All our objectives are guaranteed to have a minimum of .96 Strehl in green light and are optimized for the wavelengths where eye is most sensitive, 555 – 560 nm.

· Manufacturing specifications:
– Strehl ratio better than 96% at 532 nm.
– Wave front error p.t.v. is no more than 0.166 of wave-length at 532 nm.
– Surface finish: IV class according to 11141-84

· Dimensions of scratches and points/inclusions shall not exceed the following values:
· Scratches with less than 0.02 mm width:
– Number of scratches: less than 0.1 clear aperture
– Total length of scratches: less than 1 clear aperture.
· Points with less than 0.3 mm diameter:
– Number of points: less than 0.25 clear aperture
· Total area of all defects: less than 0.05 clear aperture (mm2)

· Multiple layer coatings on front and back surfaces. Reflectivity = 0.25%/surface.

· Slight color variations in the light reflected from anti-reflection coatings are allowed.

· Bubbles and inclusions in glass material are allowed under 0.5 mm diameter. Maximum number of bubbles and inclusions is 2 pieces per lens. Bubbles and inclusions under 0.03 mm diameter are disregarded.


Pal Gyulai
Optical Designer
CFF Telescopes

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