"Newtonian Mirrors made and certified in writing to be well within the most exacting, demanding Millies LaCroix tolerance - typically better than 1/10 wave on the wavefront - which is over twice as precise as the industry 1/4 wave standard." (See additional discussion under "Optical Talk" page at this website.)We only use precision annealed Schott Supremax-33 in the thicknesses noted on the pricelist page. Blanks are fine ground and flat on the backside with a round bevel. Thinner blanks are polished on the backside that is said to improve their strength and also to provide less friction against the mirror support pads. The face bevel is polished to improve contrast.
For the most discriminating planetary observers who prefer a more portable high-performance telescope we also offer 8” aperture F/7 and 10" or 12.5" aperture with an F/6 focal ratio, as the longer focal ratio makes it possible to consistently achieve wavefront peak-to-valley ratings of less than 1/20th wave with our known process capability.And for the most discriminating CCD and Videographers who prefer a faster focal ratio we are proud to announce a line of faster, high quality focal ratio mirrors in all sizes. Currently 12.5" and 16" F/4 mirrors are being produced. Please see our mirrors and mirror cells in stock for availability. Our product includes not only a precise mirror that produces simply the best performance possible, but also a certification containing the tolerance, measurement accuracy, and process controls that make this performance possible. We can provide a complete explanation with the certification that explains the methods used to calculate the numbers used and pertinent formulas. The data contained within the certification can be used to replicate conditions of test using attainable test methods, and thereby to confirm the accuracy of results provided. Testing and refiguring services are also available. For a test of your mirror, please send it properly wrapped and packed and insured with returned postage included. We handle coated mirrors properly; so don't worry about damage to the coating. Contact us if you're unsure about how to properly wrap it for shipment. For mirrors 16" diameter and under, please include $30.00 for this test. Mirrors 18" diameter and over include $50.00 for the test. This nominal fee will be applied to the refiguring cost should you wish to have that done. The longest focal length our shop can accommodate is 112-inches. Send in your uncoated mirror and a complete test will be done to include a photograph of the mirror’s internal condition using cross polarization. If you choose to have your mirror refigured and your glass is strain-free it will be fine ground on the back to our finish specifications and serialized, as are all of our mirrors. The price for refiguring is our current price for a new mirror, for your given size less 35%. It will be polished complete and spherical, then figured to our premium specifications and given all the care and effort our regular premium mirrors receive. It will essentially be a new, quality Lightholder Mirror. We also make 9, 18 and 27-point mirror cells that are available, ask for a quote with dimensions or supply your own dimensions to custom order to fit your particular mirror box.