Bright-field (BF)and dark-field (DF)are the most commonly used examination modes. BF OBJECTIVE- OR.IECT CONDENSER- 一APERTURE- ANNULAR STOP-IRIS CENTRAL STOP Figure 1.28 (a)Bright-field illumination;and (b)dark-field illumination in transmitted mode.Shaded areas indicate where the light is blocked. Figures from Leng,pages 26,27. 10: 6
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50μm Optical bright field and dark-field metallographic images of a Zircaloy- 4 cladding oxidised in air at 850C(see text section D for signification of regions 1,2,3 and 4) from Nuclear Engineering and Design,Volume 239,Issue 2,February 2009,Pages 244-253
7 Optical bright field and dark-field metallographic images of a Zircaloy- 4 cladding oxidised in air at 850oC (see text section D for signification of regions 1, 2, 3 and 4) from Nuclear Engineering and Design, Volume 239, Issue 2, February 2009, Pages 244–253
相位衬度显微术 a) Reference wave b) Amplitude Reduced object amplitude Phase c) Retarded object phase Figure 7-2 Effects of amplitude and phase objects on the waveform of light.(a)Reference ray with characteristic amplitude,wavelength,and phase.(b)A pure amplitude object absorbs energy and reduces the amplitude,but does not alter the phase,of an emergent ray.(c)A pure phase object alters velocity and shifts the phase,but not the amplitude,of an emergent ray. 8
相位衬度显微术 8
Phase Contrast Imaging of Transparent Thin Specimens (a) (b) (c) △1 A2 Nucleus (Thickest Portion) Adherent Cell Cell Edge (Thin) Incident Coverslip Transmitted Light lllumination一 Figure 2 如何将相位差转变为亮度差？ 9
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P wave S wave Incident beam,λ D wave 11 Ad<<X 20 △ (b) B Vectors 2π6 4π△d S Wave λ P Wave D Wave 10
10 B A d S P S P D Incident beam, 𝜑 = 2𝜋𝛿𝜆 = 4 𝜋 Δ 𝑑 𝜆 d<<