Maitiro ekuderedza ruzha rwezvioni zvemafoto

Maitiro ekuderedza ruzha rwezvioni zvemafoto

Ruzha rwezvishandiso zvemafoto runosanganisira: ruzha rwemagetsi, ruzha rwekupisa, ruzha rwepfuti, ruzha rwe1/f uye ruzha rwebhandi rakakura, nezvimwewo. Kupatsanura uku kunongova kwakaoma. Panguva ino, tichaisa hunhu hweruzha hwakadzama uye kupatsanura kuti tibatsire munhu wese kunzwisisa zviri nani kukanganiswa kwemarudzi akasiyana-siyana eruzha pazviratidzo zvinobuda zvezvishandiso zvemafoto. Nekunzwisisa chete kwakabva ruzha ndipo patinogona kuderedza nekuvandudza ruzha rwezvishandiso zvemafoto, nokudaro tichigadzirisa chiyero chesignal-to-noise chesystem.

Ruzha rwepfuti kuchinja-chinja kunokonzerwa nehunhu hwakasiyana hwevatakuri vemagetsi. Kunyanya mumhedzisiro yemagetsi, apo mafotoni anorova zvikamu zvinonzwa chiedza kuti agadzire maerekitironi, kugadzirwa kwemaerekitironi aya kunoitika nekusarongeka uye kunoenderana nekugoverwa kwePoisson. Hunhu hwespectral hweruzha rwepfuti hwakatsetseka uye hahuna chekuita nehukuru hwefrequency, saka hunonziwo ruzha ruchena. Tsananguro yemasvomhu: Kukosha kwepakati pe root (RMS) kweruzha rwepfuti kunogona kuratidzwa se:

Pakati pavo:

e: Chaja yemagetsi (inenge 1.6 × 10-19 coulombs)

Dark: Rima rakasviba

Δf: Bandwidth

Ruzha rwekupfura runoenderana nehukuru hwemagetsi uye rwakagadzikana pama frequency ese. Mufomura, Idark inomiririra rima remagetsi rephotodiode. Kureva kuti, kana pasina chiedza, photodiode ine ruzha rwerima risingadiwe. Sezvo ruzha rwuripo kumberi kwe photodetector, rima remagetsi rakakura, ruzha rwe photodetector runowedzerawo. Dark current inokanganiswawo ne bias operating voltage ye photodiode, kureva kuti, bias operating voltage yakakura, dark current yakakura. Zvisinei, bias working voltage inokanganisawo junction capacitance ye photodetector, nokudaro ichikanganisa kumhanya uye bandwidth ye photodetector. Uyezve, bias voltage yakakura, kumhanya uye bandwidth zvakakura. Naizvozvo, maererano ne shot noise, dark current uye bandwidth performance ye photodiodes, dhizaini inonzwisisika inofanira kuitwa zvichienderana nezvinodiwa chaizvo zvepurojekiti.

2. Ruzha rwe1/f Runodzima

Ruzha rwe1/f, runozivikanwawo seruzha rwekupenya, runonyanya kuitika munzvimbo ine ruzha rwakaderera uye rune chekuita nezvinhu zvakaita sekukanganisika kwezvinhu kana kuchena kwenzvimbo. Kubva padhayagiramu yayo yespectral, zvinoonekwa kuti density yayo ye power spectral yakaderera zvakanyanya munzvimbo ine ruzha rwakakwirira pane munzvimbo ine ruzha rwakaderera, uye pakuwedzera kwe100 nguva mufrequency, ruzha rwespectral density runoderera ne10 nguva. Simba respectral density re1/f noise rinoenderana nefrequency, kureva:

Pakati pavo:

SI(f) : Ruzha rwesimba reruzha

Ini: Zvazvino

f: Kuwanda

Ruzha rwe1/f rwakakosha muhuwandu hwemafrequency akaderera uye runodzikira sezvo mafrequency achiwedzera. Hunhu uhwu hunoita kuti ive chinhu chikuru chinovhiringidza mashandisirwo emafrequency akaderera. Ruzha rwe1/f uye ruzha rwebroadband zvinonyanya kubva kuvoltage noise ye operational amplifier mukati me photodetector. Kune mamwe manyuko mazhinji eruzha anokanganisa ruzha rwe photodetectors, senge power supply noise ye operational amplifier, current noise, uye thermal noise ye resistance network mu gain ye operational amplifier circuits.

3. Ruzha rwemagetsi nemagetsi emuchina wekufambisa magetsi: Kuwanda kwemagetsi nemagetsi emagetsi zvinoratidzwa mumufananidzo unotevera:

Mumacircuits e operational amplifier, ruzha rwemagetsi runokamurwa kuita ruzha rwemagetsi rwe in-phase uye ruzha rwemagetsi rwe inverting. Ruzha rwemagetsi rwe in-phase i+ runoyerera kuburikidza ne source internal resistance Rs, zvichigadzira ruzha rwemagetsi rwakaenzana u1= i+*Rs. I- Ruzha rwemagetsi rwe inverting runoyerera kuburikidza ne gain equivalent resistor R kuti rugadzire ruzha rwemagetsi rwakaenzana u2= I-* R. Saka kana RS yemagetsi yakakura, ruzha rwemagetsi rwakashandurwa kubva kurunyararo rwemagetsi rwakanyanyawo. Saka, kuti ruwedzere ruzha rwuri nani, ruzha rwemagetsi (kusanganisira resistance yemukati) inzira yakakosha yekuvandudza. Kuwanda kwespectral yeruzha rwemagetsi hakuchinji nekuchinja kwema frequency futi. Saka, mushure mekuwedzerwa ne circuit, iyo, se dark current ye photodiode, inogadzira ruzha rwe shot rwe photodetector zvakakwana.

4. Ruzha rwekupisa rwe network yekuramba (amplification factor) yedunhu re operational amplifier rinogona kuverengerwa uchishandisa fomula inotevera:

Pakati pavo:

k: Boltzmann constant (1.38 × 10-23J/K)

T: Tembiricha Yakazara (K)

R: Ruzha rwekupisa rweResistance (ohms) rune chekuita netembiricha uye kukosha kwekudzivirira, uye spectrum yaro yakati sandara. Zvinogona kuonekwa kubva mufomura yekuti kana kukosha kwekudzivirira kuwana kwakakura, ruzha rwekupisa runowedzerawo. Kana bandwidth yakakura, ruzha rwekupisa ruchavawo rukuru. Saka, kuti ive nechokwadi chekuti kukosha kwekudzivirira uye kukosha kwebandwidth kunosangana nezvinodiwa zvekuwana uye zvinodiwa zvebandwidth, uye pakupedzisira zvinodawo ruzha rwakaderera kana chiyero chepamusoro chesignal-to-noise, kusarudzwa kwegain resistor kunofanirwa kufungwa nekungwarira uye kuongororwa zvichienderana nezvinodiwa chaizvo zvepurojekiti kuti uwane chiyero chakakodzera chesignal-to-noise chesystem.

Pfupiso

Tekinoroji yekuvandudza ruzha ine basa guru mukusimudzira mashandiro ezvioni zvemagetsi nemidziyo yemagetsi. Kunyatsojeka kunoreva ruzha rwakaderera. Sezvo tekinoroji ichida kunyatsojeka kwakanyanya, zvinodiwa zveruzha, chiyero chesignali-ku-ruzha, uye simba reruzha rakaenzana rezvioni zvemagetsi zviri kuramba zvichikwira.