Hello everyone. Can anyone provide a link to a document with information about the optical properties of FR4 epoxy fiberglass? I want to know the light transmission coefficient of the PCB core material for IR radiation. In many researches the refractive index is given, can I calculate the transition coefficient. from this?

Hi guys,

https://preview.redd.it/sl8ue7ip3m4e1.png?width=814&format=png&auto=webp&s=a891911d9c4131b977e0a32fc3a92a60e7f5dc9e

I'm trying to get the Fourier image(back focal plane image) from an objective. As far as I know there is a back focal plane of almost all lenses and that the back focal plane(BFP) of objectives are quite difficult to image as its BFP lies inside the barrel of objective.

My question is, how can Image the back focal plane to a detector(CCD camera)?

As far as the research I've done, I must add a bertrand lens to be able to image this back focal plane.
From the above reference, it is possible to put this lens just before the image plane(Fig 1a) or after the image plane(fig 1b) to image the back focal plane of an objective.

From the reference they suggest using an achromatic doublet lens as the bertrand lens. I have checked other references on how to image the back focal plane but this is the only reference that specified what type of lens the bertrand lens should be. Most of the the other reference describes the bertrand lens as lens that fourier transforms the image to the fourier plane. without specifying what particular lens they used to achieve it.

Is this correct?

Thanks in advance

Link to the reference: https://opg.optica.org/josaa/fulltext.cfm?uri=josaa-32-11-2082&id=331338

Cheers!

First-surface mirrors with R>97% work for the Fabry-Perot interferometer?

I am a physics undergraduate at Georgia Tech, and I have had research experience in optics/optical engineering all 3 years as an undergrad (with a somewhat decent GPA). I am one summer away from graduating and so I've been looking for a company internship for Summer 2025 as I'm looking to work in the industry after graduating. I've applied to many roles on Handshake/Linkedin and even with only about 20-30 applicants are applying, I have not heard back from a single company. Is there any advice that can be given regarding applying to companies in optical engineering? I have attached my resume just for reference. I appreciate you guys reading this post or giving any advice! Thank you :)

https://preview.redd.it/yf0t3t70si4e1.jpg?width=612&format=pjpg&auto=webp&s=ea165c24776218da25bed5566dd77579da12becc

Would be great to meet up!

Hi all, I want to simulate diffraction grating such that its period and depth of the grating should be defined. After that i want to measure the reflected and transmitted power when a source is initialized. Is there any way to simulate this?. I

Hi there!
I have noticed that my system drops since some step and OpticStudio provides error message "...TIR at surface N"

Have you any tricks and tips how to predict this in MeritFunction in advance? (my basic understanding to control ray angles, but it's started occur at another surfaces in this case)
May switching to the type "TrueFreeForm" help? If you were at the same situation, please share how did you solve it :)

Thank you in advance!

Hi,

I'm trying to figure out something but I can't find any explanation.
I came across this paper : http://dx.doi.org/10.3928/1081597X-20091209-05
which gave a relationship between the paraxial power of a lens and the zernike terms of the corresponding wavefront (from equation 7) :

S_para =( -4√6 C_2^0 + 12√5 C_4^0 )/R^2

where S_para is the power in m^-1, C_i^j are the RMS zernike terms in µm and R is the radius in mm.

I indeed checked using softwares such as Zemax that this is true, and I can derivate this easily from the second derivative of the wavefront.

What I can't figure out is the formula for the marginal power, which is not given in the paper. By doing the derivation myself, I find :

S_marg_deriv =( -4√6 C_2^0 - 60√5 C_4^0 )/R^2

But when I played with both Zemax and another wavefront simulation tool, I find the following relationship to hold:

S_marg_soft =( -4√6 C_2^0 - 12√5 C_4^0 )/R^2

This second relationship seems to give more reasonable numbers so I think it's the right one, I just can't figure out why it is true and why the number is -12 and not -60.

What are the difference among class a b c d,and what does "s"" mean in class as，I didn't find any explanation on this

I’m trying to find some resources on optical lattices from the basics (textbooks, papers, etc) but am having a hard time finding any.

Could anyone help point me in the right direction?

Thanks!

How can me and my group (4 people including me) create a simple adaptive optics for a university project? We can get the parts needed from our university and professor.

Level: Electrical Engineering Bachelor's 3rd Semester

Latest project is falling between macro and micro optics. I've lots of experience in the former, some in the latter. Sadly, the approaches that might be used [see e.g. tolerance table 5 in the open access article https://www.mdpi.com/2072-666X/14/6/1272] for micro-optics aren't going to be practical.

6.5µm thickness tolerances & 2.5µm decenter and runout? My machine shop would shoot my bullet ridden corpse, right after the glass grinders had finished shooting me.

Thanks, AoN.

So I am in the conception stages of designing a drum scanner but I have a question about the imaging optics, specifically the objective.

If you don't know, a drum scanner is basically a rotating acrylic drum that transparencies/prints are mounted to then light is shone from inside(for transparencies)/outside(prints). the spot of light is then sent through lenses and dichroic mirrors to seperate out r,g,b and then captured by photomultiplier tubes to scan the image pixel by pixel. The special thing is that in commercial drum scanners(when they were still made) had apertures(not sure whether it's before or after the objective) that defined the spot size therefore defining the pixel size and the PPI scanned.

I'm thinking of making an open source version of this using modern electronics. Onto my question. When picking up the spot of light, I was thinking of using a readily available infinity corrected objective then putting an aperture behind the objective before the dochroics and tube lenses that focus a light onto either a conventional PMT or an SiPM. Am I correct in thinking that a 50x magnifying objective with a 50micron aperture behind it would result in an effective spot(pixel) size of 1micron? Or am I completely wrong? I don't have much knowledge of optics so forgive me.

Edit: I drew a diagram of what I mean: https://imgur.com/a/TnSSjDX

Hi,

I am trying to build a raman spectroscopy setup in my lab and am struggling to get it to work! I am very very new to optics so I apologize if I am missing something obvious but please let me know!

I have attached an image of the setup. All I see is random noise that is probably coming from the laser. The maximum exposure I have tried is 2min exposures with 10 averages and I did not see any signal.

Details of the setup:

https://preview.redd.it/3xubm8p47z3e1.jpg?width=2016&format=pjpg&auto=webp&s=0fe9ec8e9ad1996841772a14d6e7e9f87c31393d

1. Laser -- We're using a 785nm diode laser and I put it at maximum power (200mW) while taking scans.

2. Sample -- I am using toluene as a test sample -- there is no real reason for it; was just available in my lab

3. Focussing the lens -- This is something Im not sure about -- how to adjust the focus of the lens correctly such that the light is concentrated onto the spectrometer. Part of the problem is that the laser is invisible so I have to make do with the laser viewing card. Since I have a 90degree geometry, I don't actually see the laser even at full power since most of the light just passes through the glass cuvette. I get around this by placing a translucent white paper around the cuvette so a lot of light gets scattered and Im able to see the light getting focussed by the lens. The lens and the fibre optic cable to the spectrometer are kept roughly so that the lens is focussed onto the fibre optic. The lens and the cable are placed in the parallel column thing (sorry I don't know the official name for it!) so that the lens is always parallel to the cable. I then removed the paper and moved the lens around slightly till it maximised the signal at the spectrometer.

4. Spectrometer I have is QEPro from Ocean Optics. It has pretty good resolution and is supposed to be sensitive. I can also do long time integrations on it. I believe it should be enough to see a raman signal but all I see is noise.

Any help at all is very welcome!

Thanks in advance.

I'd like to prototype some reflectors. What options do we have for making DIY mirror like surfaces? It there a thing like reflective Mylar pour on or paint on coatings?

Had to zoom in so the quality is crap, but I have no idea what model this is and I think it looks cool.

Hi, I've been trying to work this out for a few days but I can't find a consistent source on this issue.

I'm trying to calculate the final deviation angle of a beam after leaving a single mode fiber, being "collimated" travelling and then being focused again. I have all the component matrices but I'm unsure how to treat the incoming ray vector.

It's a 600um fiber with a numerical aperture of 0.067, I know the angle would just be the Na but do I have to include the 600um as the beam size? The impact of including it or not dramatically alters the results later on as I have ~1m of free space propagation after the collimator and the deviation added by including the fiber diameter adds a lot.

I find that measuring the system some elements match up with the including the 600um and some line up better if I neglect it. I'd love some more experienced opinionions

Thank you so much!

Little diagram here too.

This is the beam profile of my laser after 350hours of use. I was expecting a bit more of a gaussian profile. The M^2 is listed as <1.2 and i measured at 920nm at the tunable laser output. I am curious about the speckles at the right side. Any comments would be appreciated.

Thanks.

Not science based, for which I apologize.

Okay okay. Some festive engineering.

Every spherical or near-spherical element in a simple design has 15 16 tolerances (assuming they all drop into the same cylindrical bore). One approach to starting your tolerance sensitivity analysis could be to assume they add in quadrature:

(1516*num_elements*tol_sens^2 )^0.5 = accepteable_delta_mtf

=> tol_sens = accepteable_delta_mtf/(1516*num_elements)^0.5

Hello All,

Thanks for reading this post first of all but I would like to get some advices from you guys if possible.

I am currently working as an application engineer at a semiconductor company. We're working as a vendor for intel in Oregon. Before I was an application engineer, I worked as a field service engineer for e-beam products.

My question is..that how can I make a career change to an optical engineer?

I studied electrical engineering in 2018, but I didn't really take optic relevant courses and don't really have R&D experience. I've been thinking what would be the best way for me to make a career change to an optical engineer and I came up with few answers my own..

1. Apply for Master's at UofA next year.

• However, I am struggling a bit financially(i should be debt free by next year) and their online MS courses are expensive. $1300+ per credit hour..!
• I was thinking about on-campus option and I'd rather focus on studying for two years to complete MS but i need to quit my job, financially not stable as well.

2. Earn the Certificate program at UofA

• I hear its not good or worth it.

3. Studying my own/doing projects and keep applying jobs

• I get sometimes lost when I study or not sure if I am going in the right direction.

Sorry that english is not my primary language and happy thanksgiving guys

Suppose I have a double-concave lens whose curvatures are 100mm and 95mm, each. I guess the difference of curvature is noticeable if I use a sophisticated instrument like an interference meter, but just a glimpse of it can't see the difference. I want to use only a very simple and instant technique to see the surfaces separately without using a sophisticated instrument.

My interest is not to measure the curvature itself, but just want to see which surface has larger/smaller curvature to integrate it into a lens tube.

Does someone have any idea? If you share a very practical idea, I'd highly appreciate it.

Complete newbie to optics, so excuse me if this a bit of a simple question (I've tried to make ChatGPT explain it but well...):

I have a light source coming from two sides, say one straight and the other one angled 40° to the first one. I want these to be combined into a single image. Crudely drawn paint sketch attached.

I was thinking of either a prism (where I have no idea how to realise this) or something in the order of a half transparent mirror, that would let the "straight" light pass through and reflect the other into the path of the first.

Its supposed to be a practical solution, any help is appreciated.

I have an aspheric lens but I don't have an information about radius at curvature and focal point, I should make some technical calculations on zemax how can I measure radii of curvature of these lenses simple method ( I know newtonian rings method but I have not experimental setup )

Hi all,

I'm interested in the history of modeling EM fields focused by high NA lenses. As far as I am aware, the Richards-Wolf model addresses this problem by solving for all three field components near the focus of a Gaussian reference sphere given an input field at the back principal plane of the lens. It assumes the sine condition and energy conservation. The resulting integral is a sum over plane waves, weighted by the fields, some geometrical prefactors, and a 1 / k_z component.

This integral is also known as the Debye integral. As far as I can tell from literature referring to it, it comes from a 1909 paper in German: https://onlinelibrary.wiley.com/doi/10.1002/andp.19093351406

Given that there was nearly half a century between Debye's paper and that of R and W, I'm wondering in what context Debye did his work. Was it in Optics, or a different field?

Why do we call this integral the Debye-Wolf integral?

I've got a PSD of what the magnitude and spatial frequencies will result from polishing. Looking for a way to turn that into either a matlab propagation; I could use Zemax but never done MSF in Zemax; maybe a BRDF will work in non-sequential but dont know how to translate my PSD to a BRDF. Any advice or guidance on this?

Hi everyone, I have picked up an old Charles Perry inspection microscope (similar to these https://www.antiquemicroscopes.uk/m416.html) , low power and it has a binocular eyepeice. It has two fixed objectives mounted in a fixed angle and then the eyepieces are separate rotatable but have prism inside. I think it has been knocked or badly adjusted as the prisms are out of alignment. Does any one know of, or where, a good procedure to get them re lined up ? (you need to dismantle the tops and remove the eyepices to adjust the prisms, but then you can't view the result) Thanks!