x*******i
发帖数: 32 | 1 Then there is no need for you to worry about movement of the focus. You can
control the focus movement of the stage using software. If you are using oil
immersion objective or water immersion/dipping objective, the stage
movement is equal to the focus movement. Otherwise if you are using a dry
objective, the stage movement is smaller than the real thickness roughly by
a factor of refractive index. One of the first papers to discuss this
artifact is Applied spectroscopy 2000, 54, 773. I remember ... 阅读全帖 |
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l**j
发帖数: 651 | 2 这个Stokes-Einstein equation算r为啥需要refractive index?
我就记得要viscosity了
function |
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E*******r
发帖数: 370 | 3 Difference in refractive index provides contrast for light scattering.
Contrast is needed for correlation function. |
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x*******6
发帖数: 994 | 4 S. Esmaeily, M. Kermani, M. Razavi, M.R. Rahimipour, M. Zakeri, An
investigation on the in situ synthesis-sintering and mechanical properties
of MoSi2-xSiC composites prepared by spark plasma sintering, Int. J. Refract
. Met. Hard Mate. 48 (2015) 263-271
多谢 |
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p*******8
发帖数: 158 | 5 Refractive index can also do the job but w/ low sensitive to impurities.
LC-MS is best instrument to fulfill your goal. However, you may not be
accessible to it. Go try polarimetry. |
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p*******8
发帖数: 158 | 6 Refractive index can also do the job but w/ low sensitive to impurities.
LC-MS is best instrument to fulfill your goal. However, you may not be
accessible to it. Go try polarimetry. |
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m*******e
发帖数: 119 | 7 For near normal incidence of light, the reflectance (energy
reflected) is:
R = ((n2-n1)/(n2+n1))^2
The transimission is T = 1 - R.
n2 and n1 are the refractive index of two media. |
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a******u
发帖数: 238 | 8 Not useful at all!hehe.
I still doubt the "negative" refractive index?
Is it real? |
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w********e
发帖数: 385 | 9 Scientists say they are a step closer to developing materials that will
render people and other objects invisible.
Researchers say they can redirect light around 3-D objects using
metamaterials--artificially engineered structures created at a nano scale
that contain optical properties not found in nature, according to an
Associated Press report.
People see objects as a result of the light reflecting or scattering off
them. This new mixture of materials has "negative refractive" properties
that k |
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a*******o
发帖数: 67 | 10 请问一个题目，哪位同学帮个忙
做助教的课的一个作业题，老师让我帮他做出来，光纤通信的题目，学了快2年了，忘
得差不多了，当时的课本也没带过来，这边的课本也借不到，而且我印象中这个题中很
多概念以前光纤通信都没讲过，我现在的项目也不是做光通信的，所以看了半天，实在
不知道怎么做，哪位同学帮个忙，先谢谢了
A plane TE polarized lightwave with vacuum wavelength λ0 is incident on the
interface between two dielectrics at an angle of incidence of θ1=86°. The
two dielectrics have refractive indices n1=1.50 and n2=1.49. The incident
light is propagating in the higher index material
a) Calculate the relative field amplitude in both media as a function of
d |
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R****a
发帖数: 199 | 11 First question for you, do you know the output power is one-facet or two-
facet?
Second, it would be very helpful if you could plot the L-I curve into (
photon number)-(electron number).
The refractive index n is used to calculate the reflectivity of the two
facets. (One simple question for you, do you know what that is?)
Another question, can we assume the confinement factor for current is 1? I
do not know much about bimolecular recombination, could you explain it a
little bit? |
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R****a
发帖数: 199 | 12 Just a quick check of your spectrum, you can see the mode spacing is about 0
.5nm.
So, the frequency difference is about 6.2e10 Hz (that is FSR of your F-P
cavity).
Assume the refractive index of your laser material is 3 (I do not know which
on you are using), the cavity length is about 0.8mm (your number is 1mm).
Given the roughness of this estimation, it is quite clear that those modes
are just longitudinal modes of your F-P laser.
Several ways to achieve single mode operation. You may check y |
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c******k
发帖数: 1140 | 13 When I am injecting current to the InP lasers, I am always using a thermal-
electric cooler (TEC) control, and the setting point of temperature is 20C.
So you are saying the 14nm wavelength shift corresponds 30-40C temperature
change. But because of the TEC, I don't think so the laser device could have
so high temperature change.
I talked to my boss, and he is thinking the larger wavelength shift could be
due to the refractive index change with the increasing of injection current
.There is a pap |
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w*******p
发帖数: 253 | 14 Usually the smaller step, the better accuracy, but more time-consuming.
Rsoft doesn't support localized mesh reshape, which means you can make the
meshes smaller in some critical region. So you have to live with that.
This is one of the software calculation tolerances I mentioned to you in
previous message, if the difference is within a certain range (for example,
diff steps give 0.1% difference in Neff), you can choose the bigger step to
save time.
Think about this, the refractive index you use |
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d****c
发帖数: 234 | 15 帮国内朋友发帖
领域：negative refraction of photonic quasicrystal
杂志： Laser Physics Letters
站内信，谢谢 |
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f*******r
发帖数: 1086 | 16 【 以下文字转载自 Physics 讨论区 】
发信人: flycooler (flycooler), 信区: Physics
标 题: 请教哪里可以找到stainless steel的折射率
发信站: BBS 未名空间站 (Mon Jul 2 14:26:30 2012, 美东)
小弟最近在做一个measure metal materials的项目，其中需要知道
stainless steel以及其他一些合金的refractive index 用来考虑
fresnel effect，但是在网上找了很久都没有找到，请问各位学材料或者物理
的老大们，哪里或者哪本书可以查到这些数据啊？(最好有对于不同波长的数据)
真心请教，忘不吝赐教，非常感谢！ |
|
x*******6
发帖数: 994 | 17 来自主题: Engineering版 - 求文献一篇 S. Esmaeily, M. Kermani, M. Razavi, M.R. Rahimipour, M. Zakeri, An
investigation on the in situ synthesis-sintering and mechanical properties
of MoSi2-xSiC composites prepared by spark plasma sintering, Int. J. Refract
. Met. Hard Mate. 48 (2015) 263-271
多谢 |
|
c*s
发帖数: 2145 | 18 it uses the different refractive index between substrate and your film...
more details, i dunt know.
But it requires that you know the approximate thickness beforehand, then it
will try-and-error and give you the value... |
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b**s
发帖数: 589 | 19 Film clarity is another method frequently used to distinguish between block
copolymers and homopolymer blends. The gross incompatibility characteristic of
most homopolymer blends results in opaque films due to a high degree of light
scattering at the interface between the two phases. An exception occurs in the
relatively rare case in which the two homopolymers have similar refractive
indices. On the other hand, block copolymers produce transparent alms, since
they usually exist in microphase- |
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c*s
发帖数: 2145 | 20 poly methacrylic acid ? |
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w********h
发帖数: 12367 | 21 寄信人: ukliaoliao (ll) [WWW MAIL]
标 题: need suggestion
实验需要一些颗粒，放在流化床中研究其运动性质。最好的材料是玻璃颗粒,glass
beads，但玻璃密度太大，2500kg/m3，所以就考虑用空心玻璃颗粒，但颗粒直径不能太小
，要大于50微米吧，找了半天没有结果。现在在考虑是否可以用polymer颗粒，因为polym
er比较容易得到尺寸一致的颗粒，而且密度也比玻璃小的多，但第一，不知道是不是透明
或半透明，或白色的，因为要用激光测量技术，要求颗粒具备一定的光学性能refractive
index，第二有机物颗粒好像容易带静电，尤其在流化床中，如何消除静电又是新问题。
有什么polymer particles推荐，如何消除静电等，亦或烦请转贴至高分子俱乐部，谢谢
。 |
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b**s
发帖数: 589 | 22 I used to work on the subject of gas phase fluidized bed olefin
polymerization, so I think polymer颗粒 fludization is not a big deal. you can
easily do it.
Try Polystyrene (because it can be polymerized directly into particle
form), But I think all the polymers are 透明或半透明，或白色的 if they are
pure.
静电, in my opion , is not a problem if you use steel fluildized bed
小
，要大于50微米吧，找了半天没有结果。现在在考虑是否可以用polymer颗粒，因为polym
明
或半透明，或白色的，因为要用激光测量技术，要求颗粒具备一定的光学性能refractive
。
谢 |
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b**s
发帖数: 589 | 23 Poly(vinyl acetate)
Catalog # : 347
CAS : 9003-20-7
Physical Form : Pellets
Approx Mw : 100,000
Density (g/cc) : 1.18
Refractive Index : 1.4665
Inherent viscosity : 0.42
Softening Point (C) : 97
TSCA : TSCA listed
Tg (C) : 30
Soluble in : Acetone, benzene, butyl acetate, carbon tetrachloride,
chloroform, dichloroethylene, ethanol, ethyl acetate, methanol, MIBK, THF,
toluene |
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b**s
发帖数: 589 | 24 Poly(hexafluoropropylene oxide) 1.3010
Alginic acid, sodium salt 1.3343
Hydroxypropyl cellulose 1.3370
Poly(tetrafluoroethylene-co-hexafluoropropylene) 1.3380
Poly(pentadecafluorooctyl acrylate) 1.3390
Poly(tetrafluoro-3-(heptafluoropropoxy)propyl acrylate) 1.3460
Poly(tetrafluoro-3-(pentafluoroethoxy)propyl acrylate) 1.3480
Poly(tetrafluoroethylene) 1.3500
Poly(undecafluorohexyl acrylate) 1.3560
Poly(nonafluoropentyl acrylate) 1.3600
Poly(tetrafluoro-3-(trifluoromethoxy)propyl acrylate) 1.3600 |
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z**h
发帖数: 224 | 27 the critical angle is determined by the average refractive index of the whole
sample. Does the average index change after annealing? I think only the
distribution changed. |
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c*s
发帖数: 2145 | 28
increase or decrease?
k=n^2 ba (n, refractive index, k, dielectric constant)
到:
reason? |
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w*z
发帖数: 35 | 29 So, decrease both refractive index and dielectric constant?
】
中提 |
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l*y
发帖数: 21 | 30 一个labmate说在polymer handbook找不到？？
高人指点哪里还有可能找到？ 或者您碰巧也用PEO? |
|
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E*******r
发帖数: 370 | 32 应该可以用带空洞的材料
加热或其他条件下一些基团能分解，在材料中形成空洞
就像有某种低介电常数的材料一样 |
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s****e
发帖数: 2934 | 33 嗯，空洞可以。另外就是避免极性分子和极性键。比如O，Cl，S |
|
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a*i
发帖数: 1652 | 35 that way, the material is no longer transparent... |
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a*i
发帖数: 1652 | 36 on the contrary, I believe polar bond should be adopted.
Fluoropolymers generally have lower RI. |
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a*i
发帖数: 1652 | 37 the refractive index of solution and mobile phoase should be quite different.
other issues to consider:
1) is the injection volume too small?
2) is the molecular weight too small (oligmer)?
3) what's the type of column? |
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r******0
发帖数: 2753 | 38 Most of them are polycarbonates. Some are also made of allyl resin. It is the injection molding pressure which changed the refraction index. High index lenses are made of materials that are compressed, or denser, so the same amount of visual correction is taking place using less lens material than traditional plastic or glass requires. |
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c******n
发帖数: 16403 | 39 Cool, thanks!
Mmd, simply by changing pressure can make such more money. My 2 new resin
lens (index=1.74) cost me 400 dollars.
the injection molding pressure which changed the refraction index. High
index lenses are made of materials that are compressed, or denser, so the
same amount of visual correction is taking place using less lens material
than traditional plastic or glass requires. |
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s****e
发帖数: 2934 | 40 呵呵，原来你是卖眼镜的
the injection molding pressure which changed the refraction index. High
index lenses are made of materials that are compressed, or denser, so the
same amount of visual correction is taking place using less lens material
than traditional plastic or glass requires. |
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n***s
发帖数: 1745 | 41 俺觉得是添加剂改变RI
俺们这里都是用无机盐类或者氧化物干这个活。
the injection molding pressure which changed the refraction index. High
index lenses are made of materials that are compressed, or denser, so the
same amount of visual correction is: -- |
|
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l*****g
发帖数: 556 | 43 RI yes.
Viscosity depends.
and |
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l**********g
发帖数: 55 | 44 Thanks, so how can I calculate viscosity? mass ratio or?
because when i use DLS for a mixed solvent, i have to enter the viscosity
and RI of the mixed solvent, that is where my question comes from.
thanks again!! |
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a********e
发帖数: 3771 | 45 Subjects with color deficiency needed for accommodation experiment.
$15 per hour.
This is a great experience to participate in research to understand the
factors that influence focusing of the eye.
There will be three sessions, each session will be about 1 hour. We will
measure your color vision (anomaloscope and D-15 test), your visual acuity,
and your refraction. We will monitor your accommodation and your pupil size
with a set of instruments while you view in an optical system stable or
sinu |
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c****l
发帖数: 25 | 46 Optometry在美国和中国几乎是完全不同的概念。在美国,Optometrist的职能包括
Refraction，Pathology，vision therapy,low vision, contact lenses fitting,是
被medicare以及其他insurance 承认的physician.与ophthalmologist不同的是，他们
不能够做眼科手术。在某些州，optometrist是可以作包括lasik 在内的激光手术的。
申请optometry school, 需要OAT成绩，以及math, biology,chemistry, physics,
psychology成绩。学费是一笔不小的支出，公立学校大约2.5-3万一年（州内学费）。
大多数美国学生毕业时的student loan 是$150000.毕业后如果选择作associate, 年薪
大概$80000. |
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e****0
发帖数: 678 | 47 • leukemia
ALL AML CLL
child adult elderly
BM lymphoblasts 25%myeloblasts
lab Lymphocyte 5000, mature-appearing cells
• Osgood-schlatters disease
Adolescent male athletes
Traction apophysitis—quadriceps tendon put the traction on the
apophysis of the tibial tubercle where patellar tendon inserts.
A firm mass =heterotopic bone formation
Pain can be reproduced by extending the kne... 阅读全帖 |
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L****a
发帖数: 106 | 48 请问版上的专业医生或有经验的给些介绍。一般性的介绍网上挺多，想听听专业医生的
看法，以及跟lasik的比较。多谢。 |
|
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f*******r
发帖数: 1086 | 50 【 以下文字转载自 Physics 讨论区 】
发信人: flycooler (flycooler), 信区: Physics
标 题: 请教哪里可以找到stainless steel的折射率
发信站: BBS 未名空间站 (Mon Jul 2 14:26:30 2012, 美东)
小弟最近在做一个measure metal materials的项目，其中需要知道
stainless steel以及其他一些合金的refractive index 用来考虑
fresnel effect，但是在网上找了很久都没有找到，请问各位学材料或者物理
的老大们，哪里或者哪本书可以查到这些数据啊？(最好有对于不同波长的数据)
真心请教，忘不吝赐教，非常感谢！ |
|
