我支自製鏡似乎有散光現象,即係話佢個像差唔係旋轉對稱咁,反而只係某一個方向出現較嚴重像差.
我剛拋好光,試鏡時係無發現到呢個問題的,同埋不對稱地出現散光似乎都不太容易,所以我估計呢個問題的出現,在於主鏡玻璃的內部應力在這三年內使到鏡面變形.
打算遲d重新再拋光同返鍍,相信之後內部應力的問題會有改善.
(以上的只是估計,當然有可能是當年無試真塊鏡,本來已有不對稱的散光啦!)
自製鏡散光
Dear ATMs,
All glass nowadys manufactured by floatation method. The stress inside the glass is prcaticaly zero, you can't get a piece of glass with stress.
I have been using my 20 inch mirror for 6 years, travelling to different parts of the world for star gazing. It is packed inside a small suit case with unimaginable forces on it but there is absolutely no signs of astigatism .
So you have an astigmatism problem due to careless execution in your earlier polishing process, ot due to poor design of your mirror support. The galss can't change its shape by itself once figured.
Chan Yuk Lun
All glass nowadys manufactured by floatation method. The stress inside the glass is prcaticaly zero, you can't get a piece of glass with stress.
I have been using my 20 inch mirror for 6 years, travelling to different parts of the world for star gazing. It is packed inside a small suit case with unimaginable forces on it but there is absolutely no signs of astigatism .
So you have an astigmatism problem due to careless execution in your earlier polishing process, ot due to poor design of your mirror support. The galss can't change its shape by itself once figured.
Chan Yuk Lun
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