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Thread: What is the difference between 637 nm and 638 nm laser?

  1. #1
    Join Date
    Mar 2015

    Laser Warning What is the difference between 637 nm and 638 nm laser?

    Before we receive the information, or most of us know, means that the good spot, 637nm laser divergence Angle, 638nm means that the light spot and divergent Angle is very poor, why there are such? The reality is that so?
    First of all, from the luminous principle, 637nm and 638nm are the same kind of semiconductor luminescence material, namely they are the same laser, the center of the semiconductor laser wavelength has about 5 nm + - deviation, so 637nm and 638nm from glowing and essentially no difference, in fact, the center wavelength of 637 and 638 is basically consistent, so there is no said 637nm short wavelength is more bright, 638nm because of the long wavelength of 1 nm, brightness.
    But why seems on the surface, 637 is 638 nm light? This is because on the market at present is 637 nm laser tube is single mode laser tube, divergence Angle can be formed through simple light plastic good original spot, brightness is concentrated, in other words, high power density, and the 635 and 638 are multimode, the simple plastic is can't get good divergence Angle of light, the same only add lens plastic case, 638 will be light, divergence Angle of light spot, brightness, through long-distance transmission, a 500 mw power density of 638 as a 170 mw, instead of 637 red light, so it looks as good as 637 bright.
    In light, up to 637 other red and blue light, green light size approximation, the equivalent of almost all the red light on the use, and ordinary 638, spot, blu-ray green big many, only a small part of the red light on the use, the other red waste, both in the periphery of the RGB form large red halo, so close the RGB effect is very bad, especially when using RGB to do animation, look bad.
    Is that 638 did not achieve the 637's as good as the light?
    The answer is no, 638 to achieve 637 like a good spot. If you pay attention to, in a well-known company's parameter list, red light shows the 638 nm and 637 nm, divergence Angle of < 1 mrad.
    We also mentioned above, the luminous nature no differences between 637 and 638, 637 is single mode, 638 was a multimode, 638 through simple optical processing
    Is not achieve the good spot, the difference between 637 and 638 is your ability to do 638 of light well, 637 is very simple, a collimating lens, you could just basic couldn't reflect the company of any optical design and power, 638, on the other hand, have to pass a reasonable design can achieve good spot and divergence Angle, so the stand or fall of 638 spot, poor poor reflects a company's ability of optical design. Radium tzu wei (Laserwave) after long-term exploration and improvement, to find a good solution to the 638 spot, on the premise of guarantee nearby spot, divergence Angle can achieve 638 to 637, because 638 is a multi-mode laser at the same time, the power of a single laser tube is much higher than 637 nm, much less the more than 637 nm tube in light of the complexity, improving the efficiency and save cost, so the price is compared to 637, there is a lot of price advantage, and also to prevent too much lead to more than 637 tube of a light for a long time the laser speckle separate. While at present blu-ray mainly for 445 or 462, green also passed from 532 to 520 nm, blue light, green light is light, in the synthesis of RGB, 638 square spot can maximize with blue and green light overlap, the effect is better than 637 round spot. Therefore, from price, effect, stability, and greatly reduced the difficulty of maintenance, 638 is your better choice.

  2. #2
    Join Date
    Dec 2008


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  3. #3
    Join Date
    Aug 2010
    London or Spain depending on the weather


    Not a bad attempt, I have to admit ....if my Chinese was as good as your English, I would probably consider myself a bit of an expert.

    However, I think that most people on this forum will be unable to understand very much of what you are trying to explain.

    I had to read your post about five times, before I could get the hang of what you were suggesting

    Trying to explain how the module naming process was initiated historically, and how, due to changes in the beam shape and divergence of other coloured modules, this has affected the development of the red modules is difficult, even if you are speaking your own native language, ....... but to attempt to do so in a language which doesn't have the same structure, let alone share the same alphabet is a truly monumental task.

    In essence you appear to have the opinion that the 637nm (single mode) red has a considerably better beam when using simple optics. This you consider most noticeable when projecting graphics over a short distance.

    However,given the development of other colours in multi mode format modules, coupled with the increased sophistication of the optics in multi-mode RED (638nm)modules, these now represents a better overall solution due to the way they are able to match the square beam profiles of most of the multi-mode Green & Blue modules, require less alignment maintenance, and last longer, than over-driven, multiple single-mode diode arrangements!

    If this is indeed what you are trying to say I personally think that you have a very valid argument.! Click image for larger version. 

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    PS. @ Jerry ...Does this mean you think the difference between a Porsche 911 and a Porsche 912 is approx 0.1%
    Last edited by catalanjo; 09-20-2015 at 09:39. Reason: Sympathy for well intentioned Chinese !

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