Qhov sib txawv tseem ceeb ntawm uniaxial thiab biaxial siv lead ua yog tias uniaxial siv lead ua muaj ib qho optic axis whereas biaxial crystals muaj ob optic axes.
Lub optic axis ntawm ib lub siv lead ua yog cov kev taw qhia uas lub teeb propagates los ntawm cov siv lead ua yam tsis muaj ob lub refraction. Txhua lub teeb nthwv dej uas sib npaug rau qhov axis no tsis dhau ob lub refraction. Hauv lwm lo lus, lub teeb lub teeb hla mus rau hauv qhov kev taw qhia nrog qhov nrawm uas tsis nyob ntawm qhov polarisation.
Uniaxial Crystals yog dab tsi?
Ib lub uniaxial siv lead ua yog ib qho khoom siv kho qhov muag uas muaj ib qho axis optic. Nyob rau hauv lwm yam lus, ib tug uniaxial siv lead ua muaj ib tug siv lead ua axis txawv los ntawm lwm yam ob crystallographic axes. Ex: na=nb≠ nc Tus axis tshwj xeeb no hu ua axis txawv tshaj plaw. Thaum lub teeb ci hla dhau los ntawm ib qho uniaxial siv lead ua, lub teeb ci ntsa iab tau faib ua ob feem xws li cov kab hluav taws xob zoo tib yam thiab cov kab hluav taws xob txawv tshaj plaw. Cov kab hluav taws xob zoo tib yam (o-ray) dhau los ntawm cov siv lead ua yam tsis muaj qhov sib txawv. Cov kab hluav taws xob txawv tshaj plaw (e-ray) sib txawv ntawm huab cua-crystal interface.
Muaj ob hom uniaxial siv lead ua lub npe hu ua tsis zoo uniaxial siv lead ua thiab zoo uniaxial siv lead ua. Yog hais tias lub refraction Performance index ntawm o-ray (no) loj dua li ntawm e-ray (ne), ces nws yog ib qho tsis zoo uniaxial siv lead ua. Tab sis yog tias qhov ntsuas ntsuas ntawm e-ray (ne) yog me dua li ntawm e-ray, ces nws yog ib qho zoo uniaxial siv lead ua.(Refractive Performance index yog qhov piv ntawm qhov nrawm ntawm lub teeb hauv lub tshuab nqus tsev rau nws qhov nrawm hauv cov siv lead ua). Piv txwv ntawm qhov tsis zoo uniaxial crystals muaj xws li calcite (CaCO3), ruby (Al2O3), thiab lwm yam. Piv txwv ntawm zoo uniaxial siv lead ua muaj xws li quartz (SiO2), sellaite (MgF2), rutile (TiO2), thiab lwm yam.
Dab tsi yog Biaxial Crystals?
Ib lub ntsej muag biaxial yog ib qho khoom siv kho qhov muag uas muaj ob lub axes optic. Thaum lub teeb ci hla dhau los ntawm biaxial siv lead ua, lub teeb beam faib ua ob feem, ua ob feem yog qhov txawv tshaj plaw (ob lub e-rays). Cov nthwv dej no muaj kev taw qhia sib txawv thiab sib txawv ceev. Cov qauv crystalline xws li orthorhombic, monoclinic, lossis triclinic yog cov tshuab siv lead ua biaxial.
Cov Kev Ntsuas Refractive rau Biaxial Crystal yog raws li hauv qab no:
- Qhov tsawg tshaj plaws qhov ntsuas qhov taw qhia yog α (cov kev coj ua yog X)
- Qhov nruab nrab qhov ntsuas qhov ntsuas nruab nrab yog β (cov kev coj ua yog Y)
- Qhov loj tshaj plaws refractive index yog γ (cov kev taw qhia sib xws yog Z)
Daim duab 01: Qhov Ntsuas ntawm Biaxial Crystal. (Indicatrix yog ib qho kev xav ellipsoidal nto uas nws cov axes sawv cev rau cov refractive indices ntawm cov siv lead ua rau lub teeb raws li cov lus qhia sib txawv txog cov siv lead ua axes)
Txawm li cas los xij, cov lus qhia kho qhov muag thiab cov ntsuas ntsuas qhov ntsuas tsis sib txawv ntawm cov axes crystallographic ntawm qhov xwm txheej ntawm cov siv lead ua.
- Orthorhombic siv lead ua qhov system - cov lus qhia kho qhov muag sib haum rau cov axes crystallographic. Piv txwv li: X, Y lossis Z cov lus qhia (α, β thiab γ refractive indices) tuaj yeem sib npaug rau ib qho ntawm cov axes crystallographic (a, b lossis c).
- Monoclinic siv lead ua qhov system - ib qho ntawm X, Y thiab Z cov lus qhia (α, β thiab γ refractive indices) yog sib npaug rau b crystallographic axis thaum lwm ob txoj kev coj tsis sib xws rau cov kev taw qhia crystallographic.
- Triclinic siv lead ua qhov system - tsis muaj cov lus qhia kho qhov muag coincide nrog crystallographic axes.
Muaj ob hom biaxial crystals xws li, tsis zoo biaxial siv lead ua thiab zoo biaxial crystals. Tsis zoo biaxial crystals muaj lawv β ze rau γ dua li α. Cov muaju zoo biaxial muaj lawv β ze rau α dua li γ.
Qhov txawv ntawm Uniaxial thiab Biaxial Crystals yog dab tsi?
Uniaxial vs Biaxial Crystals |
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| Ib lub uniaxial siv lead ua yog ib qho khoom siv kho qhov muag uas muaj ib qho kev kho qhov muag. | Ib tug siv lead ua biaxial yog ib qho khoom siv kho qhov muag uas muaj ob lub qhov muag pom. |
| Neegative Form | |
| Ib qho tsis zoo uniaxial siv lead ua muaj qhov ntsuas qhov ntsuas ntawm o-ray (no) loj dua li ntawm e-ray (ne). | Ib tug tsis zoo biaxial siv lead ua muaj nws β ze rau γ dua li α. |
| Thaum ib lub teeb ci dhau los ntawm cov siv lead ua uniaxial, lub teeb pom kev sib cais ua ob lub rays hu ua lub teeb zoo tib yam (o-ray) thiab cov hluav taws xob txawv txawv (E-ray). | Thaum ib lub teeb ci dhau los ntawm cov siv lead ua biaxial, lub teeb pom kev sib cais ua ob lub rays uas yog ob qho tib si yog cov kab hluav taws xob txawv txawv (e-rays). |
| Daim Ntawv Pom Zoo | |
| A zoo uniaxial siv lead ua muaj qhov taw qhia ntawm e-ray (ne) yog me dua li ntawm e-ray (ne). | Ib qho zoo biaxial siv lead ua muaj nws β ze rau α dua li γ. |
| Examples | |
| Quartz, calcite, rutile, thiab lwm yam. | Tag nrho cov monoclinic, triclinic ib orthorhombic siv lead ua tshuab |
Summary – Uniaxial vs Biaxial Crystals
Crystals yog cov khoom uas nws cov atoms tau teem rau hauv kev txiav txim zoo. Tsis tas li ntawd, ob lub pob zeb no muaj nyob rau hauv ob hom li uniaxial crystals thiab biaxial crystals, raws li tus naj npawb ntawm optic axes tam sim no hauv cov qauv siv lead ua. Qhov txawv ntawm uniaxial thiab biaxial crystals yog tias uniaxial siv lead ua muaj ib qho optic axis whereas biaxial crystals muaj ob optic axes.
