Let me give you a quick reply now and I'll elaborate more later on.
First, the 51mm glass is type Boro-float. Currently I'm using 1mm thick discs. Flatness is in the range +/- 2 wavelengths (@600nm). Surface quality is 80/50. Next, the 62mm disc is also Boro-float. These are 2mm thick. Flatness is also +/- 2 wavelengths and the surface is 80/50. And the 100mm x 4.5mm glass discs are made from the same materials as the 51 and 62. I chose these because they are high quality but affordable. Edges are not polished, but they are beveled for a better seal. Interesting fact: Once the sealant has cured, the rough edges of the glass become smooth and clear- good for edge lighting.
The 100mm x 12mm glass is BK7. This Crown glass is a harder material at 60/40 surface quality and is flat +/- 1/4 wavelength. These higher quality units have a wider frequency response than Boro-float and their thickness give a greater depth to the 3-d image. Their flatness allow for a thinner mix of fluid between the discs, which increase high frequency response (blue-violet). The only drawback is cost: they are about 3X more $$$ than Boro-float. I have difficulty finding this product in the USA (I think I've bought all of the inventory) and have tried using Chinese made units but do not approve of their quality. Currently I waiting for a new batch to arrive from a US manufacturer. The new batch will have polished and beveled edges.
Thanks for all the info. I find what you are doing to be very interesting. The reason I asked about the glass specs is because I work for an optics manufacturer. I work mostly with Sapphire but I do glass from time to time.
Would you be interested in trying some sapphire windows at no charge no strings attached. The parts below are rejects from our production. They are typically rejected for minor chips around the edge, the customer we make these for uses them as an exit window for a high power laser and won't use them if they are not perfect. I could send you 4-6 of each size if you are interested.
Item #1 Material Optical grade C-plane Sapphire Diameter 60mm +0.00 -0.10mm Thickness 5mm +/-0.10mm Edge bevel 0.30mm +/-0.10mm Polished Parallelism 5 arc seconds max Surface finish 20/10 or better Surface flatness 1/10 - 1/4 wave 90% CA
Item #2 Material Optical grade C-plane Sapphire Diameter 50mm +0.00 -0.10mm Thickness 3mm +/-0.10mm Edge bevel 0.30mm +/-0.10mm Polished Parallelism 5 arc seconds max Surface finish 20/10 or better Surface flatness 1/10 - 1/4 wave 90% CA
I just wanted to make sure you received the parts and they are in good condition. Also do you have an ideal thickness to diameter ratio? For example what thickness would be ideal for the 60mm diameter?
Yes, received them yesterday. Very nice- thank you.
My standard thickness formula will change with the sapphire glass. It isn't as flexible as BK7 or Crown and can be thinner than they are. Basically, each 60mm disc should be 2mm thick. The samples you sent me are twice as thick so these should make a very stable, evenly distributed cell with extended high frequency (blue, violet, UV) response.
I can't wait to try them out. I'll build some cells after the holiday rush (I'm extremely busy now) and post some pix.
Yes, when I get a break from my current workload. I made EMD68 a cell using his sapphire disks and sent it to him in 2016. Needless to say, the images are bright and clear using these disks. I still have one and will dig it out and take some photos soon. Lots going on at Ferrocell lately.