f*******t
发帖数: 30 | 1 Job description: Laser Application Engineer/Scientist
Candidates will be responsible for investigating the feasibility of using
lasers for laser material processing and should understand laser-material
interactions and be capable of optimizing processing parameters (including
laser wavelength, power, pulse energy, pulse width, etc). Develop new laser
processes for different industries such as semiconductor, electronics, and
medical. Improve our understanding of laser/material interaction throug |
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m******i
发帖数: 834 | 2 据Nanowerk报道， Large-scale and high-density semiconductor arrays with one-
dimensional ("1D" - where one dimension of the structure is nanoscale)
nanostructures have been extensively studied for their potential application
in future electrooptical devices. Among them, zinc oxide (ZnO) is
considered to be very attractive for high-efficiency short-wavelength
optoelectronic nanodevices because of its large exciton binding energy of 60
meV and high mechanical and thermal stabilities. ZnO nanorod/ nano |
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s**l
发帖数: 869 | 3 谢谢
看到的UV光源大都从200nm起
请推荐合适的仪器 |
|
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s**l
发帖数: 869 | 5 x-ray光源波长能到100nm左右吗？
我看到的大都是几个埃的 |
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t***s
发帖数: 163 | 6 you may think about wavelength of laser for Raman. |
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f******n
发帖数: 72 | 7
Yes！
Definitely, graphene and CNT have wide applications.
In my field: passively mode locking fiber lasers,several companies have used
CNT to mode lock fiber lasers and generate high power fs pulses.
CNT based saturable absorber has become commercialized.
Moreover,similiar to CNT, graphene could also be used as ultra-fast
universial saturable absorber which could mode lock lasers at any wavelength.
If you feel interested, you could visit wiki website of graphene:
http://en.wikipedia.org/wiki/Gr |
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f******n
发帖数: 72 | 8
used
wavelength.
http://www.natureasia.com/asia-materials/highlight.php?id=594
石墨烯锁模被Nature Asia亮点了！
NPG Asia Materials research highlight | doi:
Published online 21 December 2009
Graphene: Mode-locked lasers
Fig. 1: A graphene–polymer composite film (white) can be used as a laser
mode locker. The laser schematic is shown in the background, and an optical
fiber for laser output is shown on the left.
Although graphene potentially has many applications, reports on exploiting
its optical propertie |
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b******n
发帖数: 80 | 9 Sorry I can not type it in chinese since I am in lab right now.
There are lots of papers concerning the hybrid structure in localized
surface plasmon resonance (LSPR). I found that they are 2 catalogs. One is
photo quenching, the other is PL enhanced.
I have asked a expert that whether the PL of semiconductor can be enhanced
by LSPR. He said it is definitely not because the excited electron-hole pair
will transfer to metal rapidly resulting in quenching.
In my opinion, that is just one factor. I... 阅读全帖 |
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发帖数: 1 | 12 大家好，
我们研究组最近有一个博后职位空缺。有意者可以直接申请。
Research Fellow in Nanophotonic Devices (Job No. 0040356)
A Research Fellow in Nanophotonic Devices position under the supervision of
Professor Kenneth Crozier is available in the Department of Electrical and
Electronic Engineering, at the University of Melbourne. Further information
on Professor Crozier's research group can be found at: http://kcrozier.eng.unimelb.edu.au/
The position involves the experimental demonstration of long wavelength
infrared photodet... 阅读全帖 |
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b****y
发帖数: 44 | 13 Although the NA does not change, in water the lamda of the wavelength is
varying so that the diameter should change? |
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f*******t
发帖数: 30 | 14 Job description: Laser Application Engineer/Scientist
Candidates will be responsible for investigating the feasibility of using
lasers for laser material processing and should understand laser-material
interactions and be capable of optimizing processing parameters (including
laser wavelength, power, pulse energy, pulse width, etc). Develop new laser
processes for different industries such as semiconductor, electronics, and
medical. Improve our understanding of laser/material interaction through |
|
w*****s
发帖数: 4116 | 15 Based on what I know, the spectral (wavelength) is the same, or almost same.
Just the pulse width in time (or space) changed. Your measured spectral
before fiber is strange. It has two peaks. Maybe they have interference. So
you have strange peaks after fiber.
Please double check the auto-correlation. In most cases you will get a
bigger FWHM.
Did the fiber have integrated filter at terminal?
What are the properties of second and third phase speed for this fiber?
Contact with the manufacture to g |
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X******U
发帖数: 137 | 16 1) light is also electromagnetic wave. Maxwell equations are wavelength
invariant. If you treat metal as perfect conductance, than according to the
boundary conditions, light with parallel polarization will not pass. This is
similar to the waveguide problem, if you man recall.
2) Where did you find this statement? The word cross section itself implies
that it is calculated by treating light as streams of photons. I have no
idea how to connect these two theories. Also, as someone has pointed out, |
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h*********6
发帖数: 2469 | 17 1. The pitch of the metal grating must be smaller than the wavelength of the
light, otherwise you would get non-zero diffraction orders. |
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h*********6
发帖数: 2469 | 18 I believe so. I remember there is a relation that connects the real part of
the permitivity function to its imaginary part (both are functions of
wavelength). |
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x******i
发帖数: 3022 | 19 I think it's probably some oscillating component generating high frequency
hence short wavelength water waves with high amplitude --- the waves break
and become droplets. |
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h*********6
发帖数: 103 | 20 〉Otherwise, the wavefront will move as a free particle.
I know this. Actually Feynman said, in his book "QED", that a big space (
here a wide slit) would make other wave paths cancel out so that the light
behaves like a particle.
However, what I am wondering here is:
Why did Feynman calculate diffraction pattern using the slit width, when the
slit width is comparable with the particle wavelength?
diffraction. |
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p***e
发帖数: 402 | 21 http://news.illinois.edu/NEWS/06/0608uaser.html
倒数第三段.
Nevertheless, uasers may be useful. With their longer wavelengths and more
convenient frequencies, uasers
could prove useful for modeling and studying laser dynamics. They could also
serve as highly sensitive
scientific tools for measuring the elastic properties and phase changes of
modern materials, such as thin films
or high-temperature superconductors.
“Uasers can produce an ultrasonic version of acoustical feedback – an
ultrasonic howl s |
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i*o
发帖数: 202 | 22 请教一下有没有人有以下各种dye 的2photon absorption and emission spectra 的资料
PE
PE Texas Red
PE cy7
PerCp-Cy5.5
APC
APC-cy7
Alexa Fluo 430
任何信息都可以 谢谢！！ |
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c**m
发帖数: 1632 | 23 Acoustic phonons close to the long wavelength limit. Rough estimation gives
2*pi*Vs/kB*T and that's why they talked about breather mode of the HTc
ceramics. From my perspective, not so much physics there. The mechanism of
HTc superconductivity is the "coulomb-repulsion induced electron coherent
state" though the exact model is not available. "Phonon assisted pairing
mechanism" works for low temperature superconductors and it could not
explain the phase transition in chemical stoichiometry. |
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h*********6
发帖数: 2469 | 24 什么是波分复用？Wavelength division multiplexing?
波分复用。
.33-1.66微米的，和1.66-2微米的三束光，这个可以叫波分复用吗？
受光面积可以很大，请问光子晶体的受光面积可以和光栅一样大吗？觉得光栅用于波分
复用时在转换效率上接近100%，(因为光栅只根据波长改变其传播方向，而不过滤光的
能量），请问光子晶体是在某个面积上是过滤某一波长的光，还是像光栅一样只是改变
其传播方向？ |
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c*****d
发帖数: 656 | 25 The process contains photon->electron->photon, which means it uses the
wavelength of electron instead of photon. Therefore ppl said SPP break the
diffraction limit of photon. |
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p***y
发帖数: 239 | 26 His publication on Science.
Broadband Ground-Plane Cloak
Author(s): Liu, R (Liu, R.)2; Ji, C (Ji, C.)3; Mock, JJ (Mock, J. J.)2; Chin
, JY (Chin, J. Y.)1; Cui, TJ (Cui, T. J.)1; Smith, DR (Smith, D. R.)2
Source: SCIENCE Volume: 323 Issue: 5912 Pages: 366-369 DOI: 10.1126/
science.1166949 Published: JAN 16 2009
Abstract: The possibility of cloaking an object from detection by
electromagnetic waves has recently become a topic of considerable interest.
The design of a cloak uses transforma... 阅读全帖 |
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m*d
发帖数: 103 | 27 by space wrapping. Is it possible a photon run a circle with a mass (such as
black holes) at the center with a proper radius?
what if it's not integer times of the photon wavelength? |
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S*********k
发帖数: 507 | 28 From today's NY Times:
Tingye Li （厉鼎毅）, Instrumental in the Laser’s Development, Dies at 81
Tingye Li, an electrical engineer whose calculations in the early 1960s
helped guide the development of the laser and propel the dizzying increase
in the speed of fiber-optic communication, died on Dec. 27 in Snowbird, Utah
. He was 81.
Family photo
Some of the work done by Dr. Tingye Li and his colleagues at Bell Labs laid
the groundwork for today’s broadband.
The cause was a heart attack while he was on... 阅读全帖 |
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t*******e
发帖数: 216 | 29 作为色彩成像的物理本质，是不同的物体，对于自然光不同波长（频率）的吸收率不一
样，反射率也不一样；并且这个吸收率反射率在弱光情况下可以近似为常数，但是在强
光下，它们就随光强变化而变，这个也与物体的组成成分有关，万物皆不同。
我们知道自然光是什么色彩都有的，因此，你在特定光强下看到物体的色彩，是由物体
在吸收了特定自然光波长，并且反射了某些自然光波长所看的光波长综合效果，这就是
光色彩合成的原理。
以上是物理上的分析，但是如果设计到摄影，这个问题就变得有些主观了。因为每个人
的眼睛不同，在欣赏景色的时候心情不同，观察到的色彩也不同，很多人都会有种感觉
当心情极端不好的时候，世界都是灰色的。所以，你所说的逼真，一定要加个引号，这
取决与你希望你的作品表现什么样的心境，这就是所谓象由心生。
再说一下LCD，任何的发光电子元件，组成色彩的方式都是通过直接模仿物体反射到你
眼睛中的被频率选择吸收过的自然光，其方法就是用三原色来配比，由于数字化的位数
越来越高，因此可以配比的颜色层次就逐渐使得眼睛无法区分电子光学成像与实际自然
光成像的区别了，那么这就取决于你的LCD/LED/Plasma的显示... 阅读全帖 |
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k*****a
发帖数: 13 | 30
This is not weak at all, but
What kind of IR? Give me a wavelength. |
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l**n
发帖数: 67 | 31 Yesterday, i was talking with some people and they
mentioned that recently some kind of new star
has been observed. It seems to me that they call
it brown dwarf(my english is poor and very likely
misheard what they said:(() which are very very
infrared. The wavelength of light emitted is about
10,000A.(not because of the redshift but simply
because those stars are very cold) I wonder with
more and more colder star being found, do we still
need dark matter(non-baryonic matter)? |
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s***e
发帖数: 911 | 32 Superluminal terahertz pulses
Klaas Wynne and Dino A. Jaroszynski
In femtosecond terahertz-pulse (T-ray) imaging of metal structures with
dimensions of the order of the wavelength, it is observed that the T rays
propagate faster than the vacuum speed of light. In the case of apertures
this can be understood as a waveguide effect in which superluminal velocities
are expected close to the cutoff frequency. However, the effect is also
observed close to knife edges and in propagation past thin metal |
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s**e
发帖数: 103 | 33
but he has emphsized it is not single wavelength. Maybe it does not have
a well defined central frequency. |
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f*x
发帖数: 7 | 34 Photonic crystals are three-dimensional dielectric structures with lattice
parameter on the order of the wavelength of light. This has a similar
influece on the propagation of light as atomic crystals have on electrons.
Thus, the dispersion relation of light can be desribed with band structures
in a Brillouin zone in recipocal space. Photonic crystals are being pursued
to obtain a range of forbidden frequncies--a photonic bandgap - in the
optical range. This has important quantum optical consequ |
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s********k
发帖数: 107 | 35
This has some prerequsite: the length of wire should be less than half of
wavelength of light. Otherwise, we must use Maxwell Equations to solve the
this problem.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~This is totally wrong for
conductors(solid). Use Fermi-Dirac distribution, When T=0, the avrage energy
is 0.6E_{F}. And the velocity is about 0.1c for the general conductors. |
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c**r
发帖数: 2019 | 36 general sweeps, i mean the sweeps used in analytical instruments, ranges from
1000m (LW radio frequency) to 10^(-10)m (X-ray), in wavelength. The
application is mostly for material analysis and determination.
E.g., if we have a piece of organic mixture and want to know its components,
we may just sweep IR (infra-red) though/on it, by observing the absorbance
peaks on the transmission/reflection spectrograph (x-axis is the frequency,
y-axis is the absorbed intensity), we would know the differrent |
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p*****m
发帖数: 7030 | 37 这个挺有趣哈 我这么想 植物先进化出了各种各样的色素来吸收太阳光谱里面的很小一
段 之后才会有动物据此进化出识别这些颜色的视觉（比如看见绿色和泥土色石头色的
区别 因为要吃东西 blabla） 其他的动物色觉是不是也可以类推成co-evolution的作
用 比如说你看夜行动物像猫头鹰因为看不到食物的颜色压根就没有颜色觉
至于植物为什么只选择了那么窄的一段光谱来形成色素 比如说叶绿素 基本所有的光合
作用生物都有 而且基本都是吸收红/蓝光从而呈现绿色 这个不知道有没有人知道。。
也许压根就是随机选择了Mg做色素核心的结果？当然也有可能有进化原因
刚wiki来这一段挺有趣得：
Why green and not black
Black plants can absorb more radiation, and yet most plants are green
It is as yet unclear exactly why plants (or rather, their light absorbing
molecule, chlorophyll) have mostly evolve... 阅读全帖 |
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m***f
发帖数: 1622 | 38 co-evolution是个新颖的观点
我倒是想从蛋白质、DNA等生物大分子的活性作为限制条件出发来看这个问题，
把温度看成调节手段，从而能够得出植物必须在‘绿色’光范畴才能发挥最佳活性。而
绿色周围的红或紫色光等范畴是其边界值，超出这个边界植物或凋亡、或枯萎。
可以预测，如果蛋白质等生物大分子最佳生活温度如果是100 度，而非20度
那么‘绿色’光波长就不是现在的500左右，而可能是2000 nm
动物照样受生物大分子活性的限制，所以其最佳生存光波范围也是有色光范畴
因此造成了大脑对颜色的感知，在这个200－800NM范畴，并形成‘颜色’来区别细微分布
reflect
use
a
is
black
plants
a
light-
left
wavelengths
scientists
的光 |
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h*h
发帖数: 18873 | 39 Cheese it, it's the geese!
Police in rural parts of China's Xinjiang Province are no longer turning to
dogs to stand guard at police stations at night. They're using geese instead
. And it works.
According to a recent report, a guy tried to break into a police station to
take back a motorbike confiscated by the cops. The guard geese sounded the
alarm, awakening the sleeping officers.
But ... really? Guard geese?
To gain insights into goose behavior, we spoke with Patrick Cumins, director
of bird... 阅读全帖 |
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s*********t
发帖数: 464 | 40 FUNDS CUT
In the last five years, 777 million were paid by the shareholders of Inter
and Milan: now there’s the stop.
Juve are different as they’re facing the deficit.
The Italian patronage is at dusk as if they want to adapt to the spirit of
the current time. Recession, the chase to balance budgets and of course the
financial fair play have said enough with the spending spree. Elsewhere,
however, spending money continues to run crazy from the sheiks, the
oligarchs, and even the Chinese. The que... 阅读全帖 |
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s*********t
发帖数: 464 | 41 It is true that the relationship between costs and turnover of Inter
(88%) and Milan (85%) are on the same wavelength as the crazy spenders in
Chelsea (85%) and Manchester City (114%).
relationship between costs and turnover 什么意思？貌似比率越高越不好？ |
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w*******y
发帖数: 60932 | 42 LaserMax Uni-Max Green Rail Mount Laser with Integral Rail:
http://www.amazon.com/LaserMax-Uni-Max-Green-Mount-Integral/dp/
This high-visibility green laser is compact, rugged, and fits Picatinny; Mil
-Spec; Weaver Style Rails (with minimum rail length of 1.75-Inch) Battery
Type: 1/3N Lithium (2) Accuracy: User-adjustable for windage and elevation.
Wavelength: 532nm (green) Power Output: 5mW. Spot Size: 5/16-Inch @ 7 Yds; 3
/4-Inch @ 25 Yds.
Highest visibility in ALL lighting conditions. Incredi... 阅读全帖 |
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w*******y
发帖数: 60932 | 43 2 in 1 Tool: Thermal Leak Detector + Infrared Thermometer
Perfect for Checking Temperature of Engine, Tires, Walls, Children & More!
Details:Description
Thermometers are used to detect a lot of different things. You can check the
temperature of your walls for heat/cold leaks to maximize your energy
efficiency, you can check the temperature of the grill to adjust for maximum
your steak grilling potential, and you can even check your child's
temperature without even getting close to them and riski... 阅读全帖 |
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j******g
发帖数: 1098 | 44 先zz一个帖子
全面的版本我要花点时间
发信人: Laputa (以德糊人), 信区: EEInvestor
标 题: 三维电影院匹克
发信站: BBS 未名空间站 (Tue Feb 9 00:15:40 2010, 美东)
皮克：IMAX (Imax theater), RGC (Regal Entertainment)， DLB (Dolby Lab)
这里简述一下技术哈。目前主要是四种技术：
1. Linear Polarizer : 主要是IMAX 采用。 被认为是过时的技术，
因为如果把脑袋侧过来的话就看不到三维效果了。
2. circular Polarizer ： 专利属于 RealD 的。 是主流三维影院
采用的技术。 主要优点是不受脑袋位置的影响。AMC, Regal 都用的
是 RealD 的技术。
3. Color wavelength multiplex ： 这个现在还没有普及,但是效果不错。
技术属于 Dolby Lab.
4. Shutter glasses : 忘了是哪家影院了， 好像只有欧洲才有。
IMAX 的主要优点是 popout 的效果比较明显... 阅读全帖 |
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L****a
发帖数: 572 | 45 皮克：IMAX (Imax theater), RGC (Regal Entertainment)， DLB (Dolby Lab)
这里简述一下技术哈。目前主要是四种技术：
1. Linear Polarizer : 主要是IMAX 采用。 被认为是过时的技术，
因为如果把脑袋侧过来的话就看不到三维效果了。
2. circular Polarizer ： 专利属于 RealD 的。 是主流三维影院
采用的技术。 主要优点是不受脑袋位置的影响。AMC, Regal 都用的
是 RealD 的技术。
3. Color wavelength multiplex ： 这个现在还没有普及,但是效果不错。
技术属于 Dolby Lab.
4. Shutter glasses : 忘了是哪家影院了， 好像只有欧洲才有。
IMAX 的主要优点是 popout 的效果比较明显， 所以小孩看会比较高兴。
RealD 则popout 的效果不太明显。
昨天的新闻说， J.P.Morgan 已经筹款 700M 给 RGC, AMC 建新影院。 |
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r*******y
发帖数: 1729 | 46 发现了这么一段，
Chyao created semiconducting nanoparticles that, when exposed to certain
wavelengths of light, generate a highly reactive form of oxygen that proves
deadly to cancer cells. Once injected, the nanoparticles could travel
through the bloodstream or stay localized in tumor sites. Exposure to a
targeted beam of light, like a laser, could catalyze the reaction
specifically where the cancer cells are growing.
This photodynamic therapy, treating superficial skin cancers with light, is
an esta... 阅读全帖 |
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r*******y
发帖数: 1729 | 47 I know nothing about cancer stuff.My understand is that this nanoparticle
under certain wavelength will release some reactive Oxygen to kill the tumor
... Her task is fabricating this kind of nanoparticle. Is that right? |
|
d**l
发帖数: 73 | 48 作者: rockitten (小貓) 看板: Military
標題: [書摘]Osprey伊朗空軍的F-14戰記
時間: Mon Oct 4 22:45:00 2004
以下內容一如以往：不入精華區
內容不錯，尤其是解答了不少有關伊朗F-14的疑問，如：
1.究竟伊朗接收了79架還是80架F-14？
答案：80架，只不過在回教革命時在美國準備接受美國空軍制式的空中加油設備，
所以1986年時被美國海軍改回美國版送給測試中隊使用
2.伊朗的F-14A和美國海軍的F-14A有什麼分別？
答案：伊朗的AWG-9和AIM-54和美國海軍的沒什麼分別，只在國會要求下change
working frequency/jumped wavelength慢了0.01秒、AIM-54的ECCM在對付
美軍ECM方面被downgrade，但伊朗版的F-14上的IFF(APX-82A)只能detect/
interrogate俄系的IFF。另外伊朗版的F-14也沒有航艦助降設備和不少data
link解碼器。
|
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l**p
发帖数: 474 | 49 Yes. The question is discuss teh limitation and impact of some factor on the
quality of image reconstruction.
a. overlap of spectral sensiticities of teh color receptors in eys.
b. the color reproduction primaries must produce engery at multiple wavelength
c. gye is nonlinesr for transmittance vs. concentration
d. the block dye is to expensive
e. The NTSC performace gamma correction on RGB at TV station instead of YIQ in
TV reciever
for teh e. how this will introduce any errors.. teh image qulit |
|
s******o
发帖数: 298 | 50 By Robert Roy Britt
Senior Science Writer
posted: 09:04 am ET, 05 April 2002
A systematic survey of the asteroid belt done in infrared wavelengths
indicates that there could be two or three times more large asteroids, those
more than 1 kilometer (0.6 miles) in diameter, than had been thought.
Based on observations of portions of the main asteroid belt, between Mars and
Jupiter, the new study estimates there are between 1.1 million and 1.9
million of these large space rocks. Many millions or perh |
|
