Telescope Mirrors in Stock
From time to time we finish optics that have no destination — spares from a contract run, or shop test fixtures figured into telescope mirrors. They are not seconds. They are made to the same standard as everything else that leaves here, and sold at a price that reflects the fact that you are choosing from what exists rather than specifying it yourself.
Available now
No optics are listed for sale at the moment. We hold finished mirrors now, but we are not set up to sell and ship them until the new Fresno shop opens in January 2027. Inventory will be posted here as it becomes available.
If you are looking for something specific, tell us what you need — diameter, focal ratio and the telescope it is going into. We will get in touch when a matching optic comes up, before it is listed publicly.
In the meantime, we can make one to your specification. See telescope mirrors for what we build and what it costs.
Where stock optics come from
Contract work is normally run with spares. Figuring an extra optic alongside the others costs a fraction of what it costs to start a second run if one is lost to handling or to a coating fault, so a batch of six is rarely a batch of exactly six. The spares that are never called for have nowhere in particular to go.
The rest begin as test fixtures. Glass used in the shop for setting up and checking equipment eventually reaches the end of its working life as a fixture while still being a perfectly sound blank. Rather than shelve it, we figure it into a telescope mirror.
Neither route produces a reject. An optic that fails inspection is reworked or scrapped — it is never quietly moved to a stock list. What you give up by buying from stock is choice of specification, not quality: the diameter and focal length are whatever that optic happens to be.
The standard they are made to
Every stock optic goes through the same process as a custom order — the same grinding, polishing and figuring, and the same optical test at the end. Each listing carries its measured figure, and each optic ships with the test report: peak-to-valley wavefront error, Strehl ratio, and our surface smoothness rating. You are not asked to take our word for what a mirror does.
Where an optic is offered bare, you can have it coated to any of our standard specifications before it ships — see coatings for the options and what each one reflects, and coating data for the measured reflectivity curves.
Optics that have already been coated as part of a contract run are listed with the coating they carry.
How buying will work
When inventory goes up, stock optics will be bought through the customer portal, the same system that handles coating orders. You will see the optic's full specification and test data, add any coating or center spotting you want, and get a total including packing and carriage before you commit to anything.
Optics are packed the way we insist customers pack theirs — one optic per carton, cushioned against movement. How we pack optics explains why that matters more than any other single thing about shipping glass.
Questions
Are stock mirrors seconds or rejects?
No. A stock optic is one that was made, not one that failed. Every mirror we list has been through the same grinding, polishing, figuring and testing as a custom order, and is measured against the same standard before it is offered. What a stock optic lacks is not quality — it is your choice of specification. You are buying a mirror that already exists, at whatever diameter and focal length it happens to be.
Where do stock optics come from?
Two places. Contract work is normally run with spares, because figuring an extra optic alongside the others costs far less than starting a second run if one is lost to handling or coating; spares that are never called for have nowhere to go. The rest are test fixtures — glass used in the shop that reaches the end of its working life as a sound blank, which we then figure into a telescope mirror rather than shelve.
Do stock mirrors come with test data?
Yes. Each optic is listed with its measured figure, and ships with the same test report we produce for custom work — peak-to-valley wavefront error, Strehl ratio and a surface smoothness rating. You are not asked to take our word for what a mirror does.
Are stock mirrors coated?
It varies, and each listing says which. Some are offered bare so you can choose a coating; others are already coated from a contract run. A bare optic can be coated to any of our standard specifications before it ships.
When will inventory be listed?
When the Fresno shop opens in January 2027. We hold finished optics now, but we are not set up to sell and ship them until the new facility is running. Listing optics we cannot yet dispatch would waste your time.
Can I reserve an optic before you reopen?
Get in touch and tell us what you are looking for — diameter, focal ratio and intended telescope. We will contact you when something matching appears, before it is listed publicly.