What is Projector: Definition and 49 Discussions

A projector or image projector is an optical device that projects an image (or moving images) onto a surface, commonly a projection screen. Most projectors create an image by shining a light through a small transparent lens, but some newer types of projectors can project the image directly, by using lasers. A virtual retinal display, or retinal projector, is a projector that projects an image directly on the retina instead of using an external projection screen.
The most common type of projector used today is called a video projector. Video projectors are digital replacements for earlier types of projectors such as slide projectors and overhead projectors. These earlier types of projectors were mostly replaced with digital video projectors throughout the 1990s and early 2000s, but old analog projectors are still used at some places. The newest types of projectors are handheld projectors that use lasers or LEDs to project images. Their projections are hard to see if there is too much ambient light.Movie theaters used a type of projector called a movie projector, nowadays mostly replaced with digital cinema video projectors.

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  1. ergospherical

    I Pullback & orthogonal projector

    We have a map ##\phi : M \rightarrow N##, where ##N## has dimension ##n## and ##M## has dimension ##m=n-1##. So we consider the hypersurface ##\Sigma \equiv \phi(M)## picked out by the map. We also have an orthogonal projector, ##{\bot^a}_b \equiv \delta^a_b + n^a n_b##, where ##n## is the unit...
  2. A

    I Reverse Projector: New Tech for Immersive Video Experience

    Good morning physicists, I have a small problem, having a sony projector, like all projectors I always have the usual problem of image pollution. I heard a few months ago (but now I can no longer find the link), of a new technology according to which the projector instead of projecting on the...
  3. A

    I Projector location in Cinema Theater

    The projector location in Cinema Theater can be positioned in Top left corner, Center, Top Right corner etc? I mean Can the projector location in a Cinema Theater can be anywhere at the top of the wall? Attached Screenshot.
  4. T

    B Visit to Hayden Planaterium -- The projector is gone?

    As a kid I always liked going to the Hayden Planetarium. Stars were projected on the dome that a city kid could only dream of seeing.But that was a long time ago.I went there recently and the projector is gone. They now show movies projected on the dome with some special effects.Don't you...
  5. S

    Building a small pattern projector

    Summary: calculation a projection lens system for a pattern projector Summary: calculation a projection lens system for a pattern projector Hello, I want to build a small pattern projector. This projector should project a pattern on a wall, which is 200mm away from the projector. The size...
  6. PhysicistSarah

    What to Do With TV Projector Optics?

    Summary: Got some high quality lenses. hat can I do with them? I acquired some high quality optics from a projector style TV that I took apart for it's mirror and a few other things. I got some high quality lenses though. I'm interested in astronomy and physics demonstrations because it gets...
  7. H

    Optical Simple optical lens design help (small projector)

    I need to design a mini projector as a part of a project I am working on. The body of the projector is approximately 7 inch tall and 5 inch wide. I don't know what kind of a lens I need to ensure the projection is sharp and crisp (it is only black and white writing). I know I would need a zoom...
  8. N

    The use of plano convex lens in a slide projector

    Hello My question has two parts: 1) Why is plano convex lens used in slide projector? Why can't we use simple convex lens in it? 2) Why are two plano convex lenses used in slide projector? Why can't we use only one?Thanks!
  9. prashantakerkar

    Smartphones with inbuilt projector circuit

    Is it feasible to design and construct State of the art Smartphones with inbuilt mini projector device functionality ? As we know there is a inbuilt torch feature in the Smartphones but has limited functionality. If not, Why? Thanks & Regards, Prashant S Akerkar
  10. M

    Imaging optics and lowest possible angle video projection?

    I have a very very unusual project requirement where I need a pocket video projection with the lowest possible projection angle or "longest possible throw-ratio". It's a pocket DLP projector so goal is to have the beam remain ,as much as possible, almost the same size as the DLP matrix, for a...
  11. W

    A How spin projector got included in inverse of Matrix?

    The following matrix A is, \begin{equation} A= \begin{bmatrix} a+b-\sigma\cdot p & -x_1 \\ x_2 & a-b-\sigma\cdot p \end{bmatrix} \end{equation} The inversion of matrix A is, \begin{equation} A^{-1}= \frac{\begin{bmatrix} a-b-\sigma\cdot p & x_1 \\ -x_2 & a+b-\sigma\cdot p...
  12. G

    How does changing projector lenses affect brightness?

    I have some questions about projection lenses and screen brightness. Background I may be purchasing a BenQ PU9730 (http://www.benq.com.au/product/projector/pu9730/specifications/) for use in a large venue, projecting an image 3 x 5.3 metres. The projection booth is 18m from the screen (maximum...
  13. G

    Image is inverted when I look into a projector lens -- Why?

    I'm using a film projector as an editor, meaning I run the film slowly and use a low power bulb. I want to minimise any possibility of damaging the films. To view a film I simply look straight into the lens – and I see an inverted image. What I can't explain is why the projected image appears...
  14. J

    Small Reflective Projector LCD

    Hello, I need some assistance on a current project I'm working on. Here is some basic background information: I am currently trying to use a "makeshift" SLM, spatial light modulator, to impose a diffraction pattern so that when I shine a laser on it, the beam is diffracted into a donut shape...
  15. Avijit Palit

    B How to increase brightness of projector

    I have made a smartphone projector. But is has low brightness. How to increase brightness of projector... Help please
  16. D

    Why Is There a Black Line Moving Across the Screen?

    from a bit of googling, i realize it's because the frame rate of the camera and the projector are different. however, i have tried recording videos with cameras of 60fps, 30fps and 15fps, and the projector is likely 60 fps. That's why I'm curious about this - which frame rate is faster (the...
  17. G

    Determining the brightness on a projected surface

    I'm trying to determine how bright my projection image will be on a projected surface. I'm struggling to find a formula for this. I'm using (for example) the Canon Rialis projector which is 4500 lumens. I would be using the zoom lens with maximum zoom so the throw ratio would be 7:1. At a...
  18. N

    What lenses and setup should I use for a very narrow beam projector?

    I am working on a project where I have to project a logo on a very narrow angle like shown below: The projection distance will vary between 6-10 yards and at 10 yards the projected diameter will not be larger than 12inches so the beam angle needs to be less than 5 degrees. The idea is to...
  19. P

    Very small holographic laser projectors and diffraction.

    In thinking about what it would take to make a feasible invisibility cloak or holographic disguise or perfect hologram room, I've imagined something that works like this: A light beam "image" is projected onto a device designed to refract or reflect it in all directions, but only 1 color in any...
  20. L

    Projecting an image back into a slide projector

    Hello, I am working on a project in which I want to project a projection back into a slide projector using a concave mirror. The lens of the projector has a focal point of 100mm (and an aperture of 2.8) and I want to have approximately 1 meter space between the mirror and the...
  21. Moezeus

    Simple Projector (can you help me?)

    Hello everyone ! i want to make a simple projector using a convex lens, is it possible ? i don't think want to make it as same as the real projector, which using a mirror inside (i don't know for sure, but my senior told that). when i search for some solution in google, i get some, but maybe...
  22. C

    Can a single lens save the day for the broken projector?

    Homework Statement You have paid big bucks to see The Bourne Legacy at the 3-D IMAX theater in Vancouver. Just before the movie is about to begin, the theater staff tell you that the lens for the projector has just broken! You really want to see the movie and decide that it should be simple to...
  23. G

    How to optimise stiffness for a projector screen?

    I am thinking about building a projector screen out of MDF. Here Down Under the available sizes are: http://www.misterplywood.com.au/products/mdf. Building such a screen will be easier than the normal frame with stretched fabric type, but I am concerned about its long-term flatness. So I thought...
  24. K

    Converting XG-NV2U LCD Projector to SLM

    I am currently trying to convert an old Sharp XG-NV2U LCD Projector into a spatial light modulator, and have gotten stuck. The panels don't seem to be interfacing with the computer anymore, which is a problem since I want to use them to project diffraction gratings. Using two polarizing...
  25. C

    Help Solve Lens Projector Distance Puzzle!

    I have this in my home work and i am not 100% on if i have it right or not A converging lens with a focal length of 25 cm is used to make a slide projector. If the image is to be projected onto a screen 10m away, how far should the lens be located from the transparency? I did it like...
  26. mishima

    Pinhole Projector: How Many Photons, How Small a Hole for Shape?

    I'm confusing myself trying to explain the pinhole projector (card with pin point hole used to watch eclipses). How many photons are required, or how small a hole could you maintain, to still get the apparent shape in the projection? Why? Obviously only one photon isn't enough to describe the...
  27. B

    Solving the Mystery of the Broken Projector: +5.5 or +6.5?

    Homework Statement You have paid big bucks to see Season of the Witch at the 3-D IMAX theater in Vancouver. Just before the movie is about to begin, the theater staff tell you that the lens for the projector has just broken! You really want to see the movie and decide that it should be simple...
  28. A

    Projector Operator: P^2, Eigenvalues & Eigenfunctions

    An Operator is defined as P|x> = |-x>, 1. Is P^2 a Projector operator? 2. What are the eigen value and eigen function of P?
  29. R

    Solving Projector Question on Mixed States

    A few months ago I wrote this line down, but it does not seem to follow any more. Am I mistaking a mistake now or when I first wrote it down? thanks ( | 0 \rangle \langle 0 | + | 1 \rangle \langle 1 |) \rho ( | 0 \rangle \langle 0 | + | 1 \rangle \langle 1 |) = | 0 \rangle \langle 0 |...
  30. T

    Projector augmented wave method

    Hi all, Did someone can explain me how this method is working? I know that PAW unifies all-electron and pseudopotential approaches using some transformation operator that is suppose to smooth the true wave function into a auxilary wave function that can easily be represented by a plane...
  31. M

    2-norm of a projector is greater than 1

    Let P \in \textbf{C}^{m\times m} be a projector. We prove that \left\| P \right\| _{2}\geq 1 , with equality if and only if P is an orthogonal projector.I suppose we could use the formula \left\| P \right\| _{2}= max_{\left\| x \right\| _ {2} =1} \left\| Px \right\| _{2} and use the fact that...
  32. M

    Projector Matrices: Conditions for A=uv*

    Consider the matrix A = u v^{\ast } where u, v \in \textbf{C}^{n}. Under what condition on u and v is A a projector?A is a projector if A^{2}=A , so we have u v^{*} u v^{*}= u v^{\ast }. Does this imply u v^{\ast } = I ? And what exactly are the conditions on u and v that they are asking? do...
  33. M

    Prove: Normal Projector iff Self Adjoint

    How do you prove that a projector is normal if and only if it is self adjoint? I know a matrix P is a projector if P=P^{2} and P is normal if PP* = P*P and P is self adjoint (or hermitian) if P= P*. I think I know how to prove that if the projector P is self adjoint then P is normal...
  34. T

    Designing a Holographic Projector with Sound and Laser

    Greetings to all. In my first post, I'll present an idea based on acoustical holography. I intend to design a Holographic projector using sound and laser. The hologram is created by reflecting reference laser light on a vibrating diaphragm matrix. The diaphragms are vibrated by means of...
  35. M

    Understanding Projector Matrices: A Math Problem with Complex Numbers

    Consider the matrix A=uv* where u and v lie in C^n (C:complex numbers). Under what condition on u and v is A a projector? I know that a projector is a square matrix P for which P^2= P. Now according to this definition, would that make uv*=Identity. and then u be the inverse of v*? Also...
  36. K

    Finding Oblique Projector P for U, W Subspaces

    Homework Statement Find the oblique projector P so where range(P) = range(U) and range(I-P) = range(W) Homework Equations P^2-P = 0 range(I-P) = null(P) The Attempt at a Solution It seems that U and W are complementary subspaces. According to...
  37. S

    Projector with the greatest projection angle

    A bit about optics. I was wondering what is the film (slide, or motion picture) projector with the widest projection angle. What are the current limitations?
  38. K

    Projector in an arbitrary basis, howto compute?

    Hello! once again I got trouble with Dirac-notation: Homework Statement Given an non-orthonormal basis. Measurement via the projection operator should not give an definit answer, in which state the system was due to the overlap. Geometrical that's clear, but I'm unable to compute that...
  39. Q

    Projector System: Horizontal/Convex Lens for Correct Sequence

    Hi there. If there is to be a back projector system behind a screen (such as a car instrument panel), in order for the information to be displayed in the correct sequence I'm thinking some sort of horizontal/convex lens will need to be used in order to invert the information in the horizontal...
  40. Q

    Calculating Projector Focal Length with SXGA & Screen Dimensions

    Hi. It asks to calculate the focal length range of a projector of square pixel SXGA is from 4 to 12 m from the screen. It gives the diagonal size of the display (in mm) as well as the horizontal size (in m). The thing that am not sure about is how the focal length would be calculated with the...
  41. S

    Projector will not do widescreen from computer

    Here is the weird thing... when my computer is connected to my video projector (epson movie mate 30s) it will do widescreen as it posts but as soon as it gets to windows it locks in a 4:3 ratio. What gives here? I've scanned my video card settings for some sort of toggle but can't find any...
  42. J

    Find the Perfect Projector Lifting Device Design

    I have to find a basic design which includes a device for a raising a slide projector to the proper angle for projection on screen.It may be part of the original projector or an accessory to be attached to existing projectors. If you help me finding it i will be grateful because i could not finf...
  43. check

    Holographic projector? Any idea how it works?

    “Holographic” projector? Any idea how it works? I saw this a couple of years ago. It’s a projector that’s able to display 2D images or simulated 3D video into the air. Here’s the manufacturer’s site: http://www.io2technology.com/ The site has a few really neat videos. Any idea how this is done?
  44. K

    Designing a Basic Overhead Projector: Physics, Calculus, and Mirrors

    For a class, I need to design a basic overhead projector. I know a little bit about optics from an algebra based physics class I took a while back, but I don't remember most of the specifics, such as what kinds of lenses flip objects before and after their focal points. I'm also not sure what...
  45. S

    Projector Optics: Calculate D2, D3 & Net Magnification

    hi, i am in need of help pretty quickly here.i will have to design a projector design using a fresnel lens and the projection lens.i need to find and derive the equations for the lenses and calculate the distances between the lenses and the lens and the screen. this is what i require to have ...
  46. S

    How Do You Calculate Lens Distances and Magnification in a Projector Design?

    hi, i am in need of help pretty quickly here.i will have to design a projector design using a fresnel lens and the projection lens.i need to find and derive the equations for the lenses and calculate the distances between the lenses and the lens and the screen. this is what i require to have...
  47. S

    Optimizing Projector Design: Calculating Lens Distances & Magnification Factors

    hi, i am in need of help pretty quickly here.i will have to design a projector design using a fresnel lens and the projection lens.i need to find and derive the equations for the lenses and calculate the distances between the lenses and the lens and the screen. this is what i require to have...
  48. S

    Projector Optics: Calculate Distances & Find Magnification

    hi, i am in need of help pretty quickly here.i will have to design a projector design using a fresnel lens and the projection lens.i need to find and derive the equations for the lenses and calculate the distances between the lenses and the lens and the screen. this is what i require to have...
  49. S

    Understanding Projectors in Quantum Mechanics: A Mathematical Approach

    I saw some discussions about projectors in some threads. Also, the projector is used in this book to define pure state but did not provide what is a projector. http://www.math.sunysb.edu/~leontak/book.pdf Thru some math. check by assuming TR AP_\psi = (A (\psi) , \psi ) ( In this...
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