What is Lenses: Definition and 320 Discussions

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.

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  1. Y

    Optical Help with making my own microscope

    Hi everybody I'm new to the forum, I was looking for somewhere I can find out the make of a microscope hoping this could be the right place. I want to find out so I can hunt down objective lenses.
  2. ilovemycat

    Graphically determining the focal length of a converging lens

    So I have plotted all the given data points on a graph, putting 1/di on the y- axis and 1/do on the x-axis. I have to now find focal length from the graph? I'm not sure how, I'm thinking I have to rearrange the equation 1/f = 1/do + 1/di into y = mx + b form then go from there, but I'm totally...
  3. ab200

    Destroying a Building Using a Lens

    Putting the questionable nature of my professor's problem-writing aside, I found this question pretty confusing. I assumed that 60 m was the focal length, and that R1 was infinity since it is a flat surface. This gives me: 1/60 = (1.5 - 1)[(1/∞) - (1/R2)] This gave me R2 = 30 m, but that isn't...
  4. T

    How do Photochromic lenses work?

    Photochromic lenses are common in glasses, they stay transparent indoor, but get darken when exposed to sunlight. How does it work ?
  5. DragonSpear

    B Shape of Lenses -- Why are they always circular?

    In a magnifying glass, the lenses are always circular. I don't understand why because no matter what shape the lense is, it doesn't deny its physical properties and refraction would still occur, so why are they so consistent on making circular lenses. I predicted that circular lenses may be...
  6. Bluesy

    I Light Refraction, Biconvex Lens, Diagram Help

    I've read that the refraction of light at the boundary of a medium can be described as follows: -a line of connected people marching. one side of the line enters mud, and slows down. This causes the non-mud side to pivot towards the slower side, which then causes the line to change direction...
  7. Aymangh994

    I Using simple lenses to image AFM Probes

    Hello, Using a CCD camera and simple lenses, the probe of the cantilever and its surroundings are to be imaged. Since the cantilever is 50 um wide and some of the surroundings are to be imaged, the optimal image magnification is from 4 to 8. I therefore used a convex lens with a focal length of...
  8. KayT256

    B What does "1 diopter of astigmatism" mean?

    The measurement for astigmatism is diopter. But what does 1 diopter of astigmatism mean? Thanks a lot if you help me figure this out!
  9. bmihalik

    I Using Lenses with Laser Diode Microscope to Reduce Aberrations

    I would like to build a microscope witch can be used with different monochromatic light sources (laser diodes), and this system should has small astigmatic and coma aberration, but keep the chromatic aberration property. Can I use two spherical or ashperical lenses (facing with convex side to...
  10. VVS2000

    I Aberration in Lenses: Formula & Relation Explained

    Is there any formula or a mathematical relation to find aberration in lenses? I read recently that plano concave lens has a negative aberration and plano convex lens is used to correct it. I am not sure what those statements mean. Is there some type of relation that explains these statements or...
  11. VVS2000

    I Spherical aberration in Biconvex and Plano Convex lenses

    I wanted to know about spherical aberration in a biconvex and plano convex lens as I was planning an experiment with them. I was reading about them and came upon the following passage. I don't know whether the given equation is an empirical one or a derived equation. Can anyone help me if you...
  12. photonlz

    How can two cylindrical lenses can be used to form a laser sheet?

    Would you be able to help me figure out the equation to be used at both lenses to get the final light sheet?
  13. Dario56

    I How Do Electromagnetic Lenses Magnify the Image?

    In optical microscope both objective and eyepiece are used to magnify the sample image. Magnification is determined by laws of geometrical optics (intersection of optical beams from the same point of the sample) In electron microscope, electromagnetic lenses are used to magnify the sample...
  14. DhruvSorathiyaPhysic

    I How to make the best collimator using a system of lenses?

    I want to make a collimator lens which can convert the diverging rays from and LCD at finite distance screen into parallel rays. But in order to reduce the aberrations, using system of lens is preferable than using a single lens. Can you suggest the way to create this kind of system please. I...
  15. 1

    Can some liquid hand soaps smudge your eyeglass lenses?

    My control variables are 1. water hardness level, as I live in Florida, and I lodged at a Ritz Carlton also in Florida. I'm not, in any way, affiliated with any corporation herein. I'm not, in any way, affiliated with any corporation herein. 2. my eyeglasses with $700 USD Nikon SeeMax Ultimate...
  16. P

    Problem on thermal radiation and lenses

    I know that the Sun is at a very far distance from the lens, so I assume the rays are parallel and the image is formed at the focus (500mm away from the centre of the lens). How do I calculate the diameter of the image? The hint to solving this problem says that "The angular diameters of...
  17. P

    Question on Optical Systems and Lenses

    Hi everybody and very glad to be here. I am given a small piece of lens which is tightly sealed and there are two lenses at the end and I do not know what is in between. My question is as follow. If I design a small apparatus of object and get the image then will I be able to design a similar...
  18. S

    Instrument using two concave lenses

    Is there maybe instrument using two concave lenses? Tried to google it but found nothing. Thanks
  19. nish95

    Final Image position for a setup with two lenses

    First image is an object for the concave lens so won't +ve direction change from right to left?! In that case, object distance will be -ve (from concave lens towards right side). Any ideas? Solution in the book takes first image's distance to be +ve. See attached ray diagram for clarification...
  20. Ozen

    Concentric Meniscus Lenses Design

    Hello Everyone, I have been working on a lens design that requires a concentric meniscus lens. Initially I was under the impression that r1 should equal r2 for the light to exit at infinity when entering at infinity. However my ray diagram shows different, it shows the light is being bent...
  21. C

    Physics: Converging and Diverging Lenses

    Summary:: I cannot seem to get the answer to the following question. For (a) I am using the formula 1/V= 1/U- 1/F, giving me 7.5cm. I am then adding this to 50cm to get 57.5cm. I then used -1/20-1/57.5-1/v to get **-14.9cm** which is Incorrect. Any help greatly appreciated!
  22. S

    Why Is My Nd:YAG Laser Beam Quality Deteriorating?

    I am working with a Nd:YAG pulsed laser system produced by Continuum back in the early 2000s called the Precision II 8000. We just received the laser from another department at the University and have been setting it up to work unseeded at 532nm. The previous lab team had adjusted the output...
  23. Kaelor

    Inserting thick lenses into a thin lens system and deducing values

    Homework Statement:: Finding the distance between the back surface of the first lens and the front surface of the back lens. Homework Equations:: 1/f = 1/s_o + 1/s_i I have two positive thin lenses that are separated by a distance of 5 cm. The focal lengths of the lenses are F_1 = 10 cm and...
  24. mfb

    A General formula for lenses without spherical abberation

    Publication: Rafael G. González-Acuña and Héctor A. Chaparro-Romo, "General formula for bi-aspheric singlet lens design free of spherical aberration," Appl. Opt. 57, 9341-9345 (2018) Open access preprint: arXiv Given one surface of a lens, how does the other surface has to look like to avoid...
  25. A

    Thin Lenses Problem: Solving for $q=d-p$

    Since ##d=q+p \implies q=d-p## \begin{cases} \frac{1}{I_1}+\frac{1}{d-I_1}=\frac{1}{f}\\ \frac{1}{I_2}+\frac{1}{d-I_2}=\frac{1}{f} \end{cases} Is this correct?
  26. B

    Do magnetic lenses do work on particles flowing through them?

    Do magnetic lenses do work on charged particles flowing through them? Intuitively I would think yes because the magnetic field produced by the electric current in the coil is applying a force on the particles flowing through the lens, so therefore an electric current (the beam of particles to...
  27. J

    Focal length of converging thin lens graphs

    I tried -M=pq = f/(f-p) = f/f - f/p = 1-(f/p) => M+1= -f/p => -Mp-p=f But since it’s the y intercept, p will equal zero and so the focal length will be 0?
  28. G

    Calculate the focal length of the spectacle lens

    Homework Statement A hyperopic eye has a near point of 1.10 m. Calculate the focal length of the spectacle lens required to correct the hyperopia (assume that the near point of the normal eye is 25.0 cm.) Homework Equations 1/f=1/p+1/q The Attempt at a Solution I just used .25 m as p and...
  29. KristinaMr

    Solving for Temp Change of Epoxy Frames for Lenses Insertion

    Homework Statement This is the problem. A pair of eyeglass frames is made of epoxy plastic. At room temperature (20.0°C), the frames have circular lens holes 2.20 cm in radius. To what temperature must the frames be heated if lenses 2.21 cm in radius are to be inserted in them? The average...
  30. K

    What is the power of the lens in diopters?

    Homework Statement It is desired to magnify reading material by a factor of 3.5× when a book is placed 9.5 cm behind a lens. What is the power of the lens in diopters? Homework Equations 1/f = 1/di + 1/do M = -di/do P=1/f The Attempt at a Solution I set equal the magnification to -di/do and...
  31. M

    Finding the Image Location for Two Lenses in Contact

    Homework Statement Two lenses with the focal length of 50 mm are placed tightly. An object is placed 130 mm away from the lenses. Where is the image generated by the lenses? Homework Equations \frac{1}{a}+\frac{1}{b}=\frac{1}{f} L = f_{ocular} + f_{objective} The Attempt at a Solution...
  32. A

    Simulate other lenses with Time of Flight (ToF) camera

    Hello, I have a small project in which I try to use a Time of Flight camera to detect movement in the Field of View. Now the current Field of View is really narrow (about 25° diagonal FoV), which is we I will have to simulate a bigger one. My professor did try to explain to me what changes...
  33. H

    Finding Uniform Focusing in Flexible Fresnel Lenses

    Well this thread title sucks, sorry. << Mentor Note: Title Edited>> :smile: I have a plano convex lens (actually equivalent stack of two fresnels each with focal length 120mm, groove pitch: 0.3mm). If I put a photo behind it at a 45mm distance and view through the lens from a 12mm distane, I...
  34. Michael Sullivan

    ABCD matrix for an optical system of two thick lenses

    Homework Statement I have an object at distance x1 from the first thick lens(convex) then air at distance x2 to the next thick lens(concave) then air of distance x3 to a mirror. I need to build an ABCD matrix representing this. Homework Equations thick lens equation: [ A B ] = [ 1-d/R1...
  35. DylanXO

    Contact Lenses Optics Problem (Two-Parts)

    I believe I have answered the first question correctly (although I am not certain of this). And I'm struggling with grasping how to approach the second part of the question. Any guidance or recommedations on reading material would be greatly appreciated. Homework Statement Contact lenses are...
  36. M

    Physics Lens Problem: Find Object Distance

    Homework Statement An object and its lens-produced real image are 2.4 m apart. Part A If the lens has 55-cm focal length, what are the possible values for the object distance? Express your answer using two significant figures. Homework Equations 1/s+1/s'=1/f s-s'=2.4m The Attempt at a...
  37. S

    Emergent light produced by two lenses

    Homework Statement Two thin lenses are placed 5 cm apart along the same axis and illuminated with a beam of light parallel to that axis, The first lens in the path of the beam is a converging lens of focal length 10 cm whereas the second is a diverging lens of focal length 5 cm. If the second...
  38. M

    Convergent lenses and calculating image position

    Homework Statement Two convergent lens are identical in focal length (f=10cm) and the oobject height (h0) is 3.5 cm. The distance between the two lenses is 30cm and the distance from the object to the first lens is 30cm. -Draw a diagram on the figure and show the image position (di) and size...
  39. W

    Understanding Two Convex Lenses: Ray Diagram and Focal Lengths

    Homework Statement I'm supposed to make a ray diagram of two convex lenses when light initially hits the first lens at parallel rays. When f(total) goes to infinity, the distance between the two lenses = the sum of the focal lengths of each lens. Homework Equations The Attempt at a Solution...
  40. 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...
  41. Scienceislifeforme

    How to Make a Laser That Burns Paper: Tips for Using Multiple Convex Lenses

    I want to make a laser to burn paper so if i use 2 or 3 convex lenses with a laser will it be helpful . Or can i use 1convex then 1 concave and then 1convex to make it
  42. izMuted

    Magnification, when is it negative?

    Homework Statement In magnification, I keep on confusing the signs. From what I understand currently, magnification is positive when the image is erect. An image is only erect when it is a virtual image, therefore virtual images = positive magnification. Vice versa, magnification is negative...
  43. Jamison Lahman

    Aperature, Numerical Aperature and Speed of Lenses

    I think I understand the relationship between the three, but I would like some feedback. I still am fairly unsure about lens speed and is what I'm mostly interested in. From my understanding: Aperture is the total diameter of the lens and numerical aperture is the ratio between the aperture and...
  44. S

    Ultraviolet Laser Beam Shaping With Constraints

    Homework Statement Homework Equations Lens equation 1/f = 1/d_o + 1/d_i Minimum Gaussian beam spot 2*w_0 = ((4 * lamda * F)/(pi * D)) Where: w_0 = beam waist (half beam diameter) lambda = wavelength F = focal length of lens D = diameter of incoming spot Don't forget to match units. Let...
  45. F

    Converging Lenses Homework: Find the Solution

    Homework Statement Homework Equations I'm not sure any, perhaps 1/v + 1/u = 1/f The Attempt at a Solution [/B] I knowp enlargened real images will only be produced if the object distance is lower than the image distance, so that rules out B. Similarly I know that enlargened virtual images...
  46. stevendaryl

    Lenses and Pinholes: What Does "In Focus" Mean? - Comments

    stevendaryl submitted a new PF Insights post Lenses and Pinholes: What Does "In Focus" Mean? Continue reading the Original PF Insights Post.
  47. P

    Plano convex lenses and focal length

    Does the orientation of a plan convex lens affect it's focal lenght? If I put il like in the first example in the photo and makeep the calculation using the lens maker equation I get f positive What happens if I turn the curved face on the right? Using the lens maker equation now the radius...
  48. P

    Why can you solve system of lenses combining the effects?

    In solving a system of lenses you have to work like the second lens doesn't exist and then use the image formed by the first lens and work like the first doesn't exist, how can i demonstrate that doing so is correct? Why is that correct? The path that the rays make is different as is is if the...