I have on ocasion had several people attempt to sell us "in house lens moulding machines). We have declined for amoung other reasons our volume doesn't support it. However part of the hype from the sales people state it makes a "good mid-index lens."
My Question: What is thier mid-index material made of? Poly, polyurathane, urathane, CR-39(not) what?
Chip
From what I've seen it's a UV hardening resin, similar to the type used for Sunsensors. There are now two indexes 1.56 and the newer 1.523. Probably better off buying blanks.
They call it "monomer". It is a UV cure one-part polyurethane.
The Opticast material is pretty good. Unlike the other mid-index lenses (except trivex), this material is not brittle. It will pass the high-impact Z87 std at 2.0mm. It doesn't flake in a groove, and doesn't need a hard-coat.
It is a 1.534 index w/ an Abbe of 43.3.
the other mfg's (ODC) material tends to flake, in my estimation. It is also a UV cure polyurethane
Last edited by MarcE; 12-12-2008 at 12:25 AM.
Meaning that the in-office casting units have been offering Trivex all this time? We or our labs could have been rolling thier own with practically no cost all this time?
Chip
I know, those stats sound like Trivex. The Opticast monomer is more like trivex than it is like the 1.55/1.56 material. It's chemical resistant, more scratch resistant and less brittle than the 1.55/1.56.Originally Posted by chip anderson
It is however no match for trivex in the impact resistance department.
There is a group in France offering an inhouse casting system that is thermal cure and uses tape instead of gaskets. I know nothing about their cure time, hard coating method, etc but it looks interesting and likely less expensive than the ODC system.
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