Questions tagged [optics]

Optics is a branch of physics describing the behaviors and properties of light (electromagnetic waves). Questions regarding the properties of light, it's interactions with matter and the instruments used to detect and deflect (or concentrate) light should be posted here.

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Optical diffuser design

I have a small 3D printed SLA box, about 3.5" x 2.5" x 2". Here is the bottom half: And the top half with an LED inside, facing down, placed off-center, about 1.75" above the &...
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Make Multiple Displays Appear as One with Optics

I'm building a small information display using four 1.3" monochrome OLED modules positioned next to each other, powered by a microcontroller. I can configure these to act as a single display ...
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Bandwidth distance product formula

I read the following in one reference: A copper wire (twisted pair), the link traditionally associated with low bit rate transmission, is still in use in the modern data centers transmitting data at ...
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Can a very bright light attract an incoming laser guided weapon?

I would like to know if a very bright light will attract an incoming laser guided weapon such as a laser guided missile. Say for example that a tank has a six-foot pole on the top of it and attached ...
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Prototyping optics for laser rangefinder

I am a software engineer dabbling in optoelectronic systems. I can bumble my way through but I don't really know what I'm doing, and right now I'm figuring out how to prototype optical components. The ...
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What is the branch of engineering that deals with corrective eyeglasses?

So I was curious about what principle used to manufacture corrective eyeglasses. Of course it uses physics, especially optics. But what engineer branch or degree is needed to manufacture it? I ...
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Plus and minus power of Cylinder

This is my glasses prescription, is the cylinder minus applied at the meridians 180 and 10? So the the light is diverged at 180 and 10? Or does the axis value refer to the horizontal axis of a ...
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Angle of incidence in concave mirrors [closed]

What happens when you change the angle of incidence(normal to the mirror)? How does the angle of reflection change? Is it invariant?
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Dioptres of lens in glasses

If your glasses lenses have a +2.00D SPH and -1.75CYL. Does this mean the lens is composed of both cylindrical lenses and spherical lenses? For the Spherical lenses, if the diopetres is 2. The focal ...
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Determining the irradiance from radiant intensity and radiant flux

I am working with an LED spec sheet and would like to calculate the irradiance vs the viewing angle. The relevant data given is the following: Radiant Flux: $\Phi_{e} = 1930 mW$ A relative radiant ...
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4 votes
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Why does light bend after travelling half of the lens?

As light enters a denser medium from a rarer medium, it bends towards the normal. Why does the light bend after passing through point F & not E?
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Choice of lens for enlarging an image? Building a custom camera back

I'm investigating the feasibility of building an adapter for my medium format film camera to shoot Polaroid film. The normal film back for the camera uses 120 film, where on each shot a 60x40mm frame ...
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How can I visualize the phenomenon of Bound State in Continuum?

I am doing my Masters Thesis on Bound States in Continuum (BIC) and I am finding it difficult to visualize the concept. Is it possible to observe the phenomenon through an FDTD simulation? It is also ...
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How is light guided by a perfect mirror waveguide for angles not exactly at the guided mode angles?

Take the below image for example: Let's imagine the cladding is really just perfect mirrors, where all light energy is reflected back towards the core. I understand that modes arise by imposing the ...
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Please help to understand relation between simplified and real optical system for triangulation process

I'm far away from being an optical engineer, so I require some assistance. I have an optical system consisting of industrial camera and lens (manual iris + manual focus). 1)Lens documentation states ...
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Determining an adequate lens for collimation

I'm looking to develop an optical system to collimate a LED that is going to be fitted to glasses. I have a 5 mm diameter de-domed LED with a circular aperture that I need to produce a clean and even ...
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1 answer
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Why does my wall reflect green color when I shine blue light on it?

On the wall , i Walter had put a poster & when I removed the poster. I shone blue + red + white light on my white wall in the dark room. Under blue light only , I am able to see so many details. ...
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How can a screen be projected on a transparent glass?

I am building something similar to Google Glasses although not exactly that. I am trying to find a way to project my 0.96inch OLED on a glass, but it can't block the front view. What I tried to do is ...
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2 votes
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How can a small screen be projected on glass but still visible near 2cm from eyes?

In the smart glasses the images are projected on glass. But they are still clear to eyes. We usually can't see something clearly at such close distance. Then, how is the image projected from a small ...
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Optics: imaging a plane of a water spray/jet

I'm trying to think through a new experimental set-up, involving a sheet of water being shot up over a step structure. The water sheet will be about 5" wide, and the camera will be positioned ...
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Calculating Temperature of an Optical Fiber

Let's say there is 30W of light pumping into the fiber. Parameters: Length of Fiber: 6cm Input - 30 W Output -29W Loss of 1W The diameter of optical fiber is 0.25mm. Since the optical fiber is ...
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Heat loss in Optical Fiber

I am conducting a thermal analysis of optical fibers. ( Software used AutoCAD Fusion 360) The Inputs conditions are : Let's assume an input power of 1250W, with an efficiency of 98%. 2% loss which ...
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In-line holographic imaging: phase retrieval vs image reconstruction

I'm trying to understand holographic microscopy but I am getting very confused with the terms and methods involved. From what I understand in holographic imaging is that we can use the below integrals ...
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Which optical filter to use for flat black non-glare aerospace indicator?

I am currently designing a LED light indicator for use in an aircraft cockpit replica. I’m asking for expert advice on the type of lenses to use in order to get a result similar to shown pictures. ...
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Comparison of beam divergence between laser diode and DPSS laser

I'm currently comparing a pulsed laser diode and a pulsed DPSS laser. For the DPSS laser, the beam divergence is listed as "beam divergence (80% of total energy): $<4 \text{mr}$". The ...
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2 votes
2 answers
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Does this type of lens or light guide exist?

I am trying to create a line made from light projected from a lens / guide of some sort onto a surface from a few mm away. I have used a laser, but comes with safety considerations, space to mount the ...
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4 votes
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Alternatives to laser line?

I'm trying to project a very thin line at a low angle over some surface defects (peaks and troughs). The scale is ~20mm square, but the defects can be sub-mm (0.2 - 1.0mm). I am currently using a line ...
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How to multiplex several light sources into one optical path?

I'd like to design a device that takes 4 channels of light from sets of LEDs and multiplexes them into one optical path, which finally creates a rectangle pattern of light that is approximately 30mm ...
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Spectrometer design

I am looking to design a compact spectrometer based on using one single concave grating as both the dispersive optic and the imaging optic. I am investigating these gratings: https://www.edmundoptics....
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2 votes
2 answers
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Using phone screen as a barcode

I have this extremely minor problem where my gym is 4 blocks away, and I'd like to go over with nothing but my phone. Unfortunately, I have to bring a card with me for them to scan with a barcode ...
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Floating node in 4T CMOS camera pixel

I know how a 3 Transistor CMOS camera pixel works. As I understand, 4T CMOS pixels have one additional transistor that connects the photodiode to a so-called floating node. What is that floating node ...
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Home made microscope using donated objective lens and camera-ocular-adapter

I have a bunch of nice objective lenses from an huge old microscope set, and would like to make a microscope body tube with just one objective and one ocular lens. Without using trial and error to ...
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45 Degree Coupler on Fibre Optic cables

I was reading through a research paper and they showed the following schematic: I am not exactly sure what is meant by a 45 degree coupler so I looked online but there is no such thing as a 45 degree ...
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What is this part of a camera called?

Some cameras have a pattern similar to stairs close to their lens. For example: Such a system absorbs and/or reflects undesired light rays in order to improve image quality. How would you call such ...
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Can waste heat in specific environments be collected into photons and converted to electricity?

This question is a repeat of another post on the physics board Here and here show the possibility to combine photons of lower energy to higher energy. Thinking of an application, it could be used to ...
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Bicycle headlights with different low beam reflector types

What makes second reflector different than first one in terms of efficiency and correct beam distribution (brighter below cut-off line, dimmer closer to the ground)?
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2 votes
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Constructing small Kretschmann Surface plasmon set up

I am trying to build a SPR setup at home which is based off this diagram: I wanted to try to miniaturize it and had some concerns about my strategy. So I was thinking I could buy a big prism and ...
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Entrance pupil in an optical system

I'm challenging my optical design skills by coding a ray-tracing Python script. I know that many good packages exist out there, but I'm trying not to skips steps by building everything on my own. For ...
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Emerging beam from PPLN waveguide not behaving well through optics

We have a pump laser beam that is coming out of a single mode fiber and butt coupled into a PPLN waveguide crystal. We are capturing the beam at the output of the crystal with the focusing lens in an ...
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Passive Infrared Sensors (PIR) spectrum and reflections

I have a common PIR occupancy sensor (Lutron MS-OPS5M-WH). I am trying to get the sensor to cover an irregular-shaped room. I could expand the field-of-view of the sensor to cover the whole room by ...
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2 answers
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What power lasers can be used to heat fabrics to 70 degree Celsius?

For a project that I was building I wanted to heat fabrics to 70 degree Celsius using lasers. Since fabric is a very wide term for now I was looking to draw heat patterns on 100% cotton T-shirt and ...
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What does "coupling effects" mean in the context of optical systems?

What does it mean to say that there are "coupling effects" between some elements of an optical system? I've searched through the literature, but I cannot find a general explanation of what ...
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2 votes
1 answer
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How solid state lasers work?

In solid state lasers a light source pumps the medium, which is a crystal. A crystal is excited and emits infrared light, until then everything is clear. What I want to know: after excitement, what ...
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How to convey the image of a 14 mm object through a thiner (8 mm) pipe?

My setup and constraints are the following (see figure below): A rectangular pipe (~50 mm long, section 8 mm). The pipe has an apperture at one of its end, which is larger than 14 mm. A 2D object (a ...
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3 votes
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Differential Equation for: Locking a laser's frequency with a PI controller

I think I have a good understanding of differential equations, so I would like to first try to understand my system in terms of differential equations before transforming my system into the more ...
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How is a parabolic mirror made by hand?

So, glassmakers were tasked with building parabolic mirrors for telescopes. I imagine that process is now entirely done in heavily automated factories. How does one make a mirror and then carve it ...
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Connect LED with a 0.25mm fiber optic

I want to connect an LED (940nm signal) to a 0.25mm fiber optic. I have researched some possibilities, which involves using shrink heat tube, which is unfortunatly too large or simply buy couplers. I ...
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Meaning of SNR in Instrument Specifications

I am evaluating the specifications of an FTIR instrument (Bruker Vertex) and came across the following statements/items: Signal-to-Noise 5 sec sample, 5 sec reference: >10,000:1 (<4.34 x 10-5 ...
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3 votes
2 answers
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How to make a panel of LEDs appear to be a single source infinitely far away

I have a square panel of 100 LEDs (a series of LED strips). I would like to use some sort of optics setup to make this panel emit light that looks like it's from a single source at infinity. Is this ...
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Compound Microscope recommendation

I am an engineering student. I want to get into microscopy research and bio-science. So I want to buy a fair enough compound microscope. I searched for them and there are so many variants from ...
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