Design of a static spectropolarim imeter Bogdan Vasilescu - - PowerPoint PPT Presentation
Design of a static spectropolarim imeter Bogdan Vasilescu Supervisor: Prof. Jrme Loicq The objective To improve the technique for the massive stars observation Massive stars: o Masse > 10 o Luminosity: 10 5 10 6
Bogdan Vasilescu Supervisor: Prof. Jérôme Loicq
➢Massive stars:
10−7 − 10−4𝑁⨀𝑧𝑠−1
(∼ ℎ𝐻 − 𝑙𝐻)
eso.org R136a1 ∼ 256𝑁⨀
𝑇𝑗𝑜 = 𝐽𝑗𝑜 𝑅𝑗𝑜 𝑉𝑗𝑜 𝑊
𝑗𝑜
𝑇𝑝𝑣𝑢 = 𝐽𝑝𝑣𝑢 𝑅𝑝𝑣𝑢 𝑉𝑝𝑣𝑢 𝑊
𝑝𝑣𝑢
= 𝑁𝑇𝑗𝑜 𝑁: the Mueller matrix
𝑦: spatial modulation (beam splitting) : LARGE VOLUME 𝑢: temporal modulation (rotation; piezo-elastic modulation) : FAILURE, HIGH VOLTAGE
Retarding plate (modulator) Φ Polarizer (analyzer) 𝜄 𝐽𝑝𝑣𝑢 = 𝑁00(𝐽𝑗𝑜 + ℎ1(𝑦; 𝑢) ∙ 𝑅𝑗𝑜 + ℎ2(𝑦; 𝑢) ∙ 𝑉𝑗𝑜 + ℎ3(𝑦; 𝑢) ∙ 𝑊
𝑗𝑜)
𝜊 2𝜊 𝑁𝐺2 modulator Fast axis y z x O
Incoming ray Polarizer 𝜄 Spectrometer
𝑇 = [1, 0.4, 0.3, 0.5]𝑈
𝐽𝑝𝑣𝑢=
1 2(𝐽 + 𝑅 ∙ 𝑛 𝑧, λ + 𝑉 ∙ 𝑜 𝑧, λ + 𝑊 ∙ 𝑞 𝑧, λ )
m 𝑧, λ =cos 2𝜄 cos(∆𝜒2) n 𝑧, λ =sin 2𝜄 cos(∆𝜒1)+cos 2𝜄 sin(∆𝜒1) sin(∆𝜒2) p 𝑧, λ =cos 2𝜄 cos ∆𝜒1 − sin 2𝜄 sin (∆𝜒1)
𝐽𝑝𝑣𝑢 = 𝑁00(𝐽𝑗𝑜 + ℎ1(𝑦; 𝑢) ∙ 𝑅𝑗𝑜 + ℎ2(𝑦; 𝑢) ∙ 𝑉𝑗𝑜 + ℎ3(𝑦; 𝑢) ∙ 𝑊
𝑗𝑜)
𝑇 = [1, 0.4, 0.3, 0.5]𝑈
I. Ideal conditions II. The presence of noise Functioning in:
❑Behaviour in ideal conditions: unicity of the solution
𝜊 2𝜊 𝑁𝐺2 modulator Fast axis y z x O
𝑇1
Polarizer 𝜄
𝑇2 𝑇
❑Behaviour in simulated real conditions: SNR dependent ➢Optimization of the analyzer (minimization of the 𝜓2 distribution)
❑ Efficiency of the modulation (after Toro Iniesta, 2003)
❑Behaviour in simulated real conditions: SNR dependent ➢Relative error & standard deviation (𝜄 = 109°, 𝑇 = [1, 0.4, 0.3, 0.5]𝑈)
❑Behaviour in simulated real conditions: oblique rays (𝜄 = 90°, 𝑇 = [1, 0.4, 0.3, 0.5]𝑈)