoFoton but I do not know enough about the specs of their lenses to be able to tell you if they will work in our system.
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Could you explain what is suboptimal about the Edmunds Optics GRIN lenses? In other words, why do you need to work with GoFoton to make better lenses if the Edmunds already exist and work? Or, what is it that makes some lenses usable and others not? Moreover, what is "wrong" with the GoFoton lenses that are already available? I don't necessarily need to know specifics if that is sensitive information, I am just wondering what kinds of issues one should look out for when using "off-brand" GRIN lenses?
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Most GRIN lenses are designed to collimate fiber optic. As such, they usually have parabolic (2nd order) refraction index profiles, which are ideal for that purpose but are iffy at focusing off-axis light.
GRINtech uses 4th order index of refraction profiles which are much better for imaging.
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All add a few points to Asr's post.
- Edmund Optics lenses are actually rebranded Grintech lenses. They work well but if all you ever want is a 1.8mm diameter lens. We are working with GoFoton to make an assortment of lenses with different diameters and properties to cover all Miniscope applications. Also, there has been a history of Inscopix/Grintech blocking the supply of lenses to Miniscope users so we do not want to be dependent on these rebranded Grintech lenses.
- As Asr said, most commercial GRIN lenses were not designed of short working distance imaging and therefore produce low contrast/high scattered images. You can check out our wiki page discussing this, http://miniscope.org/index.php?title=GRIN_Lens_Information (http://miniscope.org/index.php?title=GRIN_Lens_Information). I will be updating this page with new information on the GoFoton lenses soon.
- Imaging GRIN lenses need to have a gradiant profile that is a bit harder to manufacture than standard collimating GRIN lenses. We also want to have GRIN lenses that are bio-compatible and an NA of at least 0.5.
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I couldn't find Edmund's part #64-519
Does this GRIN lens have similar specs to the ones you guys have tried?
http://www.edmundoptics.com/optics/optical-lenses/aspheric-lenses/gradient-index-grin-rod-lenses/64520/
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Hi Clay,
The #64-519 lens from Edmunds is generally on back order due to many Miniscope labs trying to order it. Look through the other 1.8mm diameter GRIN lenses offered by Edmunds and find one that has a similar overall length to the #64-519.
From my understanding, all these lenses are actually the same basic GRIN lens but cut to different lengths. The Focal Length Specification Wavelength in conjunction with the length of the GRIN lens defines its pitch. The pitch of a GRIN lens governs its optical properties. In other words, just look at the overall length of the lens and find one close to the #64-519 lens. The ideal GRIN lens from Edmunds would actually be a little bit shorter than the #64-519. I suggest trying #64-520 or any lens in between its length and #64-519's length.
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Thanks Dan- have you guys ever tried to get longer lenses and cut/grind your own to size?
I think Ben Grewe said that's what they do in the Schnitzer lab. Maybe we could then just get a big length of the glass together and then just cut off what we need?
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Hi Clay,
From my understanding cutting, polishing, and testing GRIN lenses is a somewhat labor intensive and can be tricky. I think the Schnitzer lab gets all their lenses cut and polished by Grintech but I could be mistaken. Miniscope users are more or less blocked from getting Grintech lenses but I think GoFoton will be able to provide custom cutting services to labs once they commercially release their imaging lenses.