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FredFlintstone
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If I had a white light bulb and covered it with the right colour of film (red-ish) will the resulting wavelength be about 700nm?
I believe so...FredFlintstone said:If I had a white light bulb and covered it with the right colour of film (red-ish) will the resulting wavelength be about 700nm?
berkeman said:
Rive said:he answer for the question is actually a 'yes', but if you would ask about the know-how requested in the title instead, then I would say it's better to buy a 700nm LED from a reliable source.
I think he meant discrete 700nm LEDs, not LED Lamp bulbs...pinball1970 said:LEDs in the UK tend to be a certain temp but that can be made up of different spectral power distributions. D65 is is defined as is TL84 I don't think the SDC or CIE have made their mind up about what CCT or spectral distribution of LEDs are, there are lots of them.
berkeman said:I think he meant discrete 700nm LEDs, not LED Lamp bulbs...
The amount of abbreviations required to correctly describe a simple, careless sentence ...pinball1970 said:LEDs in the UK tend to be a certain temp but that can be made up of different spectral power distributions. D65 is is defined as is TL84 I don't think the SDC or CIE have made their mind up about what CCT or spectral distribution of LEDs are, there are lots of them.
Rive said:The amount of abbreviations required to correctly describe a simple, careless sentence ...![]()
I learn something new every day at the PF!pinball1970 said:SDC - society of dyers & colourists
Can you say more about your research? Are you wanting to fine-tune the illumination wavelength(s) in your PhotoBioModulation investigation? Are you wanting to be able to change the illumination wavelength(s) during your investigation? What optical wavelength measurement instrument are you using to document the illumination?FredFlintstone said:Using these with well diffused white light and measuring the wavelength or colour warmth until the right frequency is found.
LEDs are certainly be an option, but I think they might be tricky to source at the right energy output levels (80mW/cm2) needed for photobiomodulation - which is my intended use.
berkeman said:Can you say more about your research? Are you wanting to fine-tune the illumination wavelength(s) in your PhotoBioModulation investigation? Are you wanting to be able to change the illumination wavelength(s) during your investigation? What optical wavelength measurement instrument are you using to document the illumination?
I could not find any details on the products what would guarantee that they are some kind of wavelength filters. More likely they are some kind of color filters instead and produces mixed colors, matching with the approach of @pinball1970.FredFlintstone said:Thank you all for your input. I'm not sure if the easy solution is colour films such as http://shopwl.com/lighting/lighting-gel/
Using these with well diffused white light and measuring the wavelength or colour warmth until the right frequency is found.
How fixed and how wide? Your title says 700nm...FredFlintstone said:This is first-stage research - just fact finding to see what the options and and what the pros and cons will be. My minimum requirement is a fixed wavelength of, say 800nm...
Rive said:I could not find any details on the products what would guarantee that they are some kind of wavelength filters. More likely they are some kind of color filters instead and produces mixed colors, matching with the approach of @pinball1970.
I don't know exactly how biomodulation works, but if it works with mixed colors too, then the it would be OK with a simple LCD monitor.
Somehow I doubt it would work like that, so you might want to search for some wavelength filters (with detailed datasheet, stating the transparency and the wavelength) instead of some basic lighting products![]()
russ_watters said:How fixed and how wide? Your title says 700nm...
Your best bet may be a narrow-band astronomical hydrogen alpha filter, centered at 656 nm.
russ_watters said:How fixed and how wide? Your title says 700nm...
Your best bet may be a narrow-band astronomical hydrogen alpha filter, centered at 656 nm.
Rive said:I have a bad feeling about this project.
Could you please enlighten us if you need a specific color or a specific wavelenght?
The problem with this is that the term usually defines the required area of expertise. That's why there is that confusion at the start of the topic.FredFlintstone said:I think is OK to use the term colour as a rough approximation when they are in the visible spectrum. So if I have a "red-ish" filter this is approximately 700nm.
Thank you. I'll take a closer look at this.Tom.G said:Here is a scan of some common CINE color filters. These happen to peak around 625nm. Many of them are down to 10% out-of-band
I understand the white lamp could be hot but I'm not sure I understand your last sentence about "take too high a percentage"... how does this relate to heat?Ketch22 said:What you are describing as "a specific color of filter" is common practice. Contact a local theatrical supply house or stage equipment retailer. Lighting designers often use Gels to filter the light. The suppliers have swatchbooks very similar to a paint chip book that gives the light spectrum by percentage at a specific Nm that is passed. They use these to design interactions on the stage. It would not be terribly difficult to do a two stage filter. The first gel would filter a color very rich in your desired wavelength. This would also be a composite light that creates a pleasing color. The second filter would then filter the undesirables.
Keep in mind that all of that light that is "filtered" is actually energy that must be absorbed and diffused in the gel. Take too high of a percentage at one time and you can melt your gel.
The right answer to this question depends on the specific requirement. This point really should have been brought up within the first few posts on the thread.Rive said:I have a bad feeling about this project.
Could you please enlighten us if you need a specific color or a specific wavelenght?
I suspect that you do not need a specific wavelength (laser source?) but a particular range of wavelengths. You need to be more specific about your requirement. (I am not just been picky here)FredFlintstone said:feasibility of producing ANY given wavelength
Rive said:The problem with this is that the term usually defines the required area of expertise. That's why there is that confusion at the start of the topic.
For example, here is a spectrum taken from an LCD monitor:
View attachment 223805
(source: http://psy1.psych.arizona.edu/~jforster/dmdx/help/lcd-parameters.html )
In terms of 'color', you can get a decent yellow from this monitor without any problems.
But in terms of wavelength, whatever you do you can never, ever get anything around 600nm, for example.
If you need the wavelength, then you need materials with well defined spectrum in the (existing, available) datasheet and no more 'color' please![]()
You need 80mW/cm2. If your filter eliminates 90% of the incoming light and let's through 10% of it at a specific wavelength (range) then you'll have to deal with 720mW/cm2 dissipation on your filter.FredFlintstone said:I understand the white lamp could be hot but I'm not sure I understand your last sentence about "take too high a percentage"... how does this relate to heat?
You will see yellow, which will exist as the mixture of some red and green, but if your source has no 600nm then it'll be absolutely without any 600nm.FredFlintstone said:I'm trying to understand you, but if you mix light from a red LED and a green LED will you not get yellow light which has a wavelength of approx 600nm, even from an LCD monitor?
sophiecentaur said:The right answer to this question depends on the specific requirement. This point really should have been brought up within the first few posts on the thread.
I suspect that you do not need a specific wavelength (laser source?) but a particular range of wavelengths. You need to be more specific about your requirement. (I am not just been picky here)
I imagine there has been previous work on PhotoBioModulation and those experiments would give an idea of what bandwidth and power flux you need. Have you a good reference for PF to get an idea of what you need? An LED may seem to have a very low power but, once you have passed a 'bright' light source through a narrow filter, you could end up with even less. For high intensity light sources, it's common to use an array of LEDs these days.
Right - got you. Thanks.Rive said:You need 80mW/cm2. If your filter eliminates 90% of the incoming light and let's through 10% of it at a specific wavelength (range) then you'll have to deal with 720mW/cm2 dissipation on your filter.
If your source has high IR radiation then it's even worse. You might need air cooling for the filters and maybe multiple layers of filtering to keep the dissipation on one layer manageable.
Ah, now the lights are coming on, lol. That clears it up for me.You will see yellow, which will exist as the mixture of some red and green, but if your source has no 600nm then it'll be absolutely without any 600nm.
Colors does add, subtract and mix, but wavelengths does not.
If I pick up "warm white" light LED bulb (array) from the shop, and the colour warmth is defined as 3000 kelvin (yellow-ish), am I right to think it will most likely have 600nm wavelength in it?Rive said:You will see yellow, which will exist as the mixture of some red and green, but if your source has no 600nm then it'll be absolutely without any 600nm.
FredFlintstone said:If I pick up "warm white" light LED bulb (array) from the shop, and the colour warmth is defined as 3000 kelvin (yellow-ish), am I right to think it will most likely have 600nm wavelength in it?
FredFlintstone said:If I pick up "warm white" light LED bulb (array) from the shop, and the colour warmth is defined as 3000 kelvin (yellow-ish), am I right to think it will most likely have 600nm wavelength in it?
Most LEDs used for lighting have fairly continuous spectra so there should be some of everything in there. So they are better sources for biological experiments which work on wavelength and not 'colours' (a strictly human quantity).FredFlintstone said:If I pick up "warm white" light LED bulb (array) from the shop, and the colour warmth is defined as 3000 kelvin (yellow-ish), am I right to think it will most likely have 600nm wavelength in it?
Oh yes, but what is the wavelength interval needed? That is very relevant, particularly if you are using a filter to select the bandwidth. You need 10 times the power for a filter that's 1/10 of the bandwidth with the same centre wavelength. If you can't think of a reason to find the bandwidth worth considering then just re read the previous sentence. If it doesn't matter then a cheapo (theatrical lighting?) filter would do. 600nm is 'Orange-ish'. Please be more specific about your requirements or you can't get a useful answer.FredFlintstone said:I gave the power requirement, around 80mW/cm2.
Is this the same thing as frequency? I'm probably looking for 10hz and 40hzsophiecentaur said:Oh yes, but what is the wavelength interval needed?
So if I need 80mW/cm2 in the bandwidth of 810nm to 850nm, with a 10% filter I need 800mW/cm2You need 10 times the power for a filter that's 1/10 of the bandwidth with the same centre wavelength.