22/04/22ʻO ka Dark Signal Non-Uniformity (DSNU) kahi ana o ke kiʻekiʻe o ka hoʻololi kūʻokoʻa o ka manawa ma ke kua o ke kiʻi kamera. Hāʻawi ia i kahi hōʻailona helu koʻikoʻi o ka maikaʻi o kēlā kiʻi hope, e pili ana i nā hiʻohiʻona a i ʻole nā hale i hiki ke loaʻa i kekahi manawa.
Ma ke kiʻi haʻahaʻa haʻahaʻa, hiki ke lilo ke ʻano o ke kāʻei kua i mea nui. Inā ʻaʻohe kiʻi paʻi kiʻi ma ka pahupaʻikiʻi, ʻaʻole hōʻike pinepine ʻia nā kiʻi i loaʻa i nā waiwai pika o 0 mau pae hina (ADU). Loaʻa ka waiwai 'offset', e like me 100 mau pae hina, e hōʻike ʻia e ke kāmela ke loaʻa ʻole ke kukui, hoʻohui a hōʻemi paha i ka mana o ka walaʻau ma ke ana. Eia nō naʻe, me ka ʻole o ka calibration a me ka hoʻoponopono ʻana, hiki ke hoʻololi ʻia mai ka pixel a i ka pixel i kēia waiwai offset paʻa. Kapa ʻia kēia ʻano hoʻololi ʻo 'Fixed Pattern Noise'. Hōʻike ka DNSU i ka nui o kēia walaʻau paʻa. Hōʻike ia i ka ʻokoʻa maʻamau o nā koina offset pixel, ana ʻia i nā electrons.
No nā kiʻi kiʻi haʻahaʻa haʻahaʻa, ʻo DSNU ka mea maʻamau ma lalo o 0.5e-. ʻO ia hoʻi, no nā noi haʻahaʻa a i ʻole nā mālamalama kiʻekiʻe me nā haneli a i ʻole mau tausani o nā kiʻi i hopu ʻia i kēlā me kēia pika, ʻaʻole i ʻike ʻia kēia hāʻawi walaʻau. ʻOiaʻiʻo, no nā noi māmā haʻahaʻa pū kekahi, hāʻawi ʻia ka DSNU ma mua o ka leo heluhelu o ke kāmela (maʻamau 1-3e-), ʻaʻole paha e pāʻani kēia walaʻau kumu paʻa i ka maikaʻi o ke kiʻi.
Eia naʻe, ʻaʻole ʻo DSNU kahi hiʻohiʻona kūpono o ka walaʻau kumu paʻa, no ka mea ʻaʻole hiki ke hopu i ʻelua mau mea nui. ʻO ka mea mua, hiki i nā kāmela CMOS ke hōʻike i nā hiʻohiʻona i kūkulu ʻia i kēia hoʻololi offset, pinepine i ke ʻano o nā kolamu o nā pika e ʻokoʻa ana kekahi i kekahi i ko lākou waiwai offset. ʻOi aku ka ʻike o kēia walaʻau 'Fixed Pattern Column Noise' i ko mākou maka ma mua o ka walaʻau i kūkulu ʻole ʻia, akā ʻaʻole i hōʻike ʻia kēia ʻokoʻa e ka waiwai DSNU. Hiki ke ʻike ʻia kēia mau kolamu kiʻi ma ke kua o nā kiʻi māmā haʻahaʻa loa, e like me ka wā i ʻike ʻia ka hōʻailona ma lalo o 100 photo-electrons. Ke nānā ʻana i kahi kiʻi 'bias', ʻo ke kiʻi i hana ʻia e ka pahupaʻikiʻi me ka ʻole o ka mālamalama, e ʻae iā ʻoe e nānā i ke ʻano o ka walaʻau kumu.
ʻO ka lua, i kekahi mau hihia, hiki ke hilinaʻi ʻia nā ʻano like ʻole o ka offset i ka manawa, e ʻokoʻa ana mai kekahi kiʻi a i kekahi. Ke hōʻike nei ʻo DSNU i ka hoʻololi kūʻokoʻa manawa, ʻaʻole i hoʻokomo ʻia kēia mau mea. ʻO ka nānā ʻana i ke kaʻina o nā kiʻi bias e ʻae iā ʻoe e nānā i ke ʻano o ka walaʻau o ke kumu hoʻohālike e pili ana i ka manawa.
E like me ka mea i hōʻike ʻia, ʻaʻole e lilo ka DSNU a me nā ʻano hoʻololi hope i mea koʻikoʻi no nā noi waena a me ke kukui kiʻekiʻe me nā tausani kiʻi kiʻi no kēlā me kēia pika, no ka mea e ʻoi aku ka ikaika o kēia mau hōʻailona ma mua o nā ʻano like ʻole.
