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百度 第二个信号:不懂得感恩我们经常看到这样的画面：孩子饭后推开饭碗就去看电视或去玩了，父母则忙碌着收拾碗筷；家里有好吃的东西，父母总是留给孩子品尝，孩子却很少请父母先吃；孩子生病，父母便细致入微地关照，而父母身体不适，孩子却很少问候甚至视而不见。
A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction.
1,026 questions
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Detecting the presence of clear tape on material [closed]
I am trying to find a way to optically detect the presence of clear tape, like Scotch tape and packaging tape, if it's stuck on a piece of paper or other plastic.
The paper the tape is on will not be ...
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2
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Can our eyes see virtual objects?
Note that I am not talking about virtual images.
Can our eyes see virtual objects? If yes, then virtual objects at a specific distance range can be seen or at all distances?
I was learning about using ...
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More than one equivalent lens?
My doubt is: Can there exist multiple equivalent lens for a system of lens seprated by a distanceLet me elaborate it: Consider this diagram
AB is a ray coming from infinity.it bends twice at B and C ...
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How do we calculate the focus of this mirror knowing only the aperture length and the depth? [closed]
I am reading the following problem which is asking that if we know that a concave mirror is 10 inches wide and $\frac{1}{4}$ inch deep in the center (neglecting the thickness of the glass), how far ...
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Why might the stated back focal length (BFL) of a lens differ from the theoretical value?
For the sake of argument, let's consider this negative meniscus lens from ThorLabs, which has a back focal length - the distance between the final surface of the lens and the image plane - specified ...
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What is the magnification of refracting telescope? Also need a better understanding of how it forms a magnified image
I was looking at this diagram and tried calculating the magnification when I realized I'm totally confused by how this actually works.
I'm familiar with the lens equation and "normal" (non-...
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Understanding Telecentric Lenses
An Edmund Optics YouTube video (The Advantages of Telecentricity), contains the diagram shown here. Each object is at the border of the field of view so their images should have the same height. ...
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Why do distant objects appear blurry in magnifying lens but not in spectacles(for farsighted people)?
Assumption for eye glasses:
If we try to see objects from a converging lens(eye glasses) located just in front of the eye, that are farther than the focus(between f and 2f) of the eye glasses, we can ...
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Can a person read with spectacles a book which is located farther than its focus?
I was solving a question but I couldn't understand a concept of it.
A professor reads a greeting card received on his 50th birthday with +2.5 D glasses keeping the card 25 cm away. Ten years later, ...
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Convergent lens in uniform motion [closed]
The question is practically asking what happens to the image of a convergent (convex) lens when it moves (from the left) with a uniform speed (of 5 m/s) and it stops at the focus. This question is ...
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Why doesn't concave mirror form virtual image at infinity when object is placed at focus?
If the object is placed at the focus of the concave mirror (assume very small aperture) we know that the rays will converge at the focus and be parallel to each other. However if we produce these ...
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Modelling the Gaussian Beam Envelope
I am using the complex beam parameter $q=z-z_0+iz_R$, where $z$ is the position on the $z$-axis, $z_0$ is the position of the beam waist, and $z_R$ is the Rayleigh length, to model a Gaussian Beam. I ...
3
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Vision with pupils obstructed at the center
Assume that a person puts special contact lenses on both of his eyes, centered at the pupils, such that each of those contact lenses have an opaque center with diameter 1mm, while the typical pupil ...
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Laser Optics (Triangulation) - Measure thickness of biopsy sample incapsulated in paraffin wax
I'm doing an experiment that involves a 633nm HeNe laser that is collimated and polarised. The objective is to measure the thickness of biopsy samples, that ranges from 1-7 micrometers. I have then ...
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Contradiction on using Huygen's Principle and Snell's Law
Note : I do not need the numerical answer, I just want to know the reason for the contradiction, this question just portrays the scenario of my setup.
The problem I am facing is that, because the rays ...
