Lens Definition and 835 Threads

A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (elements), usually arranged along a common axis. Lenses are made from materials such as glass or plastic, and are ground and polished or molded to a desired shape. A lens can focus light to form an image, unlike a prism, which refracts light without focusing. Devices that similarly focus or disperse waves and radiation other than visible light are also called lenses, such as microwave lenses, electron lenses, acoustic lenses, or explosive lenses.
Lenses are used in various imaging devices like telescopes, binoculars and cameras. They are also used as visual aids in glasses to correct defects of vision such as myopia and hypermetropia.

View More On Wikipedia.org
Recent contents Top users
  1. Toby_phys

    Compound lens separated by a distance

    Homework Statement Homework Equations We will call ##s## the distance of the object from the first lens, ##s'## the distance of the image from the first lens and ##s''## the distance of the image from the second lens. The Gauss's lens equation: $$\frac{1}{s} +\frac{1}{s'}=\frac{1}{f_1}$$...
  2. heavystray

    Invisibility cloaking using 4 lenses

    Hello, So, here's an article about invisibility cloaking http://www.businessinsider.my/how-to-make-a-rochester-invisibility-cloak-2014-9/?r=US&IR=T#ruDbxWBJYWXsXcyW.97 What I don't understand is how's the object between the lenses is cloaked. Is it because the rays are focused to a point...
  3. G

    I Steam punk, Field of view including the eye

    Sorry if I missed the answer in my search. I expect I'm not use the correct terms. I want to design a Galilean/opera glasses style steampunk monical mounted to my reading glasses. I already have a simple lens that I can swing in front of my one eye. When using commercial eyeglass mounted...
  4. R

    Experimentally finding focal length of small biconvex lens?

    I have fabricated a few biconvex lens (12mm diameter) for an experiment and am trying to find their focal lengths. My though is to set up three parallel lasers and find where the beams converge. However, even with the smallest laser diodes I could find, three beams surpass the diameter of the...
  5. T

    Experiment: Measuring the focal length of a converging lens

    Homework Statement You are required to set up a light source, an object grid, a converging lens and a screen so that a quantitative investigation of object and image distances can be performed. Tabulate corresponding object and image distances (p and p' respectively). Also tabulate values of...
  6. tensor0910

    Two lenses: find Di through second lens

    Homework Statement A 1.60 cm tall object is 20.0 cm to the left of a lens with a focal length of 10.0 cm . A second lens with a focal length of 36.0 cm is 44.0 cm to the right of the first lens.Homework Equations 1/f = 1/di + 1/do , hi/ho = di/doThe Attempt at a Solution [/B] calculate...
  7. JulienB

    When is the image produced by a thin lens sharp?

    Homework Statement Hi everybody! Being given three identical thin lenses with the same focal length, I have to determine ##a## (distance object-screen), ##d_a## (distance lens 1-lens2) and ##d_b## (distance lens 2-lens 3) so that a sharp image of the object appears on the screen regardless of...
  8. G

    New Near Point with Corrective Lens?

    Homework Statement So I've calculated the person's corrective lens to need the power of -2.00D now I must find the new near point with the corrective lens on. The initial near point is 15cm and I converted the -2.00D into cm, which is -50cm (I hope). Homework Equations I've used this formula...
  9. G

    Calculate the focal length of a planoconvex lens?

    Homework Statement Calculate the focal length of a planoconvex lens that produces a real image 2.5 times as big as the object if the object is 2.5 cm from the lens? Homework Equations The only one I can think of is 1/f = 1/v + 1/u The Attempt at a Solution [/B] My 'attempt' is 1/f = 1/62.5...
  10. Cocoleia

    Magnification formula for a Galilean telescope

    Homework Statement I am asked to draw the ray diagram for an incident plane wave whose rays are at an angle α with respect to the optical axis of the telescope. I have done this, but I need to find an expression for the angle between the outgoing rays and the optical axis, in terms of f1, f2...
  11. R

    What is the Optical Table Simulator and how can it be used?

    Hi All, My name is Radek Strugalski and I am creator of an Optical Table Simulator, a 2D precise ray tracing engine written in Silverlight 5. It can be used for educational purposes, experimentation or jus fun. It's completely free and so far no plans to spoil it with ads. :) I saw that some...
  12. Deebu R

    Find the Power of a Bi Convex Lens

    Homework Statement If the focal length of the bi convex lens is 25 cm then the power of the lens will be? Since the light striking the lens converges at a point behind the lens will the answer come in positive? Homework Equations Power of lens D= 1/f The Attempt at a Solution D= 1/25= +0.04...
  13. TheCapacitor

    Finding focal point of concave lens using concave and convex

    Homework Statement [/B] I was doing http://stao.ca/VLresources/sci-tie-data/lessons/1400_1499/DivergingLensExperimentDeta.pdf experiment. Let's look at this image: Suppose we get the imaginary object at dv by convergence lens. And this object is like a real object for the concave lens. Then...
  14. E

    A Reversed Spot Diagram: Image & Point Source Effects

    If you have an optics system where you know the spot diagram of the image at on imaging on one plain and projecting onto another. Where you know the spot size for a point source at a given distance from the centre of the field. Now if you reverse the system where the imaging plain now becomes...
  15. Souvik Bhattacharya

    Creating a Holographic Projecting Lens: Ideas and Procedures

    What would it take to create a Holographic projecting lens? Ideas and Procedures are appreciated. Thank you.
  16. A

    Two converging lens, find the final image....

    Homework Statement Homework Equations \frac{1}{p}+\frac{1}{q}=\frac{1}{f} The Attempt at a Solution I already had this typed in word so here is a screen shot: I don't understand why the negative is omitted in the "correct answer" "B." In solving this problem I wanted to proceed in...
  17. S

    Lens aligning various angle of incidence light striking it?

    Assume a flat one square foot vertical plate attached 6 feet up, outside on a wall. Dozens of yards away are various solar reflectors angled to reflect sunlight onto that plate. Problem is, the plate requires to be only struck straight on at a 0 degree angle of incidence. And, all the...
  18. qnach

    Optics/lens/LCD simulation software

    I was told in the industry people use ZeMax ASAP Code V ... to do design. However, I cannot find a trial version of them to practice. Is there anyother sofftware which are free?
  19. Firye Stanly

    Optics of the magnifying glass

    Homework Statement An observer looks at a small object using a magnifying glass with the focal length of 12cm. Distance from his eye to the magnifying glass is 1cm. The shortest distance at which he sees clearly is 25cm and the largest is when the image of the object is in the distance...
  20. Kuzon

    Math in the thin lens equation

    Why isn't 1/f=1/do+1/di just the mathematical equivalent to f=do+di? Can't you raise all terms in the equation to the power of negative 1 to get the latter equation? The maths of reciprocals is confusing me lol.
  21. Artlav

    Ray transformation of a 3d lens?

    Greetings. I'm working on a raytracer, and got stuck with trying to model a lens analytically. Given is a thin lens at position p with the axis n, radius r and a focal distance f, a ray hits it at position p1 going in the direction d. Which way would the ray be going on the other side of the...
  22. A

    Forming an Image with a Convex Lens

    Using a convex lens, can an image be formed at the focal point and if so where would the object have to be from the convex lens?
  23. K

    How can I create an adjustable liquid lens system for windows?

    Hi everyone, I am working on a project on my final project in Product design. The project is about translating digital concept into the analogue world. In my project I am especially interested in the digital “Windows” and am trying to apply the functions and possibilities of digital on to...
  24. A

    At what distance from the lens is the image

    Homework Statement A punctual source of light is in the focal point of a diverging lens. in which distance from the lens is the image. Draw the road of rays. Homework Equations The objects at focal point don't have an image. The Attempt at a Solution http://s32.postimg.org/ociblmif9/image.png...
  25. Alex_Neof

    Determining the focal length of a compound lens

    Homework Statement A biconvex lens, L_1, with focal length of magnitude \left| f_1 \right| = 15 cm is used with a second biconvex lens, L_2, with focal length of magnitude \left| f_2 \right| = 25 cm to form a compound lens system. If the two lenses are placed in mutual contact what is...
  26. terryds

    What Is the Distance Between Two Images Formed by a Lens and Mirror Combination?

    Homework Statement A convex lens which focus point is 10 cm is placed face-to-face with plane/flat mirror in a 20 cm distance. If a candle is placed 5 cm in front of the plane mirror which will get reflected by the mirror and refracted by the lens, so the distance between two first image in...
  27. ezgie

    Effect of Collimated lens on Gauss Beam

    Hello everyone, I am trying to find effect of collimated lens on gaussian beam propagation. Do you know how to solve that? I need any equations ,then going to use them via matlab. Thanks
  28. A

    Calculating Power of Tear Layer in Contact Lens Prescription

    Homework Statement The contact lens prescribed for a mildly farsighted person is 1.25 D, and the person has a near point of 29.0 cm. What is the power in D of the tear layer between the cornea and the lens if the correction is ideal, taking the tear layer into account? Assume that a normal...
  29. C

    Reflections of Light in Contact lens

    It is said that whenever index of refraction varies, there are reflections and it can reach 4% for uncoated surfaces.. how about in thin contact lens used for eyes.. is there also 4% reflection on each surface if they are uncoated?
  30. R

    Parameters of final image formed by lens system

    Homework Statement Compute the following parameters of the final image formed by the lens system shown in the figure below a) position b) size c) nature (Real, Virtual, Upright, Inverted, Etc.) Homework EquationsThe Attempt at a Solution i am kind of lost at where to begin...
  31. kenok1216

    What is the meaning of r in the equation 2t=mλ for dark fingers?

    Homework Statement λ[/B] Homework Equations 2t=mλ for dark fingers The Attempt at a Solution how can i calculate r5001 dark,also ,what is the meaning of r in qusetion(r=5mm),<----- it is not the curvature R of plano-convex lens also it is not r5001 dark,since it will get incorrect answer so...
  32. JohnGaltis

    Double Slit Question with Thin Lens concept

    Homework Statement Consider a double slit experiment with a light source of 540nm. Slit separation is 4mm. A thin glass plate is placed in front of one of the slit,, resulting in each bright fringe moving to the location of the adjacent bright fringe. Find the minimum thickness of the glass...
  33. JohnGaltis

    Multiple Lens System(Objectless and Parallel Rays)

    Homework Statement Consider a telescope composed of two convex lenses, the objective lens and the eyepiece. The objective lens has a focal length of 26cm. Rays parallel to the principle axis enter the telescope through the objective lens and exit the telescope from the eyepiece as parallel...
  34. Titan97

    Covering half of lens with an opaque coating

    Homework Statement hat happens to the image of an object kept before a lens if the upper half of lens is covered by an opaque coating? (The object is kept at a distance $1.25f$ before the lens. Half the object is above the principle axis. $f$ is the focal length of lens). Homework...
  35. Alettix

    Second Law of Thermodynamics - Radiation

    Hello! This is an old problem from the Estonian-Finnish open physics olympiad (2013) and I hope you will be able to lend me some help. 1. Homework Statement Sun-rays are focused with a lens of diameter d = 10 cm and focal length f = 7 cm to a black thin plate. Behind the plate is a mirror...
  36. F

    Thick Lens focal length and surface facing the object

    Hello Forum, In the case of an ideal, thin lens (free from any aberration), it does not matter which face of the lens is facing the object. The results will be identical. What if the lens was an ideal (no aberration) thick less with the H planes, etc...? Would it matter which lens surface is...
  37. S

    Calculating Object Location for Converging Lens with M=-1

    Homework Statement " A converging lens has a focal length f. The object location at magnification equal to -1 is? " Homework Equations m = -S'/S The Attempt at a Solution Here is my solution: M= -1 , S=?? M= -S'/S -1 = -S'/S S= -S'/-1 S=S' And from case 2 that says if an object is placed...
  38. D

    Direction or angle independent image formation in lens

    Is there any way to design a lens or system of lenses where I see the same part of the image, irrespective of direction or angle of view. The light rays can be assumed to be collimated as viewing will be from a distance. Actually- I am looking at focusing on a point or specific area of the...
  39. MaysMrDolphin

    How Do You Calculate the Final Image Position in a Three-Lens System?

    Homework Statement . Three thin lenses, each with a focal length of 40.0 cm, are aligned on a common axis; adjacent lenses are separated by 52.0 cm. Find the position of the image of a small object on the axis, 80.0 cm to the left of the first lens. d=52cm between f=40cm d of object=80cm...
  40. vetgirl1990

    Index of refraction for converging lens

    Homework Statement A thin converging lens has radii of curvature of R1=9cm and R2=-11cm. Assume its focal points F1 and F2 are 5cm from the center of the lens. Determine its index of refraction. Homework Equations Len's Makers equation: 1/f = (n2 - n1 / n1) (1/R1 - 1/R2) The Attempt at a...
  41. Alettix

    Measurement of Focal length with Laser beam

    Homework Statement Hi! I have lately come across some tricky experimental physics tasks, where no solution is given. Some of them involved parts where the focal length of a convex lens had to be measured with a laser. How do you do this? Homework Equations 1/l + 1/d = 1/f (1) where f is the...
  42. R

    Near Point Distance of 25cm, how far should object be?

    Homework Statement A magnifier has a magnification of 9× How far from the lens should an object be held so that its image is seen at the near-point distance of 25 cm? Assume that your eye is immediately behind the lens. Express your answer to two significant figures and include the...
  43. K

    Can you find lens magnification from focal length?

    If you know the focal length of a lens and use the lens equation 1/do + 1/di = 1/f by assigning some arbitrary do and solve for di, can you then find the magnification just from the focal length from -di/do?
  44. R

    What is the speed of sprinter running away from lens?

    Firsts of this is not my problem I don't even take physics but it is my girlfriends. She doesn't know how to get the answer an neither do I. I took some physics but not enough for this. 1. Homework Statement A sports photographer has a 160-mm-focal-length lens on his camera. The photographer...
  45. S

    Image formation by convex lens

    What will happen if look at(or in the direction of) a distant object through a convex lens?
  46. N

    Convex Lens: Image Formation at Infinity & Parallel Rays

    For an object at focal length in front of a convex lens, the image formed will be at infinity and the refracted rays are parallel (refer to the figure). Since our eye lens is convex in nature, why don't it converge these parallel rays so that an image can be formed?
  47. P

    Optical physics and frame of reference....

    What kind of frame of reference do I have to choose when I'm studiyng lens and mirrors? As far as I know you consider positive the direction where the rays are real and negative the one where the rays are virtual, is that always true? Why can't we study a problem of optics choosing a frame of...
  48. 0

    Determining the light intensity in a double convex lens

    Attached is an illustration of an image being demagnified using a double convex lens. I want to determine the intensity of the light (mW/cm2) if I were to put a lux meter at various locations after the convex lens given that the object is at a fixed location. The object is a monochromatic light...
  49. P

    Why Does Light Change Direction When Passing Through a Lens?

    Why does a ray of light change's it's direction as it passes the lens? It's because of the fermat principle? Is because of the index of refraction? (Why there is no index of refraction in 1/p + 1/q = 1/f ?)And if it's because of the index of refraction can we apply snell law? Once the ray passes...
  50. S

    Uncovering the Strength of SEM's Electromagnetic Lenses

    Does anybody happen to know the strength of the electroMAGNETic lenses of a scanning electron microscope? I was thinking of using solenoid coils, which would be enough if I am willing to increase the focal distance, but the lenses on SEM's seem far larger.
Back
Top