Pehea e hōʻemi ai i ka walaʻau o nā photodetectors

Pehea e hōʻemi ai i ka walaʻau o nā photodetectors

ʻO ka walaʻau o nā photodetectors ka mea nui: ka leo o kēia manawa, ka walaʻau wela, ka leo pana, ka walaʻau 1/f a me ka walaʻau ākea, a me nā mea ʻē aʻe. I kēia manawa, e hoʻolauna mākou i nā hiʻohiʻona leo kikoʻī a me ka hoʻokaʻawale ʻana e kōkua i ka poʻe āpau e hoʻomaopopo maikaʻi i ka hopena o nā ʻano leo like ʻole i nā hōʻailona puka o nā photodetectors. Ma ka hoʻomaopopo wale ʻana i nā kumu o ka walaʻau hiki iā mākou ke hōʻemi maikaʻi a hoʻomaikaʻi i ka walaʻau o nā photodetectors, a laila e hoʻonui i ka ratio signal-to-noise o ka ʻōnaehana.

ʻO ka walaʻau kiʻi he ʻano loli ma muli o ke ʻano ʻokoʻa o nā mea lawe uku. ʻOi loa i ka hopena photoelectric, i ka wā e hahau ai nā kiʻi kiʻi i nā mea photosensitive e hoʻohua i nā electrons, ʻo ka hoʻokumu ʻana o kēia mau electrons he maʻamau a kūlike me ka puʻunaue Poisson. ʻO nā hiʻohiʻona hiʻohiʻona o ka leo pana he pālahalaha a kūʻokoʻa i ka nui o ke alapine, a no laila ua kapa ʻia ʻo ia ka leo keʻokeʻo. Ka wehewehe makemakika: Hiki ke hōʻike ʻia ke kumu kumu mean square (RMS) o ka walaʻau pana e like me:

Ma waena o lākou:

e: Uku uila (ma kahi o 1.6 × 10-19 coulomb)

Idark: Ke au pouli

Δf: Kaʻeleʻele

Kūlike ka leo pana i ka nui o ke au a paʻa i nā alapine a pau. I loko o ke ʻano, hōʻike ʻo Idark i ka pōʻeleʻele o ka photodiode. ʻO ia hoʻi, i ka nele o ka mālamalama, makemake ʻole ka photodiode i ka leo ʻeleʻele o kēia manawa. E like me ka leo maʻamau ma ka hope loa o ka photodetector, ʻoi aku ka nui o ke au ʻeleʻele, ʻoi aku ka nui o ka walaʻau o ka photodetector. Hoʻopili pū ʻia ke au pōʻeleʻele e ka volta hana bias o ka photodiode, ʻo ia hoʻi, ʻoi aku ka nui o ka uila hana bias, ʻoi aku ka nui o ka pōʻeleʻele. Eia nō naʻe, pili pū ka uila hana bias i ka junction capacitance o ka photodetector, a laila e hoʻohuli i ka wikiwiki a me ka bandwidth o ka photodetector. Eia kekahi, ʻoi aku ka nui o ka voltage bias, ʻoi aku ka nui o ka wikiwiki a me ka bandwidth. No laila, ma ke ʻano o ka leo pana, ka pōʻeleʻele a me ka hana bandwidth o nā photodiodes, pono e hoʻokō ʻia ka hoʻolālā kūpono e like me nā koi o ka papahana maoli.

2. 1/f Ka halulu ʻā

ʻO ka walaʻau 1/f, ʻike ʻia hoʻi ʻo ka leo flicker, ʻike nui ʻia ma ke ʻano haʻahaʻa haʻahaʻa a pili i nā mea e like me nā hemahema waiwai a i ʻole ka maʻemaʻe o ka ʻili. Mai kona kiʻikuhi spectral hiʻona, ua hiki ke ike i kona mana spectral density mea nui uuku i loko o ka kiʻekiʻe-alapine laulā ma mua o ka haʻahaʻa-alapine laulā, a no kēlā me kēia 100 manawa hoʻonui i ka alapine, ka spectral density leo linearly emi e 10 manawa. ʻO ka mana spectral density o ka leo 1/f ua like like me ka alapine, ʻo ia hoʻi:

Ma waena o lākou:

SI(f): Ka halulu mana spectral density

I: I kēia manawa

f: Ka pinepine

He mea koʻikoʻi ka walaʻau 1/f i ka laulā haʻahaʻa a nāwaliwali i ka piʻi ʻana o ka alapine. ʻO kēia hiʻohiʻona ke kumu nui o ke keakea ʻana i nā noi haʻahaʻa haʻahaʻa. ʻO ka walaʻau 1/f a me ka walaʻau ākea ākea mai ka leo uila o ka mea hoʻonui hana i loko o ka photodetector. Nui nā kumu walaʻau ʻē aʻe e pili ana i ka walaʻau o nā photodetectors, e like me ke kani o ka mana o nā mea hoʻonui hana, ka walaʻau o kēia manawa, a me ka walaʻau wela o ka ʻoihana kūʻē i ka loaʻa ʻana o nā kaʻa amplifier hana.

3. Voltage a me ka leo o kēia manawa o ka mea hoʻonui hana: Hōʻike ʻia ka volta a me nā density spectral o kēia manawa ma kēia kiʻi.

I nā kaapuni amplifier hana, ua hoʻokaʻawale ʻia ka walaʻau o kēia manawa i ka leo o kēia manawa a me ka leo hoʻohuli i kēia manawa. Ke kahe nei ka leo o kēia manawa i+ ma ke kumu kū'ē kū i loko Rs, e hoʻopuka ana i ka leo uila like u1= i+*Rs. I- Ke hoʻohuli nei i ka walaʻau o kēia manawa e kahe ana ma o ka loaʻa ʻana like resistor R e hoʻohua i ka leo uila like u2= I-* R. No laila, i ka nui o ka RS o ka lako mana, ua nui loa ka leo uila i hoʻololi ʻia mai ka walaʻau o kēia manawa. No laila, no ka hoʻonui ʻana i ka walaʻau ʻoi aku ka maikaʻi, ʻo ke kani ʻana o ka mana (me ke kūpaʻa kūloko) ʻo ia hoʻi kahi kuhikuhi nui no ka optimization. ʻAʻole loli ka mānoanoa spectral o ka walaʻau i kēia manawa me nā ʻano like ʻole. No laila, ma hope o ka hoʻonui ʻia ʻana e ke kaapuni, ʻo ia, e like me ka pōʻeleʻele o ka photodiode, hoʻokumu piha i ka leo pana o ka photodetector.

4. Hiki ke helu ʻia ka walaʻau wela o ka ʻupena kū'ē no ka loaʻa (ka mea hoʻonui) o ke kaapuni amplifier hana me ka hoʻohana ʻana i kēia ʻano:

Ma waena o lākou:

k: Boltzmann mau (1.38 × 10-23J/K)

T: Ka Mahana Loa (K)

R: Pili ka walaʻau wela (ohms) i ka mahana a me ka waiwai kū'ē, a paʻa kona kiko. Hiki ke ʻike ʻia ma ke ʻano o ka nui o ka waiwai kūʻē o ka loaʻa, ʻoi aku ka nui o ka walaʻau wela. ʻO ka nui o ka bandwidth, ʻoi aku ka nui o ka leo wela. No laila, e hōʻoia i ka loaʻa ʻana o ka waiwai kūʻē a me ka waiwai bandwidth i nā koi loaʻa a me nā koi bandwidth, a i ka hopena e koi aku i ka haʻahaʻa haʻahaʻa a i ʻole kiʻekiʻe signal-to-noise ratio, pono e noʻonoʻo maikaʻi ʻia ke koho ʻana i nā resistors loaʻa e pili ana i ka pono o ka papahana e hoʻokō i ka lākiō hōʻailona maikaʻi loa o ka ʻōnaehana.

Hōʻuluʻulu manaʻo

He mea nui ka ʻenehana hoʻomaikaʻi noise i ka hoʻonui ʻana i ka hana o nā photodetectors a me nā mea uila. ʻO ke kikoʻī kiʻekiʻe ke ʻano o ka walaʻau haʻahaʻa. Ke koi nei ka ʻenehana i ka pololei kiʻekiʻe, ʻoi aku ka kiʻekiʻe o nā koi no ka walaʻau, ka lākiō hōʻailona-a-noise, a me ka mana leo like o nā photodetectors.