作者luben (鲁蛇中的鲁蛇)
看板Physics
标题[问题]几个光学问题
时间Mon Apr 24 00:01:03 2017
1.A commercial pulsed Titanium-Sapphire laser could produce a pulse train with
80MHz repetition rate of 300 femtoseconds (FWHM) Gaussian pulses around 800 nm with
average power of 2.5 Watt.
If another laser is producing a continuous wave (CW) with the same average
power of 2.5 Watt and at 800 nm wavelength as this pulsed laser,
Question: For two-photon excitation experiments, which laser (pulsed or CW one) is the
better choice, why?
感觉是跟photons的数量有关,算起来pulsed的photons较高
请问是这样吗?
依常理判断,通常是CW较佳才对(cost比pulsed低....)
2.When benzene molecules are dissolved in ethanol at 25ºC, its fluorescence
lifetime is 31 ns and the fluorescence quantum yield is 0.04.
Question:To measure the fluorescence lifetime of 31ns, what would be the proper
modulation frequency (Hz) range, if the frequency-domain time-resolved fluorescence spectroscopy
is used?
感觉没有modulation(M)跟 phase-shift(Phi) 无法计算 range
是我用错公式吗?
请大家指导,谢谢
--
※ 发信站: 批踢踢实业坊(ptt.cc), 来自: 220.136.32.132
※ 文章网址: https://webptt.com/cn.aspx?n=bbs/Physics/M.1492963265.A.87A.html
1F：→ hank780420: 第一个刚好最近听过相关的talk multi-photon需要非常 04/24 00:03
2F：→ hank780420: 高的光子通量才有机会发生 连续跟脉冲就算功率差不多 04/24 00:03
3F：→ hank780420: 脉冲那一瞬间的光子量远远超过一般连续的雷射 04/24 00:04
4F：推 youzi1114: 其实要比的就是瞬间功率，连续光瞬间功率等於平均功率 04/24 23:32
5F：→ youzi1114: ，脉冲则是平均功率除重复率(变能量)再除脉宽 04/24 23:32
6F：→ luben: 请问重复率(变能量)有办法计算吗? 不然题目似乎没有给.. 04/24 23:49
7F：→ ftsywind: 重覆率80MHz题目有给 04/25 12:57
8F：→ luben: 谢谢指导 想问第二题是否没有phi角无法计算呢? 04/25 21:26
9F：→ shengwey: 31ns~5MHz linewidth. Whatever modulation scheme it' 04/26 23:39
10F：→ shengwey: s referring to should have a depth about 5MHz. 04/26 23:39