Momwe mungachepetsere phokoso la zida zowunikira zithunzi

Momwe mungachepetsere phokoso la zida zowunikira zithunzi

Phokoso la ma photodetector limaphatikizapo makamaka: phokoso lamakono, phokoso la kutentha, phokoso lowombera, phokoso la 1/f ndi phokoso la broadband, ndi zina zotero. Kugawa kumeneku ndi kovuta kwambiri. Nthawi ino, tipereka mawonekedwe a phokoso mwatsatanetsatane komanso magulu kuti tithandize aliyense kumvetsetsa bwino momwe mitundu yosiyanasiyana ya phokoso imakhudzira zizindikiro zotulutsa za ma photodetector. Pokhapokha pomvetsetsa magwero a phokoso ndi pomwe tingachepetse bwino ndikukonza phokoso la ma photodetector, potero kukonza chiŵerengero cha chizindikiro-kwa-phokoso cha dongosolo.

Phokoso la mfuti ndi kusinthasintha kwachisawawa komwe kumachitika chifukwa cha mtundu wosiyana wa zonyamulira mphamvu. Makamaka mu mphamvu ya photoelectric, pamene ma photon agunda zigawo zomvera kuwala kuti apange ma elekitironi, kupanga ma elekitironi amenewa kumachitika mwachisawawa ndipo kumagwirizana ndi kugawa kwa Poisson. Makhalidwe a phokoso la mfuti ndi athyathyathya komanso osagwirizana ndi kukula kwa ma frequency, motero amatchedwanso phokoso loyera. Kufotokozera kwa masamu: Mtengo wa root mean square (RMS) wa phokoso la mfuti ukhoza kufotokozedwa motere:

Mwa iwo:

e: Chaji yamagetsi (pafupifupi 1.6 × 10-19 coulombs)

Idark: Mphepo yamdima

Δf: Bandwidth

Phokoso la kuwombera limagwirizana ndi kukula kwa mphamvu yamagetsi ndipo limakhala lokhazikika pama frequency onse. Mu fomula, Idark imayimira mphamvu yamdima ya photodiode. Izi zikutanthauza kuti, popanda kuwala, photodiode imakhala ndi phokoso lamphamvu losafunikira. Monga phokoso lamkati lomwe lili kumapeto kwenikweni kwa chowunikira zithunzi, mphamvu yamdima ikakula, phokoso la chowunikira zithunzi limakulanso. Mphamvu yamdima imakhudzidwanso ndi mphamvu yamagetsi ya photodiode, ndiko kuti, mphamvu yamagetsi yamagetsi ya bias ikakula, mphamvu yamdima imakulanso. Komabe, mphamvu yamagetsi ya bias imakhudzanso mphamvu ya chowunikira zithunzi, motero zimakhudza liwiro ndi bandwidth ya chowunikira zithunzi. Komanso, mphamvu yamagetsi ya bias ikakula, liwiro ndi bandwidth zimakulanso. Chifukwa chake, pankhani ya phokoso la kuwombera, mphamvu yamdima ndi magwiridwe antchito a bandwidth a ma photodiode, kapangidwe koyenera kuyenera kuchitidwa malinga ndi zofunikira zenizeni za polojekitiyi.

2. Phokoso Lozimitsa la 1/f

Phokoso la 1/f, lomwe limadziwikanso kuti flicker noise, limapezeka makamaka pamlingo wotsika ndipo limakhudzana ndi zinthu monga zolakwika pazinthu kapena kuyera kwa pamwamba. Kuchokera pa chithunzi chake cha spectral, zitha kuwoneka kuti kuchuluka kwa mphamvu ya spectral ndi kochepa kwambiri pamlingo wapamwamba kuposa pamlingo wotsika, ndipo pakuwonjezeka kwa nthawi 100, phokoso la spectral density limachepa molunjika ndi nthawi 10. Kuchuluka kwa mphamvu ya spectral ya phokoso la 1/f ndi kosiyana ndi kuchuluka, ndiko kuti:

Mwa iwo:

SI(f) : Kuchuluka kwa ma spectral a mphamvu ya phokoso

Ine: Zamakono

f: Kuchuluka kwa nthawi

Phokoso la 1/f ndi lofunika kwambiri pamlingo wotsika ndipo limafooka pamene kuchuluka kwa ma frequency kukukwera. Khalidweli limapangitsa kuti likhale gwero lalikulu la kusokoneza pakugwiritsa ntchito ma frequency otsika. Phokoso la 1/f ndi phokoso la broadband makamaka limachokera ku phokoso la voteji la operational amplifier mkati mwa photodetector. Pali magwero ena ambiri a phokoso omwe amakhudza phokoso la photodetectors, monga phokoso lamagetsi la operational amplifier, phokoso lamagetsi, ndi phokoso la kutentha kwa netiweki yotsutsa pakuwonjezeka kwa ma operational amplifier circuits.

3. Phokoso la mphamvu ndi mphamvu yamagetsi ya amplifier yogwira ntchito: Mphamvu ya mphamvu ndi mphamvu yamagetsi yamagetsi ikuwonetsedwa pachithunzi chotsatirachi:

Mu ma circuits operational amplifier, phokoso lamagetsi limagawidwa m'magulu awiri: phokoso lamagetsi lamagetsi la in-phase ndi phokoso lamagetsi la inverting. Phokoso lamagetsi la in-phase i+ limadutsa mu resistance yamkati ya gwero la Rs, ndikupanga phokoso lamagetsi lofanana u1= i+*Rs. I- Phokoso lamagetsi la inverting limadutsa mu resistor yofanana ya gain R kuti lipange phokoso lamagetsi lofanana u2= I-* R. Chifukwa chake, pamene RS yamagetsi ili yayikulu, phokoso lamagetsi losinthidwa kuchokera ku phokoso lamagetsi nalonso ndi lalikulu kwambiri. Chifukwa chake, kuti liwongolere phokoso, phokoso lamagetsi (kuphatikiza kukana kwamkati) ndilofunikira kwambiri pakukonza. Kuchuluka kwa phokoso lamagetsi sikusintha ndi kusintha kwa ma frequency. Chifukwa chake, pambuyo poti lakulitsidwa ndi dera, ilo, monga mphamvu yakuda ya photodiode, limapanga phokoso lowombera la photodetector.

4. Phokoso la kutentha kwa netiweki yotsutsa kuti pakhale phindu (chinthu chowonjezera mphamvu) cha dera lothandizira likhoza kuwerengedwa pogwiritsa ntchito njira iyi:

Mwa iwo:

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

T: Kutentha Kosatha (K)

R: Phokoso la kutentha la Resistance (ohms) limagwirizana ndi kutentha ndi mtengo wotsutsa, ndipo sipekitiramu yake ndi yathyathyathya. Zitha kuwoneka kuchokera ku fomula kuti mtengo wotsutsa wa gain resistance ukakhala waukulu, phokoso la kutentha limakhala lalikulu. Bandwidth ikakula, phokoso la kutentha lidzakhala lalikulunso. Chifukwa chake, kuti zitsimikizire kuti mtengo wotsutsa ndi mtengo wa bandwidth zikwaniritse zofunikira za gain ndi zofunikira za bandwidth, komanso pamapeto pake zimafunanso phokoso lotsika kapena chiŵerengero chapamwamba cha chizindikiro-mpaka-phokoso, kusankha ma resistor a gain kuyenera kuganiziridwa mosamala ndikuwunikidwa kutengera zofunikira zenizeni za polojekiti kuti zikwaniritse chiŵerengero choyenera cha chizindikiro-mpaka-phokoso cha dongosololi.

Chidule

Ukadaulo wowongolera phokoso umagwira ntchito yofunika kwambiri pakukweza magwiridwe antchito a zida zowunikira zithunzi ndi zida zamagetsi. Kulondola kwambiri kumatanthauza phokoso lochepa. Popeza ukadaulo umafuna kulondola kwambiri, zofunikira za phokoso, chiŵerengero cha chizindikiro ndi phokoso, ndi mphamvu yofanana ya phokoso ya zida zowunikira zithunzi zikukulirakulira.