Easy "Pancake Lenses"

Because paying $2k for a piece of plastic is BS.

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License: CERN Open Hardware Licence Version 2 - Strongly Reciprocal,
also you can use it in a patent but you can't make it as a patent or try to sue others who use a similar system!

While working on the Vector Gear, my upcoming headset (shameless plug), I wanted to use Pancake Lenses. However, all the solutions for it are either not on the market or very expensive. So I decided to open up a phone VR and study it. While doing so and rearranging the optics, I found that setting the lens in a certain way allows it to make clear images when not far from the screen. This allows the display to be extremely compact, while not sacrificing the FOV. This was made to share my findings and find ways to make the lens even less distanced.

Overall, this method turns the distance from the optical lens to the eye much closer than it would otherwise be. To help show this, I used my computer camera (which isn't a super close representation due to the wider FOV and the focusing being slightly off, but is still very close to the distances I deal with when using the display).

To begin, I used the standard checkboard image. This allows me to most clearly check for warping, chromatic abbreviation, etc. The image is below for anyone who wishes to do the same, although perhaps you could use an image with more grids.

Checkerboard Images – Browse 65,982 Stock Photos, Vectors ... 

To see the difference between the current optical unit and the standard, I used the camera to take a picture of how the image looks within the lens, and the distance from the camera to the screen (albeit not to perfect scale of course, not until I print a system for this). Also do be aware that the camera has a low resolution, in reality the brightness of the image seems to almost be completely kept and the images are sharp when you find the perfect depth.

Standard lens view (wider due to angle):

Distance (I'll try to make these better next time, the screen and BG is shown to get a better idea of distance)



Even though the image is not perfect, it's easy to tell that there is a huge difference in distance. In fact, I have reason to believe that changing the lens focus and distance from each other can greatly affect the distance to be reduced even further. I have a prototype of the Vector Gear which uses pancake lenses, and the distances are not greatly off from each other. I believe that further experimentation will help greatly.

However, this does not come without problems. 

As a wise man once said, when God opens a door, he closes a window

In this case, the following occurs:

- Chromatic Abbreviation (Not extreme but noticeable, can be solved with software)

- Made for smaller displays (You would need a larger lens and a more dense lens to have a better image, I can see the pixels on my phone for example, however could be fixed by scaling)

- Wider FOV for smaller area (less of the entire image is shown, which can be seen as both a good and bad thing. It allows the illusion of a much larger display, but you also have to account for the fact that you're working with less screen. A potential fix is again, scaling)

- Warping (Which can be solved with software)

All tests done, including the expansion of the headset's FOV will be recorded and shared for anyone to replicate (Because I HATE gatekeeping), I believe this is well worth the time and effort as it gives what some vendors attempt to sell at a $2k priceline (literal, hello Kopin P95) at what is likely $8 a piece at the very max. I also will be designing the IPD and depth systems to use within the headset, with an electrical based interface (servos and motors instead of regular mechanical).


Version one of the lens holder (check for errors!)

Standard Tesselated Geometry - 68.25 kB - 04/19/2023 at 00:15



Version one of the lens, represented as a 3D model (check for errors!)

Standard Tesselated Geometry - 14.93 kB - 04/19/2023 at 00:15


Vector Gear DXF File For Cutting.dxf

VG Lens 1.0 DXF file for cutting!

AutoCAD DXF - 6.77 kB - 04/19/2023 at 00:07


  • Lens Cut + Files (THE LENS ARRIVED ^^ )

    WalkerDev04/19/2023 at 00:07 0 comments

    The cut design has finally arrived and I have managed to test it with great success!

    Overall, the lens are a success! The FOV vertically is wide to the point where I have to strain my eye to see the top and bottom of the lens! I am working on extending the horizontal FOV as it is comparable to the Quest 2, but WE MUST GO BETTER! In the next cut, I will make the lens bigger!

    Currently, the images are extremely clear and do not require an extremely bright screen! However, there is an obvious chromatic abbreviation and some God Rays, which I can fix with a hot mirror! The entire lens is clear and there is no sweet spot, as the entire lens is completely clear instead of there being a blur effect from what i've seen! It is a little hard to see very small text, but that is probably because i'm testing VIA my phone, where I can see the pixels in some images! Warping also is not very present! 

    I am not sure about the chromatic abbreviation since I used my phone and the proper VR display before, and while the chromatic abbreviation and godrays were present in the phone test, it was not in the display test!

    I use two lens here, a 60mm and 70mm focal length design, both lens being cut from a 70mm diameter! I used the following:

    If you ask them to cut WalkerDev's design, they will know to cut the v1 for now!

    This costed me around $16 to make enough for a headset! That currently is 0.8 percent of the cost I was given when I requested a pancake lens originally! have 4 pairs but have kept the others closed while I work on a cardboard design to test it!

     In the files section of the project, i've attached both an STL and DWG of it for use! You have to play with the distance as i've yet to design the other systems like an IPD adjuster! I also attached a model of a model for a lens holder!

    Feel free to make it, share what you find and more in the Discord Server here!

    In the next update I will upgrade the horizontal FOV and possibly attempt to add a hot mirror to help with the chromatic abbreviation problem! Or maybe test the lens on a proper display and check if the chromatic abbreviation exists then!

    Please adhere to the license guidelines at the bio!

    (I will put the measurements of spacing for the eyes to lens later within the week)

  • Lens Design Completed

    WalkerDev03/03/2023 at 17:00 0 comments

    Small update, the CAD design was completed for the lens and i'm currently waiting for it to be cut, the lens company agreed to send an image of the lens when they are cut! At the time i'm waiting to test out the lens and make the enclosure for it before I share the file completely! However, here is the current 3D representation of the lens, as well as the drawing!

    The lens is designed to give a 40-45 minimum IPD, while having the largest possible FOV! If you look to the left or right, you will see the majority of the screen regardless of your IPD, with the FOV not sacrificing FOV! The lens are made for a 70mm and 60mm lens (given I am remembering correct lol) and will include a LED based diffusion at the peripheral to artificially increase the FOV even further!

    The current cost for the lens should be $20 - $25 so far!

    3D Representation:


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