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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16
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3answers
2k views

Why is it more reliable to use the land/pit transition in a CD-ROM?

I was reading about how CD-ROMs work and I came to this: Although it might seem simplest to use a pit to record a 0 and a land to record a 1, it is more reliable to use a pit/land or land/pit ...
14
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2answers
612 views

Why are lasers used for concentrated light applications instead of incoherent light sources?

Some laser applications consist simply of concentrating light into a small spot. Two example applications are laser welding and cutting. In these cases a CO2 laser is often used which needs a ...
12
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4answers
3k views

Will more electricity be generated by using a lens to focus sunlight onto solar cells?

I have been wondering about this question for quite some time. Assuming an ideal case, the energy from photons hitting solar cells is converted into electric energy as described by the equation: $RI^...
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1answer
1k views

How does a microbolometer (IR camera) work?

I am currently doing a project which has led me to my first encounter with IR cameras, and I am therefore quite curious as to how they operate. Specifically, I would like to know the following How is ...
10
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1answer
1k views

What liquid crystals are used most frequently in displays?

Is there a specific chemical that is used frequently in the production of liquid crystal displays? During my internet research so far, it seems as if the specific chemical composition of the liquid ...
10
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1answer
904 views

What is the focal distance of an optical mouse?

I am trying to build an optical sensor for my old school, state property, standard french watt-o-meter. EDF ( Electricité de France ) has a gig which turns a wheel depending on watt consumption. The ...
9
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4answers
665 views

Can cameras+display screens with window/mirror-like optical behaviour exist?

Display screens connected to cameras are significantly different from windows or mirrors. Looking through a window or mirror, we can focus on infinity, and we can move our vantage point to see a ...
8
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1answer
128 views

How can I estimate blocking window distance in an sCMOS sensor setup?

I am trying to establish an appropriate distance between a spectrograph output window and a CMOS sensor. The spectrograph creates a focused image on the CMOS sensor but I am trying to restrict the ...
7
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4answers
7k views

Must rifle scopes have revealing reflections?

It's a movie trope that snipers are spotted because someone catches a glimpse of a reflection of the scope. It seems to me that this is a serious design flaw. I also know that a good number of scopes ...
6
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2answers
84 views

How to avoid dyed liquids staining reflective/transparent surfaces

I'm dealing with some hydrocarbons (diesel, gas oil, kerosene, ethanol) where I'm putting them in a chamber and shining light through them to hit a sensor on the other side in order to measure their ...
6
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1answer
300 views

What does 'easily reversed' mean in the NIST spectral database?

I'm trying to do some processing of optical emission spectra from sputtering plasmas, and am confused by what NIST means by 'easily reversed' in their notation. Anyone have a clue?
5
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4answers
7k views

How can I make a rudimentary sunspotter?

This is similar to my Physics.SE question Microtops sunphotometer sun target optics - there I was asking about the optics principles (the answer is no good for my understanding, but I have been able ...
5
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2answers
1k views

Transparent, hard material that lets infrared through

I am trying to build a protective enclosure for Microsoft's Kinect v2, which emits (and perceives) IR in the 827–850 nm range. In order to fully enclose the device without blocking those signals, I ...
5
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2answers
584 views

Do contiguous laser curtains exists? and if not are there any lenses that could spread a concentrated beam into a “planar” beam

The first photo is an example of a light curtain. I am certain that every individual beam is from an individual laser and receiver pair on both cases. Would it be possible to have one laser beam ...
5
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1answer
127 views

How does an ultrasound device determine where the reflection is coming from?

When the ultrasound transducer emits a signal and the signal comes back to the receiver how does the software or hardware determine where it came from? I understand it finds distance or depth by delay....
5
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1answer
326 views

How can I detect black spots?

I am researching about ways to continuously determine black spots (size 50+ micron) in our product stream. This stream consists of imperfect spherical polymer beads (size 3 mm) of different materials (...
4
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4answers
6k views

Why aren't screens round instead of rectangular?

Screens on TVs and phones et cetera are always rectangular. Why? Why are they not round? Eyes are round. The Sun, the source of almost all of our light, is round. Telescopes have round lenses and ...
4
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2answers
673 views

Periscope camera with a mobile phone, how to make walls not visible on the camera/alternative solution?

I am trying to make like a "periscope" that i can use with a mobile camera. I have made a very quick prototype with two mirrors and it "works" but you can see the interior of the walls so it is not a ...
4
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4answers
740 views

Precision measurement of liquid levels

How can I measure changes in liquid level of the order of 50 μm? The tank is cylindrical with a radius of about 12.5 mm and a total volume of about 45 ml. The fluid is water-based. The technique ...
4
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1answer
662 views

Focusing light from a laser shot into one point

I'm planning to build a laser shooting target. Something like this: In the long term I want to build something advanced like a professional grade target, in which the user is able to tell exactly ...
4
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1answer
5k views

Difference between continuous wave laser and a pulsed laser

I understand the difference between the two in terms of how they function; one will release all of it's energy in small pulses with the other creates a constant stream of radiation. My question is ...
4
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1answer
145 views

Modifying a fixed camera lens for close focus

I found this article on hacking macro lenses. The author used a lens extension tube to allow closer focusing. IE The lens's Minimum Object Distance (MOD) was significantly reduced. I cannot find an ...
3
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5answers
19k views

How can I measure the brightness of a LED?

I would like be able to measure LED brightness using a cost effective instrument. What are the available instruments to measure LED brightness and respective cost effective techniques? Background: I'...
3
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3answers
91 views

Why is the jacket or sheath of fibre optic endoscopes always black?

Why is the jacket or sheath of fibre optic endoscopes always black? Is it just a convention, or is there a more logical explanation for this?
3
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1answer
2k views

Building laser interferometer from CD/DVD drives parts

Is it possible to build interferometer, for linear displacement measurements, using old CD/DVD drive parts? I am talking about using parts such as beam-splitter, detector, laser and frame where it ...
3
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2answers
51 views

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 ...
3
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0answers
635 views

Optics for a triangulation laser distance sensor

I'm trying to build a laser distance sensor using triangulation (With this as my main inspiration, Webcam Based DIY Laser Rangefinder). My plan is to use a linear CCD array as the imager, such as the ...
3
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0answers
173 views

3D matrix for staggering 5 ten degree wide bands of angle of incidence shifted by target wavelength and optical path difference in arithmetic series

Today, we came up with the idea of creating a 3 dimensional matrix where I simultaneously stagger 3 times 5 times 5 Fabry Perot band-reject interferometeric filters with ten degree wide bands of ...
3
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0answers
129 views

Generating a IES file from an illuminaire and a lens

I have a IES luminaire file of a lamp and some polar candela distribution plots of lenses like: How can I create a new luminaire file combining the lamp with every lens? I could manually sample the ...
2
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2answers
74 views

Would connecting 100's of small telescopes into one huge telescope make for a significantly better telescope?

Not sure if this is a Physics related or Engineering related question, but imagine that we would take 100's of small hobby telescopes and somehow managed to point them all at the same point in the sky ...
2
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2answers
65 views

Lens to “stretch” or enhance vertical resolution in a photo

I'm trying to measure water elevation as a function of distance in a water tank, viewed through the glass wall, as shown here: The height variations that's of interest to me is very small. Would ...
2
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2answers
1k views

How to calculate meters per pixel for a given camera?

I am stuck on this problem for a while: I have a square-shaped camera, with: 1000 pixels on vertical side 1000 pixels on horizontal side I want to know the number of meters per pixel depending of ...
2
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1answer
58 views

What lens is needed for a retina scan?

I was originally planning to as this on Physics Stack exchange, but found this question while searching, which directed the asker to here. While my question is not a duplicate of that, it still falls ...
2
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1answer
594 views

How to focus the flashlight of a smartphone?

How would I go about collimating the light from a smartphone's flashlight into a more focused beam? I'm working on a project where I need a focused beam of light to act as a light source so I can take ...
2
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2answers
354 views

How does the Michelson interferometer measure the self-coherence function of coherent light in an incoherent background?

How does the Michelson interferometer measure the self-coherence function of coherent light in an incoherent background? Detection of coherent light in an incoherent background (Coutinho et al., 1999) ...
2
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1answer
289 views

What happens when very bright coherent light and weaker incoherent background light passes through doubly cascaded diffraction gratings?

Double diffraction is where a light beam passes through an grating with distance D1 between ridges and then passes through an grating with distance D2 The image after passing through diffraction ...
2
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1answer
27 views

Calculate FTIR-system response functions from measurements of a calibrated black body

I need to find the response of my FTIR spectrometer. I do have a calibrated black-body source (area-emitter) which I measured at various temperatures. The system operates in inverse cm, cm-1. My ...
2
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1answer
262 views

Design of Compound Elliptical Concentrator and Compound Parabolic Concentrator

What is the process in design a Compound Elliptical Concentrator and Compound Parabolic Concentrator if I wanted to achieve 100% optimal concentration ? Let's assume random numbers of: A light source ...
2
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1answer
38 views

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 ...
2
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1answer
129 views

What is the optical Lagrange invariant of an afocal system?

I am solving an optics exercise that requires to design a Keplerian telescope with a given magnification M (negative), a certain object size L and the restriction of not having lenses faster than F/1 (...
2
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0answers
87 views

how do tilt-shift DSLR lenses and video projector lens shift lenses work?

For photography there are tilt-shift lenses. For video projectors there is lens shift lenses. With video projector lens shift I get perfect, undistorted video projected up to 100% above, below, left ...
2
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0answers
464 views

What optics and display are used in Microsoft HoloLens?

How does Microsoft project an image so close to the eye yet understandable by the brain? How is the display transparent? This link has good information but is speculative. https://www.reddit.com/r/...
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3answers
760 views

How can I build a micrometer diameter laser beam from a common laser diode?

In order to build a lighting system for a microscope (with a digital camera) I want to make a very small diameter laser beam (parallel, rather than convergent). If possible around 1 um diameter. How ...
1
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1answer
73 views

Relations/Equations to do with light diffusing materials

I recently started as designer at a making custom signage (small signs viewed up close, so there are lots of sizing limitations) and none of the other designers have any solid rules to rely on for ...
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2answers
53 views

Optical methods for reaction engineering

What optical methods can be used to measure the concentration of reacting gases in a packed bed reactor during an exothermic and fast reaction? I need to monitor and measure the local concentration of ...
1
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1answer
1k views

Is it possible to reduce the divergence of a red laser pointer beam from 40 degrees to 1 degree?

I would like to find out if it is possible to reduce the divergence of a red laser pointer beam from 40 degrees to 1 degree. @Ruslan wrote on October 3 2013 that because the active zone of a ...
1
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2answers
116 views

How fast can a VEX robotics light sensor operate?

In my engineering class we must make a machine that can sort 15 marbles with 3 different types in less than 2 minutes. I plan on having one marble go over/under a light sensor with a flashlight on the ...
1
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1answer
57 views

Are DVD laser diodes single transverse mode?

I am looking for a cheap source of low power single transverse mode laser diode in order to focus them to a very small point. I thought I would get that from a DVD drive but the pattern I see at the ...
1
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2answers
113 views

Are thermal (LWIR) lenses as capable as visible-wavelength optics?

I'm trying to figure out whether lenses for thermal (long-wave infrared, i.e., 7-14µm) cameras are inherently more expensive or less capable than the lenses for visible cameras. Production lenses ...
1
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0answers
25 views

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 ...