Questions tagged [optics]
Anything related to optics applied to electronics. Optics is a branch of physics studying the properties of light and its interactions with physical media.
99
questions
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1answer
96 views
Non-contact thermometers used by China in screening for coronavirus (2019-nCoV) [closed]
I'm not sure if this is off-topic, but if it is, then please inform me, and I'll delete it.
In media reports of the spread of the "coronavirus" (2019-nCoV), we often see images of Chinese officials ...
0
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1answer
49 views
Photodiode not working in reverse bias
I'm using a photodiode module, model: coaxial InGaAs, Gtel.
I set it in reverse bias with 5V and tested it with a laser but it doesn't give any output voltage. Unfortunately I don't know the laser ...
0
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3answers
206 views
Why does an optical drive use laser light?
Nowadays, lasers are cheap, but back in the day when CDs were first introduced, they were expensive. What is the reason for using a laser instead of a normal light source in optical drives?
2
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2answers
106 views
Can linearity of photoreceptor be improved by calibration?
I am trying to determine if equipment I already have can be used to take a reading in mcd/m2, for a quality control test. I have a sensor which meets all the requirements listed in the standard test ...
0
votes
1answer
27 views
How does one match irradiance to Luminous Intensity in Candela of source?
A light source has an Irradiance of about 1.6 W/m²/nm at wavelenght 385nm and an LED:
Peak Wavelength 385nm
Viewing Angle 30 °
Luminous Intensity 80 mcd
If this light source shines on a ...
2
votes
4answers
592 views
How to make affordable DIY low-res absolute rotatory optical encoders with fibers? [closed]
I have zero knowledge of optics and want to make a very low resolution (~10°) absolute rotary optical encoder using rapid manufacturing (I have 3D printers, laser cutter, and desktop CNC). Digging the ...
1
vote
1answer
74 views
Do electronic fiber optic selector switches exist?
From my research, I have been having a tough time finding and specifying a fiber optic selector switch or multiplexer. Do fiber optic selector switches exist?
Background - Simple
I have an ...
0
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1answer
37 views
How does a fiber optic receiver converts the optical signal to an electrical signal
A fiber optic receiver needs to convert the incoming optical signal to an electrical signal so it can be sampled. How is this achieved in practice?
I believe a photodiode is used, but would a ...
0
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1answer
70 views
Help me to build some devices for measuring LEDs optical power[mW] with range (1 -100)mW included [closed]
I have an application of photoactivation device with 10-20 LEDs for every color; with the following wavelengths : red 630-670nm ;yellow 575-595nm , green 510-540nm .
In order to obtain an uniform ...
0
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2answers
50 views
Specificity? “High-Contrast and spectroscopic-based specificity of optical imaging.”
I came across the following phrase:
High-Contrast and spectroscopic-based specificity of optical imaging.
I'm wondering what is meant by "specificity" in this context?
Thanks for any ...
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1answer
71 views
speed of light measurement [closed]
u can video call one smartphone from another via wireless internet connection, ie: the signal travels from one device to a satellite and then to the other device. but i want to avoid network noise and ...
0
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1answer
74 views
Classification of LED type
Out of curiosity, I recently opened a damaged measurement device (it´s some kind of lab spectrometer, but I am not sure) that contains a LED with a package like I have not seen before (see picture).
...
0
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2answers
125 views
Measure laser with photoresistor (LDR)?
I want to make a simple setum, where I can measure the opacity of air. I want to use a simple laserbeam, which I shoot across the room, and on the other side I want to measure how much is blocked/...
1
vote
0answers
51 views
Generate ultrashort rise times with photoconductive switch or photodiode
I am trying to produce voltage pulses with very short rise time (<15 ps), medium width (20 ns) and amplitudes up to 15 V. As a promising candidate I selected photoconductive switches and ultrafast ...
1
vote
1answer
70 views
Material dispersion in fiber optics transmission
In plain English, why does material dispersion increase with wavelength in fiber optic transmission? I am aware that refraction index decreases with wavelength increase, i.e. pulse travels faster, but ...
1
vote
4answers
181 views
Fiber-optic transceiver ICs for applications other than fiber-optic Ethernet? [closed]
When we talk about fiber-optic transmission, we almost always talk about copper to fiber-optic Ethernet conversion using fiber-optic transceivers.
But since fiber-optic communication is just ...
2
votes
1answer
282 views
Reducing LED spread via pinhole
I am making an infrared break beam to detect insects, using an IR emitter LED and detector. The insects fall into a channel and then eventually cross the beam, which travels the length of the channel.
...
1
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1answer
148 views
wifi baseband access
I've got an unusual use case (optical communications) that would benefit from access to the wifi baseband signal before it is upconverted/modulated at 2.5Ghz. However most modern wifi chips combine ...
0
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0answers
125 views
concave conical lenses on 5050 SMD LEDs?
Is there any way to put plano-convex conical lenses, or something broadly equivalent, on 5050 SMD LEDs?
The lenses I'm talking about are the type commonly built into cheap christmas-tree lights:
As ...
1
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4answers
499 views
Method to determine angle of a rotating stage
I am currently working on a project that requires the rotation of polarizers to very specific angles. It is necessary that we are able to determine what angle the polariser is currently at so that we ...
1
vote
1answer
79 views
principle about SPAD for ToF ranging module from ST
My colleagues are using VL53L0 from ST which is one ToF ranging module. I am trying to understand the principle about the SPAD(single-photon avalanche diode) and have read many materials on it.
From ...
4
votes
2answers
211 views
How does a CD or DVD burner produce submicron lines separated by submicron distances?
What mechanism(s) are used to achieve repeatable submicron spacing between concentric tracks in a DVD, CD, or other optical writer? I want to understand the minimal set of hardware used to achieve ...
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votes
1answer
62 views
Is NeoPixel used in Amazon Echo series? [closed]
Is it true that NeoPixels are used in Amazon Echo series?
If so how many NeoPixel LED's are used?
If so what are the optics used to give a smooth streak of colours?
1
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4answers
263 views
When will electromagnetic waves reflect? What are the criteria for reflections?
When an EM Wave comes to a boundary of two different media (i.e different electrical permitivity and magnetic permeability media), the things below could be seen:
Reflections
Refractions (...
0
votes
1answer
64 views
Is the infrared sensor fabrication process(Using such materials HgCdTe, InSb, InGaAs) different from CMOS fabrication processes ?
I want to learn differences between Infrared sensor fabrication and standard CMOS IC fabrication. If I am not wrong, in standard CMOS fabrication Silicon is mostly used. But for infrared spectrum such ...
0
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1answer
217 views
What is the advantages of InGaAs infrared image sensors? [closed]
I am currently searching the InGaAs material for infrared imaging usage. I have read some papers about it. It seems a new one. But I can not get real advantages of it, yet. What is the basic reason(...
1
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1answer
51 views
Migration from multimode to single mode fiber
In my company we are using custom measurement systems with multimode fiber optic transmitters and receivers for synchronization between different devices. We are thinking of migrating our multimode ...
0
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3answers
422 views
Relationship between optical power and drive current/voltage?
For a project I'm working on I've got a laser diode whose spec sheet lists the optical power and operating voltage of the module. Unfortunately, the parameter I need most is the drive current. Can the ...
0
votes
0answers
60 views
Place of matched filter in fiber optic communication
In short-haul communication via optical fibers, we use photodiodes (PD) to detect the light. So if we want to use a matched filter, should we use it before the PD (optical domain) or after the PD (...
0
votes
1answer
529 views
Solid angle measurement conditions for radiant intensity specification in IR-LED's data-sheets
For some IR-LED's their data-sheets state Radiant Intensity and the conditions under which
that number was obtained, indicating also which solid angle was used for the measurement.
For example, this ...
0
votes
1answer
120 views
Symbol rate and optical bandwidth relation
I am quite new to the field of optical communication, so perhaps this question is so easy.
In reading some papers I have faced to the concept of optical bandwidth. For example, they say the symbol ...
1
vote
2answers
1k views
what is the span of an optical fiber?
I am new to the fiber-optic communication systems, and in reading some relevant papers, I faced to the term "span length" (such as long-span link) which I cannot distinguish it from the length of the ...
1
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1answer
189 views
Determining LED safety compliance
I have a compliance audit that has been foisted on me from on high - as part of what an external consultancy has highlighted, I now have to prove that the indicator LEDs on a board I designed a long ...
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2answers
89 views
Is it guaranteed that fingerprint data taken by a scanner can be reused by another scanner? [closed]
I want to create a system that records employee attendance with optical finger scanner. Because the scanner has a limited lifetime, replacement with the same kind in the future might be impossible due ...
2
votes
6answers
6k views
Can camera sensors be damaged by light?
Suppose a 3.3 V white (or any colour) LED with a current draw of 20 mA is shone into the lens of a cheap webcam (or any budget camera) at close range (< 3 cm) for a long period of time (24 hrs) or ...
0
votes
1answer
120 views
How are the frequencies in 50 GHz channels in DWDM networks used?
In optical DWDM networks, the spectrum is classically divided into several 50 or 100 GHz channels.
So, let's assume some channel ranges from x to x+50 GHz. On which frequency/frequencies is the ...
3
votes
2answers
129 views
Optical Communication Two Sources One Receiver
I'm working on a project that requires me to wirelessly transmit analog information over a short range (few meters at maximum) to a receiving end from two transmitting ends. The tricky part is I can ...
0
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2answers
69 views
Low-cost way of shining a wide line of light, kind of like some bar code scanners do [closed]
What is a cost-effective way (say roughly $15) to shine a wide but thin beam of light, directly away from the source, so that it would project a line onto a nearby surface?
My particular beam would ...
1
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1answer
62 views
What is anti-reflection coating and in which application it is used?
I would like to know about anti-reflection coating and I am interested to know whether this can be used in antenna design also.
0
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3answers
75 views
detect optical transceiver transmit wavelength
Let's say there is a no-name SFP transceiver without a label and without DDM(allows to see manufacturer programmed wavelength data on EEPROM from network device) support. Is it technically possible to ...
4
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2answers
896 views
Atmospheric attenuation calculation for a 1550nm link budget
My apologies in advance if this is the wrong place to ask this question. I was told that there were some RF communications experts here, so i figured there might be some FSO experience here as well.
...
0
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1answer
403 views
How to measure air quality (especially PM2.5) from distance (scanning like a LiDAR)? [closed]
I have a bit of experience in measuring PM2.5 (fine particles in the (ambient) air 2.5 micrometres or less in size) using PMS5003 sensor. This sensor uses laser, photodiode and the fact that the air ...
0
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1answer
55 views
Group velocity dispersion for coupled waveguide system
I am an EE undergrad currently studying group velocity dispersion (GVD) for coupled waveguides, and am quite confused on the following question: how do you characterize group velocity dispersion for a ...
0
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2answers
141 views
Complete fiber optic transmitter and receiver with standard fiber optic connector and integrated power circuitry? [closed]
I am having a very difficult time trying to find a simple, completely self-contained module to convert digital signals (<2Mbps) to fiber optic, that uses a robust, standard fiber optic connector (...
0
votes
1answer
172 views
what dependence does the intensity of a normal LED(the one used for DIY projects) follow with respect to distance? [closed]
What is the dependence of my led's output with respect to distance.
I am guessing that since the LED inside the glass pane it is somewhat like a wire. Thus, it might follow inverse proportion with ...
2
votes
1answer
369 views
How can I estimate the readout time of an electronic camera shutter?
I would like your help in finding a way to estimate the readout time of a digital camera's rolling (electronic) shutter. Meaning, the time that it takes to scan a frame. I looked through the internet ...
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1answer
94 views
What electronic component is this? - sensor part of particulate matter sensor [closed]
What electronic component is this?
This is a part of a laser sensor which measures particulates.
0
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1answer
161 views
Can I use sfp+ transceivers to interconnect PCIe x1 lane?
This is interesting because, sfp+ offers an inexpensive way to use optics to connect two PCIe x1 devices. But I do not know enough about sfp+ to know if I can simply connect up pcie lanes on a ...
0
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1answer
140 views
Dual layer DVD question
I'm curious how a laser knows which layer to read in a single side dual layer DVD. It seems like it could easily read data from the second layer while it's shining through scanning the first.
1
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2answers
581 views
Ultra low ripple constant-current LED driver design
I designed a LED driver(SMPS configuration) with ILD6150XUMA1 and below is the circuit. I used it with AC/DC adapter. The thing is, th optical system is ultra sensitive and ripple from the LED ...
