Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 23

Thread: Why my blue-ray pointer beam on paper is blue?

  1. #11
    Join Date
    Nov 2007
    Location
    Cairns, Australia
    Posts
    1,896

    Default

    Try it! It doesnt work on all of them, but most of the time it does.

  2. #12
    Join Date
    Feb 2008
    Location
    China
    Posts
    13

    Default

    Quote Originally Posted by thesk8nmidget View Post
    yeah i was playing with mine last night and was actually laying in bed and shining it and when it hit my shower curtain it looks to be STRONG blue color! i wish it was that color all the time!
    I think blue is not so beautiful as violet one. As for the colour itself, I like 405nm better, but it is darker than 473nm one.
    Attached Thumbnails Attached Thumbnails 405 and 473.jpg  


  3. #13
    Join Date
    Jan 2008
    Location
    Stockholm, Sweden
    Posts
    799

    Default

    Quote Originally Posted by liv View Post
    Thank you, Tocket, how can you know that? I think I can try some other place in the nature. As your said, if I point my pen on the detergent, it will look very very blue?
    It's chemistry. It's what I do.

    If the detergent contains optical whitener (only laundry detergents for white clothes do) it will have a very strong blue fluorescence.

    Like Things says, highlighter pens are also fluorescent. They have very efficient dyes, so their fluorescence will be really strong.

    As for fluorescent objects in nature it seems green is the most common color. For example fatty residues are green, but bacteria usually have a red fluorescence. You can also try different flowers.

  4. #14
    Join Date
    Feb 2008
    Location
    China
    Posts
    13

    Question

    Quote Originally Posted by tocket View Post
    It's chemistry. It's what I do.

    If the detergent contains optical whitener (only laundry detergents for white clothes do) it will have a very strong blue fluorescence.

    Like Things says, highlighter pens are also fluorescent. They have very efficient dyes, so their fluorescence will be really strong.

    As for fluorescent objects in nature it seems green is the most common color. For example fatty residues are green, but bacteria usually have a red fluorescence. You can also try different flowers.
    I do not know the fluorescent issue only happen to 405 nm laser, or other lasers at any wavelength? Does it have any request to the inspire wavelength?

  5. #15
    Join Date
    Jan 2008
    Location
    Stockholm, Sweden
    Posts
    799

    Default

    Fluorescence is not limited to UV/violet light, but it is far easier to see at those wavelengths.

    In the process of fluorescence the light loses some energy, thus making it longer in wavelength. This means that light can only make objects glow in a color that is to the right of it in the spectrum. Since violet is the leftmost color it means the whole spectrum is available for fluorescence. But for a green light source only yellow, orange and red are available.

    Another factor that makes fluorescence more obvious for UV/violet light sources is that the light itself at those wavelengths is hard to see. If you use for example green light instead the fluorescence is likely to drown in the reflected green light.

    Fluorescence is not limited to visible light either. One example of particular interest for us is the fluorescence of neodymium(III) in the IR (808nm->1064nm) used in all of our green DPSS lasers.

  6. #16
    Join Date
    Feb 2008
    Location
    China
    Posts
    13

    Default

    Quote Originally Posted by tocket View Post
    Fluorescence is not limited to UV/violet light, but it is far easier to see at those wavelengths.

    In the process of fluorescence the light loses some energy, thus making it longer in wavelength. This means that light can only make objects glow in a color that is to the right of it in the spectrum. Since violet is the leftmost color it means the whole spectrum is available for fluorescence. But for a green light source only yellow, orange and red are available.

    Another factor that makes fluorescence more obvious for UV/violet light sources is that the light itself at those wavelengths is hard to see. If you use for example green light instead the fluorescence is likely to drown in the reflected green light.

    Fluorescence is not limited to visible light either. One example of particular interest for us is the fluorescence of neodymium(III) in the IR (808nm->1064nm) used in all of our green DPSS lasers.
    Thanks, I learn a lot from you. But I thougt the green DPSS laser is stimulated radiation, not the same as fluorescence. The laser needs to be coherent, right?

  7. #17
    Join Date
    Jan 2008
    Location
    Stockholm, Sweden
    Posts
    799

    Default

    They are indeed different things, but also very similar. Fluorescence is spontaneous emission of light and this is what happens in a laser below its lasing threshold. It is undesirable above the lasing threshold, because most of the photons emitted by it are going to waste. However, a small fraction of the photons (originating from the fluorescence) will eventually start to resonate the cavity (there are sufficiently many of them at the lasing threshold). Thus, without the fluorescence there would be no lasing.

    Most people call it fluorescence, but looking at the lifetime of the excited state in Nd:YAG (~200µs) it actually seems closer to phosphorescence. The excited stated in fluorescence only has a lifetime of a few nanoseconds. I'm not sure if the excited state is a triplet state however.

  8. #18
    Join Date
    Feb 2008
    Location
    China
    Posts
    13

    Default

    Quote Originally Posted by tocket View Post
    They are indeed different things, but also very similar. Fluorescence is spontaneous emission of light and this is what happens in a laser below its lasing threshold. It is undesirable above the lasing threshold, because most of the photons emitted by it are going to waste. However, a small fraction of the photons (originating from the fluorescence) will eventually start to resonate the cavity (there are sufficiently many of them at the lasing threshold). Thus, without the fluorescence there would be no lasing.

    Most people call it fluorescence, but looking at the lifetime of the excited state in Nd:YAG (~200µs) it actually seems closer to phosphorescence. The excited stated in fluorescence only has a lifetime of a few nanoseconds. I'm not sure if the excited state is a triplet state however.
    Wow, you are so professional. Can I ask what is your major in? I have never heard of phosphorescence.

  9. #19
    Join Date
    Jan 2008
    Location
    Stockholm, Sweden
    Posts
    799

    Default

    Right now I'm doing my diploma work for a MSc in chemistry and chemical engineering. It is in organic chemistry where I'm synthesizing novel organic dyes for dye-sensitized solar cells. I have only made a couple of new (as in never existed before in the universe) dyes, but it's pretty exciting work.

    Phosphorescence is the process in most "glow in the dark" products. It is much slower than fluorescence. A phosphorescent material can glow for several hours after being excited by a light source.

    I have studied about half a years worth of quantum chemistry, that's where most of this knowledge comes from. Unfortunately quantum chemistry is fairly useless at this time, so I almost consider it to be wasted time.

  10. #20
    Join Date
    Feb 2008
    Location
    China
    Posts
    13

    Default

    You have studied quantum chemistry, organic chemistry, chemistry engineering. You are so gifted at chemistry. My major is optical engineering when I am in college. If some subject with the word of engineering, it will near out daily life and not be very bald, I think. Not like the pure academic ones. But the quantum chemistry makes you acquainted much.

    As for the Dye-sensitized solar cell, I come up with an experiment I had made. the anodic oxidation coating. We used the semiconductor material in electrolyte and add electric current to it, the surface of the semiconductor will be oxidation, and became an even layer film. It is interesting.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •