Tagged Questions

Physical processes involved when seeing, and comparisons between with other light detection systems. Includes questions about the eye, optical nerve, brain, corrective lenses, etc.

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Colors of the Earth from space, an “average” of particular emitters?

When we're say about 100 km above Earth's ground and look down to it and see the Amazonian region as green, is this green color a sort of "average" of greens from trees from that forest or is the "...
97 views

White LEDs and colour perception

I’m very interested in LED lighting and the different spread of wavelengths that are produced compared to other types (like tungsten). Given that a White LED bulb actually produces 3 different peaks ...
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What equation should I use to determine retinal image size generated by 10 micron DIA input beam?

If I plot the effective focal spot diameter (S) achieved by using the popular expression: S = (4L/pi)(F/D), where L is input beam wavelength, F is the focal length of the lens, and D is the input ...
53 views

Terminology - optical (visual) properties of a structure

I am trying to understand few terminological problems that I encounter. Without knowing keywords it is hard to perform search for literature or publications in the area. The area relates to the ...
91 views

What is the minimal size of the spec of dust I can see with naked eye?

When sun directly shines thru the window - I can see small specs of dusts in the air. All specs have different sizes. Assuming direct sun luminosity is 100kLux, spec is a perfect sphere, reflection ...
135 views

How do I translate from CIE xyY color space to combinations of monochromatic wavelengths

Let's say I have a chromaticity point, on the CIE xyY color space that falls within the real colors. (Like y:0.1, x:0.4 Y:1 -- magenta)[1] I also know that humans can perceive the same color, when ...
18 views

How do I convert cycles per image to cycles per degree of visual angle?

I am working with spatial frequencies of images. I have the power in a range of cycles per image, but how would I got about converting this to cycles per degree of visual angle? I already have the ...
17 views

Broad Spectrum Contact Lenses - How Soon?

Given the amazing advances in metamaterials, how soon will we have the means to view a broad spectrum of electromagnetic radiation (IR through UV) by having it faithfully compressed into the range of ...
25 views

Total uncertainty of multiple stereo camera depth measurements

I have a stereo camera that measures depth for a rectangular area of pixels in a single image. Each depth measurement is obtained independently (this goes back to the stereo matching algorithm used). ...
I have a question involving light absorbance versus absorption. It applies to a stack of different photoreceptor types. I understand the difference between absorbance, which is basically equal to -\...