Are your lens designs coming back from suppliers as "not manufacturable"?
Modern optical design software such as Zemax and CodeV are incredibly powerful tools for designing lenses. The user interfaces have simplified and automated many steps that used to be time-consuming. With these improvements comes a risk that a lens design may look great "on paper", but is not practical to make.
Here is a checklist to consider in a custom lens design to ensure it is manufacturable.
1) Check material selection:
Confirm the glass type is available with the supplier
Avoid high index glass if possible, they are prone to staining
2) Ensure lens geometry is within normal ranges:
Lens radii shouldn't be too long or too short
The ratio of lens diameter to center thickness
For small lenses, under 10 mm, between 1 and 5 is ideal
For larger lenses, a ratio of 3 to 20 is appropriate, and between 3 and 10 is ideal
The lens diameter-to-radius ratio should be less than 2
Lens edge thickness should be greater than 0.7mm min recommended for most lenses
3) Make sure the following specifications are not too tight or "over toleranced"
Surface power and irregularity
Centration or lens edge run-out
4) Ensure the lens can be tested properly:
Long or very short radii are a challenge
Are test plates in stock for radii selected?
Meniscus lenses should be avoided where the radii are nearly concentric
5) Additionally, check the following:
The mechanical holders and spacers needed are also manufacturable
The lens clear apertures within 10-15% of the edge, no smaller
Finally, Before getting too far into the lens design, it is always advisable to get feedback from your lens manufacturer.