Parabolic & Newtonian Telescope Mirrors
We make telescope primary mirrors in-house on commercial optical fabrication equipment — diamond curve generation, grinding, polishing, figuring, optical testing and coating, all under one roof. Controlling the whole process is what lets us hold a Strehl ratio of 0.950 or better and quote a delivery date we can meet.
Mirror making is paused. We are not taking orders for new telescope mirrors while the shop moves to Fresno, and expect to resume in fall 2027. Optical coatings return first, in January 2027. The prices below are our last published figures and are under revision.
How they are made
Every mirror is made here, on production machinery, not on shop-built equipment. The blank is diamond generated to the curve, then ground, polished and figured, tested, and coated in our own vacuum chamber. Nothing is subcontracted and nothing sits in someone else’s queue.
That matters for two reasons. Quality control is continuous rather than a hand-off inspection — a problem found at polishing is corrected at polishing. And delivery does not depend on a coating house scheduling us in, because the coater is thirty feet from the polisher.
What you get
Every standard mirror is made to the same specification:
- Figure
- Parabolic, to a Strehl ratio of 0.950 or greater at standard focal ratios. The usual diffraction-limited threshold is 0.80.
- Substrate
- Pyrex, priced with a plano — ground flat — back. Roughly a third the thermal expansion of plate glass, so it holds its figure while it cools to ambient.
- Thickness
- Semi-thin, balancing stiffness against cooling time. A thick blank holds its figure under its own weight but takes hours to reach ambient; a thin one cools fast but flexes in the cell. Custom thicknesses are available and may carry an additional charge.
- Focal ratio
- f/5 or slower as standard. Faster than f/5 adds 15% per half stop — a fast paraboloid departs further from a sphere and takes more figuring and testing to reach the same Strehl.
- Coating
- Standard aluminum in our own chamber, included in the price. Semi-enhanced, enhanced 96%, protected silver and gold are available at the difference in coating price for that size.
- Test data
- Each mirror ships with its measured figure — peak-to-valley wavefront error, Strehl ratio and our surface smoothness rating.
Prices
Mirror making is paused until fall 2027. These prices apply to work booked for the restart.
Standard parabolic mirrors
| Diameter (inches) | Substrate | Price |
|---|---|---|
| 4.25 | — | $1,330.00 |
| 6 | — | $1,570.00 |
| 8 | 1.1" substrate | $1,940.00 |
| 9 | 1.1" substrate | $2,150.00 |
| 10 | 1.3" substrate | $2,590.00 |
| 11 | 1.3" substrate | $2,920.00 |
| 12 | 1.5" substrate | $3,390.00 |
| 12.5 | 1.5" substrate | $3,560.00 |
| 13.1 | 1.5" substrate | $3,830.00 |
| 14 | 1.5" substrate | $4,880.00 |
| 14.25 | 1.5" substrate | $4,990.00 |
| 14.5 | 1.5" substrate | $5,140.00 |
| 15 | 1.625" substrate | $5,520.00 |
| 16 | 1.625" substrate | $6,370.00 |
| 17.5 | 1.625" substrate | $7,550.00 |
| 18 | 1.625" substrate | $8,380.00 |
| 20 | 1.625" substrate | $11,370.00 |
| 22 | 1.625" substrate | $13,020.00 |
| 24 | 1.625" substrate | $15,390.00 |
| 25 | 1.625" substrate | On request |
| 28 | 1.625" substrate | On request |
| 30 | 1.625" substrate | On request |
| 32 | 1.625" substrate | On request |
| 34 | 1.625" substrate | On request |
| 36 | 1.625" substrate | On request |
| 40 | 1.625" substrate | On request |
| 48 | 1.625" substrate | On request |
- Prices include a standard aluminum coating applied in our own chamber, up to our 22 inch coating capacity.
- Standard focal ratio is f/5 or slower. Faster than f/5 adds 15% per half stop.
- Substrate thicknesses are in the semi-thin range, with a plano ground flat back.
- Custom thicknesses are available on request; additional charges may apply.
- Sizes shown as on request are quoted individually.
Price list effective 2026-08-13.
Frequently asked questions
Are you making telescope mirrors at the moment?
No. Mirror making is paused while we move the shop to Fresno, and we expect to resume in the fall of 2027. Optical coatings come back first, in January 2027. The prices on this page are our last published figures and are under revision.
What is a parabolic mirror, and why does a Newtonian need one?
A spherical mirror does not bring parallel light to a single focus — rays striking the outer zones cross the axis nearer the mirror than rays near the center, which is spherical aberration. A paraboloid corrects that exactly for light arriving on axis, which is why every Newtonian primary of consequence is a parabola rather than a sphere. The faster the mirror, the more the two shapes differ and the more figuring it takes to get there.
What optical standard do your mirrors meet?
A Strehl ratio of 0.950 or greater at standard focal ratios. Strehl is the fraction of light the mirror puts into the theoretical diffraction pattern, so 0.95 means 95% of what a perfect optic of the same aperture would deliver. The widely used diffraction-limited threshold is 0.80; we test well past it.
What substrate do you use?
Pyrex, priced with a plano ground flat back. Pyrex has roughly a third the thermal expansion of plate glass, so it holds its figure while cooling to ambient instead of drifting through the first hour of an observing session.
How thick are your mirrors, and why?
Standard mirrors use substrates in the semi-thin range. It is a deliberate compromise: a thick blank is stiff and holds its figure under its own weight, but takes a long time to reach ambient temperature and shows tube currents while it does. A thin one cools quickly but flexes in its cell. Semi-thin balances the two. Custom thicknesses are available and may carry an additional charge.
Can you make a mirror faster than f/5?
Yes. Faster than f/5 adds 15% per half stop of speed. A fast paraboloid departs further from a sphere and needs more figuring and more testing to reach the same Strehl, and the price reflects the work rather than the glass.
Does the price include a coating?
Yes. Standard aluminum coating in our own chamber is included in the mirror price. If you want semi-enhanced, enhanced 96%, protected silver or gold instead, the difference is the coating price for that size.