# Questions tagged [lenses]

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### What is Curvature of eye lens?

I wanted to know what do we mean by "curvature of eye lens", is it the reciprocal of $r$ i.e $c=1/r$ or is it synonymous to radius of curvature of the eye lens. Moreover how does aperture relate to ...
564 views

### General proof of formulas of geometric optics?

In most lf textbooks formulas of geometric optics like lens maker formula and base formula for that are proven (or rather verified from my point of view) by taking specific case (ray diagram) and ...
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### Increase the collection effciency of lens array

In an experiment I am trying to image a phosphor surface on a camera using a 3x zoom lens. The distance of phosphor surface to lens input surface is ~100 mm. The effective focal length of the zoom ...
662 views

### How was microscope-level zoom created by a lens and a water droplet?

It was a rainy night. My glasses were speckled with fresh water droplets. I looked at a distant street light and I was surprised to see cells - a single cell was zoomed in to the level where I could ...
52 views

### Optical bandpass filter at focal point of lens

Optical bandpass filters are designed for a particular angle of incidence (AOI), e.g. see Fig 4 here. However that is for the ray picture of light. Imagine I have a thin bandpass filter positioned ...
213 views

### The sign of a focal length

We know that for converging lens, $f>0$ , for diverging lens, $f<0$. But for many materials I have read so far, it says that: "the focal length of a concave lens is 8 cm." I thought that the ...
94 views

### Given a focal length and an aperture of the telescope, what is its field of view?

While I know FOV of scope is equal to FOV of eyepiece divided by magnification. How can one find FOV given only the focal length and aperture of the telescope?
617 views

### Interpreting Seidel Aberration coefficients

I am trying to model a simple system in Zemax (though I think the question is general and is not limited to Zemax app), but the ray-tracing does not seem to be consistent with the analysis of the ...
868 views

### How to calculate beam spread of a non-point light source via an aspheric lens

I need to determine the angle, or rate of divergence of light from a single aspheric lens when I place a non-point light source (e.g. LED array) at a given distance from the lens which is less than ...
42 views

### Infinity Corrected Microscope vs. $4f$ imaging system

This questions concerns three types of microscope systems and the differences between them. Let me lay out my understanding of these three types of systems. I am imagining imaging with a camera so ...
20 views

### What is the difference between longitudinal chromatic aberration and spherochromatism?

In lens design textbooks, a distinction is often made between longitudinal chromatic aberration and spherochromatism. (See for instance Kingslake's lens design book.) What is simple way to understand ...
17 views

### Polishing Spherical Refracting surface vs Lens

My text book states that When we polish a spherical refracting surface (sphere) it doesn't behave as spherical surface and mirror .It still behaves as spherical surface. The polished side is just ...
24 views

### How far will the imaging be? And is it possible to make it farther?

So currently I'm trying to make a smart glasses, where you have a projector that projects an image onto transparent flat glass, and some of the light will reflect into your eyes (something like the ...
18 views

### How can I focus a laser in the gap between two slits?

I’m trying to focus a green laser in between two slits. The slit width is 0.2mm and gap between the slits is also 0.2mm. I measured the laser’s minimum spot size. It’s elliptical with major and minor ...
38 views

### Parabola black body heating

I'm having trouble figuring out why this following example of shenanigans wouldn't work. If you take a parabolic mirror (say from polished aluminium) with a magnification of M and construct it such ...
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### Finding a Lens System Matrix for a Planar Concave Thick Lens

How can I go about determining the lens system matrix for a planar concave thick lens? I analyzed that a light ray first enters the lens and refracts, then it goes through the lens, and then it ...
157 views

### Location of lens having effective focal length

We know a/c to Gullstrand's equation that the effective focal length of two lenses separated by a distance $d$ is given as $$1/feq=1/f1+1/f2-d/f1f2,$$ but the equation doesn't clarify on the position ...
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### Lens equivalent depth of field

In digital photography, there's the principle of lens equivalency, according to which, when you shoot with a camera which has a smaller sensor than a full frame sensor (which is the same dimension as ...
46 views

### transmission electron microscope beam divergence (limits on resolving power)

I have learnt about TEM recently and have a few questions. I've searched all across the internet but can't find the answer to whether or net electrons in the beam will repel each other thus diverge ...
275 views

### Using Standard Parabolic Mirror With Off Axis Source

I am trying to reflect as much light from a device as possible into a camera located 90* off angle from the light source. Currently I'm using a standard flat mirror placed 45* from the part and camera....