Optical Delay Line Implementation and Performance Metrics mu Terahertz Time-Domain Spectroscopy Systems

Mizere yochedwa ya Optical (ODLs) Pezani njira yowongolera yowunikira pogwiritsa ntchito makina olondola a zigawo zowunikira. Njira ziwiri zazikulu zimagwiritsidwa ntchito:

1. Machitidwe Osamutsa Anthu Olunjika

Chinthu chowunikira chomwe chimayikidwa pa nsanja yosinthira pang'ono chimamasuliridwa molunjika pogwiritsa ntchito ma actuator olunjika monga manual linear stages, ma stepper motors, ma voice coil actuators, kapena ma piezoelectric-driven linear motors. Kusuntha kwa makina kumeneku kumasinthasintha mwachindunji kutalika kwa njira yowunikira, zomwe zimapangitsa kuti pakhale kuchedwa kwa nthawi yofanana. Njirayi imapindula ndi kudalirika kwakukulu, kugwiritsa ntchito bwino ndalama, komanso kusanja kwa sub-micron positioning resolution, zomwe zimapangitsa kuti ikhale yofala kwambiri m'machitidwe amalonda ndi ofufuza a terahertz (THz).

2. Makonzedwe a Rotary Mirror

Ma mota ozungulira othamanga kwambiri amayendetsa ma optics owunikira kuti apange kusintha kwa njira yowunikira yozungulira. Ngakhale kuti zimathandiza kuti kuchuluka kwa zitsanzo kukhale kowonjezereka kudzera mu kusintha kwa liwiro la angular, njira iyi ikuwonetsa kusintha kwachilengedwe pakutha kwa kuchedwa chifukwa cha zoletsa zowongolera komanso kusafanana kwa kuzungulira.

Magawo Ofunikira Ogwira Ntchito a Mizere Yochedwa Yowala

1. Kuchedwa kwa Nthawi

Potanthauzidwa ngati zenera la temporal lomwe lingathe kufikika kwambiri (Δt_max), gawoli limatsimikiza resolution ya spectral ya system (Δν ≈ 1/Δt_max) mu muyeso wa frequency-domain. Kuchedwa kwa range kumayendetsedwa kwambiri ndi mtunda woyenda wa makina a actuator (L_max) ndi mawonekedwe a optical, kutsata ubale:Δt_max = (2nL_max)/c komwe n ndi refractive index ya propagation medium ndi c liwiro la kuwala.

2. Kulondola Kochedwa

Podziwika ndi kuwonjezereka kwa delay komwe kungathetsedwe (δt_min) ndi temporal jitter, gawo ili limakhudza kwambiri nthawi-domain signal fidelity ndi system signal-to-noise ratio (SNR). Kulondola kumayendetsedwa ndi:

Chisankho cha malo a Actuator (<100 nm pa magawo olondola)

Sinthani kuchedwa kwa mayankho a dongosolo

Kuthamanga kwa makina ndi kutentha

3. Makhalidwe Otayika Omwe Amayikidwa

Pokhala ndi zigawo zonse ziwiri zotayika mosasunthika komanso kusinthasintha kwamphamvu pamlingo wochedwa, kutayika kwa kuyika kumaonekera motere:

Kutayika Konse Komwe Kulowetsedwa (IL_abs): Kuchepetsa kosasinthika kuchokera ku zigawo za kuwala (nthawi zambiri 1-3 dB ya ma ODL apamwamba)

Kutayika kwa Kuikapo Kosiyanasiyana (ΔIL): Kusinthasintha kwa mphamvu panthawi yojambula, makamaka chifukwa cha kuyenda kwa beam-off ndi kutayika komwe kumadalira polarization. ΔIL < 0.5 dB ndikofunikira kwambiri kuti pulse amplitude ikhale yofanana ndi THz.

Zotsatira za Mulingo wa Dongosolo

Mu mapangidwe a terahertz time-domain spectroscopy (THz-TDS), magwiridwe antchito a ODL amalamulira mwachindunji miyezo itatu yofunika kwambiri ya dongosolo:

Kusasinthika kwakanthawi (<100 fs yomwe ingatheke ndi magawo olondola)

Kuchuluka kwa ma spectral (>0.1 cm⁻¹ ndi ma stand a delay ranges otalikirapo)

Mitundu yosinthika (60-80 dB SNR kutengera kukhazikika kwa kutayika)

Machitidwe apamwamba tsopano akuphatikiza kutsimikizika kwa malo otsekedwa pakati pa ma closed-loop interferometric ndi ma adaptive optics kuti athandizire kusiyana kwa kuwala, zomwe zimapangitsa kulondola kwa kuchedwa kukhala pansi pa 10 fs RMS m'makina apamwamba kwambiri. Kusankha pakati pa ma linear ndi ma rotary configurations pamapeto pake kumadalira zofunikira za pulogalamu kuti iwonetse liwiro la scan poyerekeza ndi resolution, ndi mayankho osakanikirana omwe akubwera kuti agwiritse ntchito zithunzi za THz mwachangu kwambiri.