1. 光學元件精密製造與檢測 Precision Manufacturing & Inspection of Optical Components
--- Ch.12 組件品質檢測
Speaker: Bo-Wen Xiao (蕭博文)
Advisor: Prof. Yi-Pai Huang (黃乙白教授)
Prof. Chung-Hao Tien(田仲豪教授)
Institute of Electro-Optical Engineering,
National Chiao Tung University, Hsinchu, Taiwan
Apr

2. Outline Effective focal length (EFL) Diffusion characteristics
- Direct measurement method
- Magnification method
Diffusion characteristics
- Bidirectional scattering distribution function (BSDF)
- Scatterometer
Polarization
- Polarization & Polarizer
- Birefringence crystal & Phase retarder
- Inspection of polarizer
Conclusions

3. If n=n'', N and N' coincide with P,P'
Cardinal point n n'
n''
F, F' : front and rear focal points
P, P' : front and rear principal points
V, V' : front and rear surface vertices
N, N' : front and rear nodal points
If n=n'', N and N' coincide with P,P'

4. Direct Measurement Method
nodal slide (光具座) ：
measuring the distance between N’ and F’ directly
EFL

5. Magnification Method More easy and convenient to measure.
focimeter (焦距儀) ：
measuring the EFL by calculating magnification
EFL
More easy and convenient to measure.
Suitable to utilize in production line. 

6. Outline Effective focal length (EFL) Diffusion characteristics
- Direct measurement method
- Magnification method
Diffusion characteristics
- Bidirectional scattering distribution function (BSDF)
- Scatterometer
Polarization
- Polarization & Polarizer
- Birefringence crystal & Phase retarder
- Inspection of polarizer
Conclusions

7. Diffusion Characteristics
Refraction
Reflection
Absorption
Diffuse/Scattering
Volume scattering
Material
Surface
Different !!
Different !!
Diffusion characteristic of diffuser :
Diffuser
- refractive index of material
- dimension and geometry of particle

8. Description of Diffusion Characteristic
Bidirectional scattering distribution function (BSDF)
- Bidirectional transmission scattering distribution function (BTDF)
- Bidirectional reflection scattering distribution function (BRDF)
- Bidirectional volume scattering distribution function (BVDF)

9. Reflection-type could be a good choice.
Scatterometer
Degrees of mechanical freedom :
- 3 translational degrees of freedom
 adjust position
- 3 rotational degrees of freedom
adjust azimuth angle θ
　 zenith angle Φ
Dynamic range :
>60dB
Design of self-component :
- Transmission-type
 eliminate off-axis aberration
(number of lens ↑)
cause noise & ghost path
(scattering and volume scattering)
Reflection-type could be a good choice.
- Reflection-type
no volume scattering
no chromatic aberration
(number of lens ↓)

10. Outline Effective focal length (EFL) Diffusion characteristics
- Direct measurement method
- Magnification method
Diffusion characteristics
- Bidirectional scattering distribution function (BSDF)
- Scatterometer
Polarization
- Polarization & Polarizer
- Birefringence crystal & Phase retarder
- Inspection of polarizer
Conclusions

11. Circular polarization Elliptical polarization
Linear polarization
Circular polarization
Elliptical polarization
Linear polarization
Circular polarization
Elliptical polarization

12. Polarizer Absorptive polarizer (Dichroic polarizer) - Wire-grid (金屬網狀)
Larger volume , higher cost
- Sheet (片狀)
J-sheet polarizer (by Edwin H. Land ,1928)
nitrocellulose(硝棉) polymer + iodoquinine sulfate (硫酸鹽碘化物)
EM field
H-sheet polarizer (by Edwin H. Land ,1938)
Easier to fabricate
polyvinvl alcohol (PVA, 聚乙烯醇) + iodine (碘)
Influence by humidity and heat (high vapor pressure of iodone)
external force
K-sheet polarizer
Higher stability and polarization efficiency
heat & catalyst  evaporate water

13. Polarizer (ii) Reflective polarizer s+p - Brewster plate
Brewster angle s
- Polarization beam splitter (PBS)
MacNeille polarizing prism p
MacNeille 麥尼利 s

14. Birefringence Crystal & Phase Retarder
Phase difference
Polarization conversion system (PCS)
Phase retarder
- Half-wave plate
X-LP  Y- LP
- Quarter-wave plate
LP  Circular Polarization

15. Inspection of Polarizer
Direction of polarization
find out θ
Extinction ratio
(消除比)
∞ (ideal)
> (real)
Polarization efficiency
(偏極效率)
1 (ideal)
> 99%(real)

16. Outline Effective focal length (EFL) Diffusion characteristics
- Direct measurement method
- Magnification method
Diffusion characteristics
- Bidirectional scattering distribution function (BSDF)
- Scatterometer
Polarization
- Polarization & Polarizer
- Birefringence crystal & Phase retarder
- Inspection of polarizer
Conclusions

17. Conclusions Effective focal length Diffusion characteristics
- EFL can be measured by two methods.
(Direct measurement method & Magnification method)
Diffusion characteristics
- Diffusion characteristics can be described by BSDF.
(BTDF, BRDF, BVDF)
- BSDF can be measured by scatterometer.
Polarization
- Polarizer & phase retarder can be utilized in LCD system.

18. Thank you for your kind attention !!

19. Reticle

20. PBS
Wollaston prism
Commercial prisms are available with divergence angles from 15° to about 45°