DFM Engineering, Inc.
1035 Delaware Ave. Unit D
Longmont, CO 80501
Phone: 303-678-8143
Fax: 303-772-9411


Telescope Optics

telescope optics
Telescope Optical Tube Assembly Sample

The optical system in every DFM telescope is custom-created to meet customer specifications. Even the standard optics are held to rigorous DFM Engineering quality standards, as they are an extremely critical element of the DFM Telescope Optics system.

Lens Figuring

Mirrors larger than 32" are manufactured and tested at the DFM Engineering Optical Facility. This ensures incident light is contained within a minimum of 0.6 arc seconds.

DFM concentrates on fast, highly aspheric primary mirrors. Mirrors are typically 1.3-m F/2.3 mirrors for the wide field F/4 telescopes. These mirrors have a surface departure from the best fit sphere of 60 waves. DFM has completed five 1.3-m primary mirrors, a 1-m primary mirror, and a 1.3-m Hindle sphere in the optics shop.

Also, all primary and secondary mirror finishes are tested at DFM so as to be within proper range.

field corrector diagram
3 Element Field Corrector Diagram

DFM has also made several field corrector elements which are fourth order (Schmidt) type lenses that are used with the 1.3-m F/4 wide field telescopes. A 3 element field corrector is featured in the ATLAS Optical Tube Assembly (Asteroid Tracker), also manufactured at DFM.

The DFM Optics Shop uses two large optical flats (0.9-m and 1.6-m), several smaller flats, an interferometer, various test fixtures, and many tools. Also a 2 ton variable speed electric hoist and a gantry crane allows for safe and efficient handling of large optics.

Mirror Polishing

Mirrors larger than 32" are manufactured within the DFM Engineering Optical Facility. The optical shop capabilities have included a variety of large mirror sizes with multiple 51" mirrors adhering to critical customer specifications.

Since the quality of the mirror is directly related to the light gathering power and ability to resolve detail, DFM technicians take extreme care in the process of grinding, polishing, testing, and documenting, the product.

Optics Testing

The optical facility is staffed with expert technicians that deliver large quality optics typically used in telescopes. However, DFM Engineering has produced multiple modern scientific instruments requiring excellent optics in addition to telescopes. The list includes: satellite trackers, beam directors, lidar scanners, and heliostats.

Mirror handling systems designed specifically to safely allow technicians to move, reinstall and collimate the optics are a significant feature of the complete customer satisfaction provided by DFM Engineering.


•  Standard Features

•  Custom Features

•  Observatory Dome & Pier