What is Reflector: Definition and 48 Discussions

A parabolic (or paraboloid or paraboloidal) reflector (or dish or mirror) is a reflective surface used to collect or project energy such as light, sound, or radio waves. Its shape is part of a circular paraboloid, that is, the surface generated by a parabola revolving around its axis. The parabolic reflector transforms an incoming plane wave traveling along the axis into a spherical wave converging toward the focus. Conversely, a spherical wave generated by a point source placed in the focus is reflected into a plane wave propagating as a collimated beam along the axis.
Parabolic reflectors are used to collect energy from a distant source (for example sound waves or incoming star light). Since the principles of reflection are reversible, parabolic reflectors can also be used to collimate radiation from an isotropic source into a parallel beam. In optics, parabolic mirrors are used to gather light in reflecting telescopes and solar furnaces, and project a beam of light in flashlights, searchlights, stage spotlights, and car headlights. In radio, parabolic antennas are used to radiate a narrow beam of radio waves for point-to-point communications in satellite dishes and microwave relay stations, and to locate aircraft, ships, and vehicles in radar sets. In acoustics, parabolic microphones are used to record faraway sounds such as bird calls, in sports reporting, and to eavesdrop on private conversations in espionage and law enforcement.

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  1. H

    Designing reflector straight line lamp

    Who can help me to calculated a reflector for a straight light tube with a diameter of 6mm and a length of 300mm given a beam with a width of 100mm at a distance of 500-700mm?
  2. P

    Investigating the Sound Reflector of a Gas Inlet Tube

    My theory is that the gas inlet end, which is supposed to act as a sound reflector may not be doing a great job because it is plastic and has a hole cut in the centre for the gas inlet port. But by that reasoning, the flames at the end most distant from it (the sound inlet end) should be the...
  3. B

    Stargazing Troubleshooting My Orion 130 Reflector

    I have an Orion 130 reflector. Never had a telescope before. The field of view is about a quarter inch through the focuser with the 25 mm eyepiece. Does anybody know what I am doing wrong or if there is something wrong with the telescope itself? I'm at my wit's end. Any help would be...
  4. berkeman

    Hillbilly Fractal Antenna Reflector (and digital TV antenna suggestions)

    So the quality of my over-the-air digital TV reception has been getting worse over the past few months. Probably the digital TV antenna that I'm using is getting old and starting to degrade. Last night I resorted to trying different reflector combinations to try to boost the signal for the...
  5. E

    Two core regions with reflector

    Hello there I'm working on this problem: Solve numerically for the eigenvalue and neutron flux distribution in a slab reactor consisting of two adjacent core regions each of thickness 50 cm, with a 25-cm-thick reflector on each side. The nuclear parameters of the two core regions are (D = 0.65...
  6. Const@ntine

    Minimum Height of a Vertical Reflector

    Homework Statement Find the minimum height of a vertical flat reflector, in which a 1,78 m person can see its full reflection. Homework Equations M = h'/h The Attempt at a Solution I really don't know what to do here, and I feel as if I'm missing some crucial element. The chapter about...
  7. marellasunny

    500 kg Solar CSP reflector dish mechanism problem

    I am currently re-fabricating solar concentrator dishes to allow for automatic tracking of the sun during the day and month. The industry term for these dishes is 'CSP' (Concentrated Solar Power). Task at hand: The CSP parabolic dishes are currently manually adjusted to the position of the sun...
  8. Sebastiaan

    Using Gamma Ray reflector to reduce mass of Shadow shield

    Let's say we have manned space vessel powered by a highly power but radioactive rocket engine, producing a lot of deadly gamma rays. The classical answer to this problem is to use a shadow shield. However, Nuclear Shadow Shields are very heavy. What about the idea of instead of trying to absort...
  9. E

    How does Radiance change with a parabolic reflector?

    Lets say I have a coil that is 1cmx1cm in area that gets heat up. I am told that I get 2W/cm^2/sr output. So if I had 100 of them in an array, the total radiant intensity would be (2W/cm^2/sr x 100 x 1 sqcm =) 200W/sr. Now, let's say I add a parabolic reflector around each coil. How would I...
  10. kolleamm

    Stargazing Double image in reflector telescope

    Complete reflector novice here. Just got a reflector (using refractor before). I had no problems doing astrophotography with my refractor however with the reflector I get double images. Why is this so? Is this a collmination problem? It's not the camera because there's double images when I...
  11. P

    Best material to reflect for 35GHz RF

    Hello everyone. This is my first post.. I have been given the task of building some large RF reflectors that will reflect 35GHz RF energy. Can anyone give me an idea of what material / thickness of material I could use. For an example.. Would a pyramid made from wooden pallets covered in...
  12. V

    Stargazing Create homemade reflector telescope by own

    Can anyone please provide some web links or tips for making a homemade reflecting telescopes by own?
  13. S

    Stargazing Reflector telescope, what to do?

    Hey guys! My dad bought me a reflector telescope (Levenhuk Strike 120 plus) but I am having a hard time figuring out how it works. I managed to assemble the telescope with the help of my dad but we cannot seem to see anything through it. Any suggestions what could possibly be wrong with it? Or...
  14. neeraj kaira

    Decelerating Electrons & Releasing Energy: Reflector Plate Grid Dynamics

    When the beam of electrons reflect back to the grid due to the repeller voltage in reflector plate ,how the grid decelerates the returning electrons ?? And how they release their energy to the grid ?
  15. K

    Optics: Lens for capturing light from parabolic reflector

    I was wondering what type of lens would be best for capturing the light incoming from a parabolic reflector into a container? The Fresnel lens looks like a good candidate, but I am still not quite sure. Does anyone have any insight on this subject? Just for info, the parabolic lens redirects...
  16. O

    Ideal material for a parabolic reflector

    For microwave. Is it any insulator? Rubber will work?
  17. C

    How to obtain beam spread angle of a parabolic reflector?

    Hi i am new to the forum and hopefully i can get some help. I am trying to design a small parabolic light reflector that can be used with an LED array as being the source of light. The diameter of the LED array is 18.75mm. I am trying to obtain equations that would relate the diameter and...
  18. S

    Heat transfer through radiator reflector foils with data

    Hi all, We got these rad reflector foils to improve your heating bills in our shop today. Trying to figure out if there any good. As a really quick test to see if they do anything, i stuck one to the kettle and measured the temp difference with a thermal imaging camera. (pics attached)...
  19. I

    How can I design of a Corner Reflector antenna?

    Hello every body! Last weak I decided to make a corner reflector antenna for reciving TV signal.Now I need design and construction theory about it with total idea.I also need circuit diagram.Please share with me if anybody knows. sorry for my bad English. Thanks
  20. N

    Using a combination of a specular and diffuse reflector

    So l am designing a radiation detector using solid state silicon photo multipliers. On their website they tell me that the SiPM must be coupled to a Cs(Ti) crystal with a combination of specular reflector diffuse reflector film between the scintillator and detector. How does a combination of a...
  21. P

    Moving Reflector: Doppler Shift & Relativity Perspective

    Hey everybody. If I have a moving plane reflector with incident planar e&m waves, there is a Doppler shift in the reflected e&m wave, correct? So if the reflector is moving in the direction of the wave propagation, then the reflected waves are lower frequency then the incident waves...
  22. Who Am I

    Stargazing Zhumell Z8 Dobsonian. 8 inch reflector

    Well, I have a Zhumell Z8 Dobsonian. 8 inch reflector. It's kind of heavy, but is easy enough to transport. It didn't cost me much, under 400 I think. I am a big fan of it. I personally wouldn't ever choose portability over viewing quality, as long as I can move the thing. I'd always feel like...
  23. J

    Acoustic Levitation: Reflector Plate Challenges

    Hi everyone, I'm working a on a project involving acoustic levitation. Right now we're trying to finish up construction of the apparatus. In particular, the reflector plate is proving to be slightly difficult. The transducer we're use has a resonance frequency of about 29.95 kHz. As far I...
  24. S

    Magnetism and magnetic field reflector

    What can reflect,block or neutralize magnetism and magnetic field of a magnet?
  25. S

    How to calculate radius of curvature of a reflector

    Hi I need to calculate the radius of curvature of a reflector.I have a sound source (Ultrasonic transducer of 40 mm operating at 50 Khz) in air . I am trying to generate a standing wave using this sound source .As curved reflectors can help to amplify the sound pressure (I actually don't...
  26. S

    Why concave reflectors work better than a plane reflector

    Hi I have read several papers and found that for both sound beam /light beam , the sound pressure obtained is higher when a concave /curved reflector is used in place of a flat reflector. Can anyone tell me why? Is it related to soem consideration of energy loss from the wave? If...
  27. B

    Can Adding a Lens to a Small Solar Dish Increase Its Heat Output?

    Increase reflector output? Greetings, I have been workings on a Solar Tracker. I have some small TV sat dishes that I am planning to cover with Mylar to create the reflector. After viewing some videos on YouTube I noticed that a larger dish produces more heat. Would adding a lens increase...
  28. M

    How Can I Optimize Mirror Rotation for Vertical Sunlight Reflection?

    Hello everybody, I have made a sun reflecting system with sun tracer. I want to reflect sun rays into patio of a building with about 20 meter high. I have installed the system on the roof, opposite the sun and on th edge of the patio. I have used light sensors and have put them opposit to the...
  29. H

    Show that perfect a perfect reflector is a conic section with Fermat's principle

    Homework Statement Show, using Fermat's principle, that perfect reflecting surfaces are conic sections. Homework Equations Equations for the ellipse, parabola and hyperbola The Attempt at a Solution Ok, the ellipse seems easy. All rays coming from one focus reflecting to the other...
  30. R

    Water evaporation using solar reflector dishes

    Hi, we are running experiments with solar power; any inputs on below problem are highly appreciated. TNX Robby Project: We are experimenting how to maximize evaporation, using Solar Power. We have set up parabolic dishes with a fixed focus (Scheffler Reflectors). Each reflector can...
  31. P

    Short webpage title: Proving Equal Angles on a Parabolic Reflector

    Homework Statement Let P(x1,y1) be a point on the parabola y2 = 4px with focus F(p,0). Prove that the angles "a" and b" are equal, thus showing that a paraboloid will reflect all light from the focus in a parallel beam. Homework Equations Dont know of any The Attempt at a Solution...
  32. A

    Best Telescope: Refractor vs Reflector

    what is the best telescope? refractor or reflector? is the principle of reflecting is better or the reflacting?
  33. J

    Corner Reflector: Find Max Angle for Total Reflection

    [SOLVED] Corner Reflector Homework Statement A corner reflector is to be made from a triangular prism with index of refraction n = 1.86, as shown in the diagram below. What is the maximum angle, with respect to the normal to the front surface of the prism, θ, such that total reflection will...
  34. K

    Stargazing Gaze the Stars: Tips for High Schooler Stargazing in OC

    I just got a 500x reflector on Thursday. Gazing is pretty hard though because I live in OC and there's a lot of light pollution so its hard to make out most things in the sky other than the moon. Any tips for a high schooler's stargazing?
  35. R

    Exploring Neutron Population in Sub-Critical Reactor with Heavy Water Reflector

    Consider a reactor being held sub-critical, Keff < 1, by control rods. The reactor has heavy water reflector and has been operatored for some time prior to the current state (we got Photo Neutrons). Keff is then bought to 1. It seems to me, for Keff = 1 the neutron population should be...
  36. M

    Standing waves and a reflector

    When a reflector is added to the previous setup, as shown in Figure 9 (page 201), a standing wave can be created. We are using a different detector in this case. Measuring the detector output as a function of distance along the goniometer (look it up!), we see that there are maxima and minima in...
  37. B

    Discover the Power of Optic Solar Reflectors | Online Literature Recommendation

    Hellooo Friends Tell me what is optic solar reflector. Recommend me online literature
  38. C

    Stargazing Trouble Using Meade 2114 ATTS Reflector

    Well i have just recently received a meade 2114 atts reflector. I used it last Night and it seemed a bit complicated. I put it in the home postion and then let the autostar thing search and it either pointed at the ground or in a dark spot in the sky. It may have been the clouds but it seems i...
  39. Z

    Stargazing 14mm reflector with a 900mm focal length

    Here is a shot of the transit of venus as seen from Swansea, South Wales i used a 114mm reflector wiht a 900mm focal length with a Mylar solar filter. A universal t-mount fitter with a 20mm eye piece. mounted on the t mount was a Canon EOS 50E loaded with Fuji Superia XTRA ISO 200 film...
  40. S

    Cleaning a reflector mirror without scratching it

    Hi all. I have a very heavy 9" reflector but it is has spherical curve. It was made for a semiconductor projection aligner which was being scrapped and I saved the mirror from going into the trash bin. I saw an article in one of the rags about making a frame on the back of the mirror where...
  41. D

    Best material for a reflector?

    What material would be best to use when making a cylindrical reflector (antenna) for a 2.4Ghz signal?
  42. S

    PLz help me in this Corner Reflector Problem

    Hi! Well can u help me in this problem. it is related to a device called Corner Reflector. " A corner reflector is formed by three mutually perpendicular reflecting surfaces. Show that a ray of light incident upon the corner reflector (striking all three surfaces) is reflected back along a...
  43. S

    Please Please Please help me in this Corner Reflector Problem

    Hi! Well can u help me in this problem. it is related to a device called Corner Reflector. " A corner reflector is formed by three mutually perpendicular reflecting surfaces. Show that a ray of light incident upon the corner reflector (striking all three surfaces) is reflected back along a...
  44. S

    How Does a Corner Reflector Work to Reflect Light Back Along Its Incident Path?

    Hi! Well can u help me in this problem. it is related to a device called Corner Reflector. " A corner reflector is formed by three mutually perpendicular reflecting surfaces. Show that a ray of light incident upon the corner reflector (striking all three surfaces) is reflected back along a...
  45. N

    Skywatcher 5.1 parabolic reflector for DSO?

    Skywatcher 5.1" parabolic reflector for DSO? Hi, I've been scanning the night skies with my trusted 12 X 50 binoculars up until now and want to move onto a reflector for deep-space objects. Budget and portability have pointed me towards the below scope and i wondered whether any other...
  46. S

    Making reflector mirrors from spinning bubbles.

    I heard about a technique where mercury or some other liquid is spun in a dish until it assumes a parabolic shape. Would this work in space? Could a flat membrane of liquid metal do just as well? It could be liquified by an electric current and start out flat like soapy water in a bubble wand...
  47. P

    Buy a Celestron C-6N reflector

    I have owned 2 other types of telescopes previously and i am looking to buy a Celestron C-6N reflector. Does anyone have any comments on this scope? (+'s or -'s)