Commercial astronomical telescope optics development has followed a straight tangent for decades now. Focal lengths have shortened while image sizes have grown. Refractive telescopes houses five or even six lenses, making them more and more like over-sized camera optics, driving up manufacturing costs fast. Producing more and more expensive and generic products for smaller and smaller range of enthusiasts does not pay back development.
Stock optical components are very attractive option for a developer. You get parts ASAP, keep prototyping costs down and one gets fitting optomechanical parts to go, and you can do all by yourself as well. Then again, there are whole factories spewing out same parts to your competitor, with same instructions and howto’s. So it comes down to this: what SPECIAL can you do with stock optical parts? Turns out, quite a lot. However, they might need an optical engineer to pull them off. I’ll go through some examples of common tripping points of stock optical components, and a short description on how an optical designer can overcome them.
For prototyping purposes, our company engages in creating different applications with stock optics. This time we focused on a fast MWIR (3-5μm) optics. Available stock optics are severely limited, but we managed to pull off a 50° FFOV diffraction-limited objective. Field would benefit from custom optics, but most prototyping and proof-of-concepts are quite possible with just stock optics.
Several manufacturers can provide pre-fabricated optical parts for very reasonable prices. For a customer they are very attractive, but for the designer they are that sinister oppressive path through a damp dark forest after reading Lovecraft novels – how can anything innovative come out of something as coarse as pre-fabricated parts? Client is demanding the impossible! Or when viewed with a positive attitude, just kicking you forward. Pre-fabricated components design is very attractive and here to stay, so best to make the best of it. Here I design some basic finite conjugate objectives with pre-fabricated parts and see their limitations first-hand.
Originally published 15.5.2014 by Jani Achrén.