Hello Belgium:
If you want to give me a better idea of what your trying to do, I might be able to be of service.
I assume you have checked out the common sources such as Optical Dynamics,...
Type: Posts; User: eyesguy; Keyword(s):
Hello Belgium:
If you want to give me a better idea of what your trying to do, I might be able to be of service.
I assume you have checked out the common sources such as Optical Dynamics,...
Hi:
An Arc lamp is very critical inspection tool. You can simulate one buy going outside and focusing the sun through a lens you want to inspect onto a smooth white surface.
If you decide to...
Hi:
Can someone tell me how to calibrate a Humphery Lens Analyzer, Model 340?
Also, where can I get a manual for this machine?
Thanks,
eyesguy
Hi:
I have the equipment and technology to produce glass casting molds for people who cast their own lenses using Opticast, Optical Dynamics, etc., casting systems.
I can make flat-top...
Hi David:
Thank you for your reply. I recently completed an aspheric design for one of my clients and it was necessary to compromise the design in order to obtain acceptable performance in both...
Hi:
In general, if a single vision Rx already has an aspheric front (cx), can its optical performance, i.e., astigmatism, lateral color, etc. be improved by any "significant" amount by using an...
Hi Beth:
This might seem crazy, but you could try this. Make or buy two plus lenses -- one with the lowest index you can find and one with the highest. Except for index, they should be identical...
It's hard to explain if you are not familiar with ST mold production methods. It has to do with cutting the face angle on the fusing segment or bar stop on one-piece molds In both cases, you're...
Hi Garner:
Thanks for your reply. I'd prefer a spherical machine because of their simplicity. I guess I would consider a compound one depending on price, size, condition, etc.
Thanks,
eyesguy
Hi Harry:
A slight curve in the seg line is perfectly normal. As Shanbaum and Darryl have suggested, it's a geometry thing dealing with angle of view of a straight line on a spherical surface. The...
Hi:
I'm looking for a used sherical glass generator. If you have one or know a source for used equipment, I would appreciate a reply.
Thanks,
eyesguy
LauraH:
You got it! The important thing is the defect is not physical in the sense that it is a scratch, chip, etc. Rather, it is a localized area in the lens where the index of referaction is...
Hi:
Striae is a common defect name used by plastic (and glass) lens manufacturers. It represents anything in the body of the lens that alters the index of refraction. It can appear as fingers,...
Hi John R:
I went to the web-site you mentioned and could not find an on-line bookstore. What am I doing wrong?
Regards,
eyesguy
Thanks for your input everyone. I talked to an OD friend of mind and he said that -3.00 is a reasonably safe lower limit.
eyesguy
Good luck getting Jalie's book(s). I searched the web for a week before locating a used copy. Smith gives the same information and is easy to get.
eyesguy
This may seem like an odd question, but is there a rule of thumb about how flat the rear curve of an Rx can be before it begins to interfere with the wearer's eyelashes? For example, a plano back...
I agree with Steve--I generally don't worry about SA when trying to optimize a design. Astigmatism and Lateral Color are my errors of choice.
eyesguy
The idea to meet forum members at VE sounded like a good idea and I was looking forward to it. However, there seemed to be a lot more people than the forum sign-up list would indicate and it was not...
Hi Edgley:
To find SA:
Trace a ray from the object point and find the image distance L. Next, trace a paraxial ray from the same point and find its image distance l. Longitudinal SA = L-l. Hope...
Hi Spec:
If you have Excel, Download Darryl's "Optics Lite" . It will do what you need and then some. I could give you easy formulars for minus lenses, but plus lenses will give you fits if your...
Hi Jerry:
Here are a couple of sites that might help.
www.apomanet.org/links.htm
www.global.ihs.com
Regards,
eyesguy
My thanks to David W., Darryl M., and Steve M. for your fast reponse to my Mo Jalie posting. I look forward to seeing Darryl's spreadsheet. Thanks again guys!
eyesguy
HI:
One of the best works I have seen on base curve selection is "The Design Of a General Purpose Single Vision Lens Series" by John Davis, Henry Fernald, and Arline Rayner. I had the pleasure of...
I may be a new optiboarder, but I can't wait to meet you guys and gals!
eyesguy