Andover Corporation

Andover Corporation designs and makes custom optical filters and coatings in New Hampshire, United States. Its products work from the ultraviolet at 193 nanometres to the far infrared at 15 micrometres. The company has about five decades of experience, and it carries out production in its own facility.

The filters serve aerospace, defence, medical and environmental customers. Other markets include astronomy, LiDAR, biomedical work, machine vision and semiconductors. The company says its filters give strong transmission, durability and stability for mission-critical uses.

The main filter lines include bandpass filters, neutral density filters, infrared filters, ultraviolet filters and edge filters, which pass or block light above or below a set wavelength. It also makes astronomy filters, including Johnson and Bessell, Kron-Cousins and Sloan types, and filters that protect image quality. Specialty items cover colour glass filters, heat control filters, dichroic filters, calibration filter sets, beamsplitters and prisms.

Andover also offers coating services. These include anti-reflective coatings from 193 nanometres to 15 micrometres, which cut reflection to under 0.1 percent at angles up to 50 degrees. It also applies infrared AR coatings, dual-band coatings, fibre tip coatings, diamond-like carbon coatings and chalcogenide coatings. Fabrication services cover optical assemblies, polishing, and high-volume production. Testing includes metrology, interferometry and verification.

Customers can buy standard parts, semi-custom parts or fully custom designs. The company supports prototypes as well as large production runs. It also sells surplus filters at reduced cost, including bandpass, edge and infrared types. Other items include infrared windows and substrates, optical mounts, filter wheels, cryolite evaporation material and epoxies.

In 2026 the company was named New Hampshire Small Business Exporter of the Year. It sells through an online store and works with distributors worldwide. Andover also sponsors a local youth club.

Services

• Optical bandpass filters
• Neutral density filters
• Infrared and ultraviolet filters
• Edge filters
• Astronomy filters
• Anti-reflective coatings
• Optical fabrication and polishing
• Metrology and interferometry
• Custom prototyping
• Surplus filters