Item specifics

Brand: Unbranded
Marked: National Oceanic
Type: Concave Optical Mirror
Diameter: 10 in
Thickness: 1-3/8 in
Focal Length: Approx. 94–95 in, calculated from measured sag
Focal Ratio: Approx. f/9.5
Surface Protection: Aqua protective coating / masking

Description

National Oceanic marked concave optical mirror.

Marked on edge: “National Oceanic” and “DIA. 10" x 1-3/8".”

Measurements:

• Diameter: 10"
• Thickness: 1-3/8"
• Concave depth/sag: approximately 0.066"–0.067", measured with a straight edge and feeler gauge
• Estimated focal length: approximately 94"–95"
• Estimated focal ratio: approximately f/9.5

The optical face is covered with an aqua protective coating/masking. A very small edge spot, approximately 1/16", was removed to confirm a polished reflective mirror surface underneath. The main optical face remains coated/protected and has not been stripped, cleaned, or handled.