Recent content by Rap

Hmm - That might be the case. In other words, knowing the SPD of Illuminant C to within an constant, they would only have to measure it at one wavelength to determine that contant, and then could scan the output from the filter to get transmittance. MacAdam's 1942 paper gives loads of detail on...

The image of the text was copied from the CRC Handbook of Chemistry and Physics, 90th Edition (2009-2010). What I want to do is to take MacAdam's raw data from 1942 and convert this into the LMS color space, rather than the XYZ color space as MacAdam did. The LMS color space is based on the...

Hi - thanks sophiecentaur - "Wouldn't 100% represent no filter in place or a filter with zero loss at its maximum? All filter gels have some loss" Yes, but the suggestion was made that the transmittance was somehow referenced to a maximum, which would mean every filter would have one or more...

Forgive me, but it's not sorted out in my mind. Can we define "radiant" to mean energy, or power, or power/cm^2/steradian/hz, i.e. NOT involving the the luminous efficiency function for the human eye V(λ). Can we define "spectral" to mean "as a function of wavelenth". So your definition of...

Thank you everybody for your input, but I still am a bit puzzled by the original problem. I'm trying to find out the meaning of "luminous transmittance" at a particular wavelength when characterizing an optical filter. Here's the quote:

Yes, "white" is a very flexible term. I used to work at a lamp factory, and they had a filter whose transmittance closely matched V(λ), the luminous efficiency function for the human eye. Then they just integrated the radiant power out of the filter over λ to get lumens. Also, I found some old...

Yes, MacAdam does start out by shining a beam of light from "Illuminant A" through two filters producing two colors, which are later mixed and matched. The "white" Illuminant A is just a special tungsten lamp which emits very nearly black body radiation corresponding to 2848 K, at a particular...

Hi sophiecentaur - Thank you so much for posting part of my problem here. I think I can unravel some of it. If you have a beam of light with radiant intensity (eg, power per unit area) J[w] where w is wavelength, then the luminous intensity is J[w]V[w] where V[w] is the luminous efficiency...

Hi sophiecentaur - I am dealing with MacAdam ellipse raw instrument data, which is used to draw a "just noticeable difference" ellipse in the XYZ color space. Roughly speaking, it is an ellipse, inside of which any color is indistinguishable, to the human eye, from the color at the center of the...

Hi sophiecentaur - thank you for your response, but I still need a precise explanation of what that "78%" means when the table says "540 nm, 78%". If I shine a 540 nm monochromatic light beam of *radiant* intensity J thru the filter, will the emitted beam have a radiant intensity of 0.78 J ? By...

I have a table of wavelengths and percentage values. Can someone explain this statement: "The following pages give percentage luminous transmittance at wavelengths 500 to 700 nm. for the standard Illuminant "C" adopted by the CIE." What I need is the ratio of the energy coming out of the...

This has been covered above, but here is a simplified model. If you consider a hypothetical organism that evolves by mutation alone, you have to take into account the variations in the environment. For example, suppose there are two food sources (A and B) available to an organism, and its DNA...

In the words of the hymn "Amazing Grace" (written 1779): When we've been here ten thousand years, Bright, shining as the sun, We've no less days to sing God's praise, Than when we've first begun.

Ok, I'm studying up on K mesons, etc., please let me know if I get this right. The K^0_L particle has an antiparticle and they are distinct. They are continually morphing into each other, but the K^0_L meson is the one that spends a longer time being itself, and when it decays, tends to produce...

I guess it wouldn't make any difference to them alone or us alone. But if there was an upcoming meeting between me and an alien and we shook hands, it would be embarrasing for both of us if we offered what the other considered the "wrong" hand. Not to mention the possible nanosecond of...