Graduate Institute of Photonics and Optoelectronics ~National Taiwan University Topic Report S/N of EUV based OCT 2012.05.03 Speaker：Yen-Yin Li Adviser： Sheng-Lung Huang

Outline Power for EUV application CCD specific Numerical calculation Summary In the end , thank you for your attention.

Power for EUV application Laser source: 1064nm, 2mJ, 20kHz Average power: 40W (ideal Amp W/O SRS) CE from laser to EUV is 1% The EUV power at source is 400mW Average power: 40W (2mW/ per shot) EUV source: 400mW (20μW/ per shot) Collection optics: Effective focal length: 100mm Diameter: 76.2mm (3”) Hole diameter:30/16/9 mm (2” f=127/225/400mm) Collection efficiency modified by angular distribution (Cosθ)^5.84 Collection efficiency: 37.37/43.42/45.11 Vacuum transmission of 55cm traveling at 0.05 torr : 77.75% Transmission of Si/Zr filter: 80%

Power for EUV application (1)5R, 1BS(RT), (2)5R,2BS(RRTT) (3)3R,1BS(RT) The ideal power for the EUV application is Vacuum transmission of 100cm traveling at 0.0005 torr : 99.5% Si/Mo reflection: 60% Beam splitter: T=R=25% Power before enter the grating: Michelson type: 269.7μW Mirau type: 16.9μW; Due to pass through BS twice. Mirau-like type: 749.3μW

CCD specific - ANDOR Pixels:1024x256 Pixel size: 26x26 (μm) QE:40% @13.5nm Read noise: 4 e- @50kHz Dark current: 0.0005 e- Pixel well depth:500,000 Maximum full frame rate:10

CCD specific - Princeton Pixels:1340x100 Pixel size: 20x20 (μm) QE:42% @13.5nm Read noise: 2.5 e- @100kHz Dark current: 0.001 e- Pixel well depth:1,000,000

SNR equations In the end , thank you for your attention.

Numerical calculation: ANDOR 1024*100 Electron number can’t excess the well depth. Exposure time is just 60 ms. (100ms per frame) The SNR is limited by shot noise. SNR= 56.35 dB @ 55.78mW

Numerical calculation: Princeton 1340*100 Electron number can’t excess the well depth. Exposure time is just 150 ms. (??? per frame) The SNR is limited by shot noise now. SNR= 59.37 dB @ 55.78mW

Summary The SNR of EUV based OCT is usually limited by the shot noise due to can’t arise the exposure time to do the average. The SNR can arise after the Fourier transform. For the ideal case, SNR can be improved N/2 times where N is the CCD pixel number. In the end , thank you for your attention. Future work, I will discuss the collector shape and the spectrometer.

Thank you for your attention End In the end , thank you for your attention. Thank you for your attention

SNR: source variation In the end , thank you for your attention.

CCD selection 鎖相環（PLL: Phase-locked loops）是一種利用反饋（Feedback）控制原理實現的頻率及相位的同步技術，其作用是將電路輸出的時鐘與其外部的參考時鐘保持同步。當參考時鐘的頻率或相位發生改變時，鎖相環會檢測到這種變化，並且通過其內部的反饋系統來調節輸出頻率，直到兩者重新同步，這種同步又稱為「鎖相」（Phase-locked）。