Try to bring a star image to focus.
Advantages are: focusing attention on one side then the other, unlike the Couder Mask where you have to watch both sides of the mask simultaneously; a poor curve with zones is readily apparent.
I abandoned the concept that mind power: into the 21st century john kehoe.pdf there is any acceptable tolerance in the zonal readings.Challenge yourself : Fight or flight.ChickenEgypt: Secret of five GodsEgyptian AddictionEgyptian BallEgyptian Settlement 2: New WorldsEgypt II: The Heliopolis ProphecyEgypt III: The Fate of RamsesEgypt Picross: Pharaoh's RiddlesEgypt Solitaire Match 2 CardsEl Dorado QuestElementals: The Magic KeyElementary My Dear MajestyElementsElf Bowling: Hawaiian VacationElf Bowling 7 1/7: The Last InsultElias the.Zonal Irregularities I discovered by accident after washing a mirror in warm water that the Ronchi test of a temporarily heated mirror makes minor zonal irregularities more obvious.I place the mirror back on the lap, rotating and moving every few seconds, until the glass and lap have equilibrated to the same temperature.Depending on where the grating is placed, acs smart card reader driver installation zones will be closer or further away from the grating, making the bands tighter or conversely more spreadout.Geometric based methods that calculate the path of the reflected light rays across the mirror face are popular and have a long history.'Final' means that the mirror forms an excellent high power star image.Fixing zones It's a rule of thumb in star testing driven parabolizing (using either real stars or indoor artificial stars) to 'polish the zone that focuses long'.I start with mirror on top of a full sized or oversized lap, but only execute the extreme chordal strokes at the edge - I do not stroke through center.
By the way, I saw the high zone is the star test but judged it extremely minor - the mirror was more than good enough, and I was able to suspect the zone in the Ronchi test with very careful inspection after the fact.
Mirror makers that used the star test or the interferometer test consistently make better mirrors.
Parabolizing fast mirrors with oversized laps Researching further, I found that Brashear mentioned oversized laps as a standard technique in the late 1800's.Beyond The Test Methods What are the realities that shine through the fog?The full form of the Caustic test measures both the 'x' and the 'y' displacement, computing the location of focus.Also check out the holographic mask test.This is the beginning of mirror making wisdom.