Questions tagged [lenses]

A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction.

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Absolute refractive index and power of lens

The power of a lens is the degree by which the lens can bend light, and the absolute refractive index is also the same. What is the difference between them? Is the power of a lens an absolute ...
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Focal length of convex lens and ability of refraction [closed]

Why the convex lens of short focal length has more ability to refract the light?
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Is sign convention necessary in the following equation?

The above diagram is used to derive the following equation which is about the refraction due to the spherical surface. $$\frac{n_2}{v} - \frac{n_1}{u} = \frac {n_2-n_1}{R}$$ The above equation is ...
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Sign convention in refraction at spherical surface

While deriving the formula for refraction at spherical surfaces: $$\frac{n_{2}}{v}-\frac{n_{1}}{u} = \frac{(n_{2}-n_{1})}{R}$$ We use the sign convention that object distance = -u Then while ...
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Why is the size of image increasing as observer moves away from lens?

I was using a convex lens and placed the object at principal axis at a distance from optical center lesser than focal length (between $F_1$ and optical center). Then I started observing the size of ...
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Derivation of Combination of thin lenses in contact: How can object (virtual) be taken at right side of a lens?

My book has the following derivation- Consider two lenses $A$ and $B$ of focal length $f_1$ and $f_2$ placed in contact with each other. Let the object be placed at a point $O$ beyond the focus of ...
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Lens theory, what sets the angle of view in photography?

Is this correct statement that - in photo equipment angle of view forms from dimensions of sensor i.e. if we draw line from top most and bottom most edge of the sensor trough center of the lens we get ...
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Changing the apparent focal distance of an object

I'm not completely confident this is the write SE site to post this on, but it seems like the most relevant one. I want to make an object (with negligible thickness) that is around one to five ...
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Is this given ray diagram for a biconvex lens correct?

Figure shows a biconvex lens of having radius of curvatures as R1 and R2 , in the ray depicted shouldnt the meeting point of the rays be at 2F and the object should be placed at -2F , where F is the ...
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Why bi-telecentric lens works with a finite focal length while it should be afocal system？

I bought a bi-telecentric lens for experiment. From all I've learned before, it accepts only axis-parelle incoming beams and exits the same parelle light, so it should be an afocal system with ...
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Hi everyone, could anyone help me understand how two cylindrical lens can be used to form a laser sheet?

If you look at the below link under 'Laser Sheet', https://www.edmundoptics.com/campaigns/cylinder-lens/ the equation is much easier for a single line generator. I am stuck at the point where I use a ...
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Incoherent imaging through two aberrations

I am doing independent research trying to isolate and solve for distortion of an incoherent target when it passes through a known distortion in the medium and then an unknown distortion in the lens ...
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Why do the eyes of a person wearing glasses not look blurry if almost everything looks blurry when I wear them?

When I wear my mother's (hyperopic) glasses, almost everything appears blurry, (the reason for which was explained in this answer). What I don't understand, is why this doesn't work backwards. ...
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Real or false image formation of a plane mirror and lens [closed]

If an object is placed in-between a plane mirror and a convex lens. Would the image that results from the reflection off the plan mirror into the lens be real. Rough diagram: Plane mirror------Object--...
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Why does magnification work?

I have read the question How do telescopes work as magnifiers? but it doesn't quite address, as far as I can tell, my question. I'm trying to wrap my head around why magnification works rather than ...
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Where is the "infinity" where image of an object kept at focus of a convex lens being formed?

Here the object is AB kept at first focal point F₁, and we see the light rays emerging parallel to each other, meeting at infinity. When the object is kept at focus of a convex lens we say that image ...
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Refractive indices of liquid crystal

Refractive indices of liquid crystal • The birefringence is critical to the optical properties of the liquid crystal and underlies many of the applications of liquid crystals. • By reorienting the ...
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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 ...
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Deriving the thin lens formula from the lens maker formula

I've been studying refraction recently, and I faced some doubts regarding the thin lens approximation. The thin lens formula is given as : $$\frac{1}{v}-\frac{1}{u}=\frac{1}{f}$$ However, I also know ...
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Is it possible to find the magnification of multiple lenses if the object is at infinity?

I understand the ray diagram of three lenses (converging, diverging, converging not stuck together) with an object at infinity, but is it possible to calculate the magnification of the entire system? ...
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Can we see the image of inside of our eye, in front of the eye?

Yesterday, I was sitting with a really bright computer screen (brighter than usual) right in front of me (about 30 cm) and it was like a cubicle (most of the light was blocked from all 3 sides — front,...
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Convex lens in our Eyes

I just learned that our eyes are made up of bi-convex lens, and I know that convex lens are also called converging lens since they converge to form real images that can be caught on a screen. But why ...
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Why objects dont appear closer and smaller to a myopic person and far and larger to hypermetropic person after wearing spects?

I am a myopic person, and wear a concave lens. It is taught to us that lens I wear help to form image on my far point and thus help me to see far object. 1.But we have also learn that concave lens ...
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Optimising the choice of lens for collecting scattered light

I want to figure out the “best” lens for collecting light that is being scattered in air. For simplicity, lets say that the scattered light in the volume of interest is homogenous – i.e. the intensity ...
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Can we use meniscus lens for objective in a telescope?

I am making a telescope, but I had meniscus lens of power +1 (so focal length 1 Metre). I brought it in a optic store since I cannot find the lens of my need in any shop in my city. When I put it in ...
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"Aperture size is much smaller than focal length of the lens"

My theory is limited in this regard so I had a little doubt. I often see it mentioned in the problems that "assume aperture size of lens much smaller than its focal length" what does this ...
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Focal length of Abbe condenser

I am looking for the focal length of a Abbe condenser, i.e. Olympus U-AC2. I cannot find this number at microscope specification sheets nor anywhere else on the internet. Is there a similar way of ...
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How does beam shape (elliptical vs circular/Gaussian) affect interferometry?

I want to understand the importance of beam quality to interferometer systems. This article says the following: A very high (close to diffraction-limited) beam quality, associated with a high spatial ...
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How does the effective focal length work for aspheric lenses? How should I select an aspheric lens?

I am currently looking at aspheric lenses on Thorlabs. I want to use them as a collimation optic for my interferometry experiment. Note that the lenses have a listed EFL (effective focal length). But ...
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Working of liquid lens

we were recently introduced to the liquid lens in school, but i havent quite understood the working of it. I realize that the curvature of the lens is changed by some process, but i dont exactly know ...