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Thread: Mirrors... what do I need to know?

  1. #1
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    Default Mirrors... what do I need to know?

    I'm planning to use some mirrors to beef up my hobby show

    I'm thinking about like 8 or more that I mount in different places in my space.
    Will cheep stuff like this work at all? https://www.walmart.ca/en/ip/Zone-Te...RD5X7JDYVDAGAP

    Also, anyone have some inspiration stuff for me?

    I have a single laser projector that I control with LSX.

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    You"re going to want to look for what's called a first surface mirror. Meaning that the mirrored face is on top of the glass. That's a little different from a normal mirror where the mirrored surface is on the back side of the glass. Another words, you don't want the beam to travel through the glass, hit the mirrored surface and bounce off having to travel through the glass again. Little harder to find and a little more expensive but not outrageous.
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    ... if a square size of 40x40mm (or 40x300mm) is enough -- I have some ten mirror-stripes with 30x200 or 40x300 from old kopiers, what are such "first surface" types

    Viktor
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    Thank you

    Great info as usual

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    Default more info

    https://www.google.com/search?sxsrf=...4dUDCAw&uact=5


    Our great friend Fred owns Surplus Shed . (in Pa)
    https://www.surplusshed.com/search.p...surface+mirror


    https://www.surplusshed.com/category/Mirrors.


    I got some square FSMs there made by Kodak. nice size and larger enough to cut smaller, if wanted.
    The cost was reasonable . ATM these are not offered.


    The prob with 'regular or rear surface mirrors is the second and much dimmer 'other' reflection made by the glass. First or front surface mirrors make only one reflection.


    HOWEVER the 'backing' of ordinary mirrors can be removed to reveal the surface and thus making it into a FSM.
    I use paint remover. and go slow and carefully. An old and soft toothbrush worked well for me. Some mirrors are better for this than others. You need to stop once the surface is revealed. Some mirrors and paint removers work better than others.


    Plain glass makes a 'mirror' that passes almost all and reflects very little AND there also exists double sided mirrors-- both sides are the same. These are sometimes found on spinning scanners.

    'Dichros' are also mirrors that pass different wavelengths and reflect others and allow us to combine to make other combos of wavelengths. The 'other' way is knife-edging which puts the lasers very close together but not quite perfectly.

    Two sources of FSMs are found inside old Polaroid cheapie cameras (like ONE-Step) -these are a good size as-is and are 'tombstone' shaped but can be cut IF great care is used--- the glass is very thin. I never pay more than 1$ for these at yard sales and thrift shops etc..... as the 'film' is hard to find ATM. There is also a very nice DC motor inside --great for laser spirograph etc.

    Plastic gears are nice for mounting the mirrors to any motor. One that is a 'tight' fit make a mirror that makes almost a dot or very small circle-- to make a laser circle I use a gear that can be intentionally off- center. If not correctly set up the last mirror might be too small and some of the circle or reflection will be clipped, (not desirable)






    Another source is the HUGE FSM found inside Rear Projected TVs (pretty much no longer being made AND in some the 'mirror' is plastic, I see these big TVs put out for trash all the time-- saw one yesterday BTW.


    DO BE VERY CAREFUL when setting up bounce mirrors-- for sure something to be done while wearing eye protection, BTW these is not easy to set up w/o some help.

    The best FSMs to be used as a laser bounce mirrors are usually close or larger than 6x6 inches which makes for easier set-up. These have two or more adjustments 'places' used for the final fine-turning. I have made my own from two or 3 pieces of Ally plate and some springs and thumb screws

    Another FSM source is found inside flat bed scanners, often long and not very wide--some however are about 3/4 inch wide. These are easy to cut and vary in thickness.

    High quality bounce mirrors from Edmond or Thorlabs are VERY spendy.

    BTW
    I have a large mirror over my bed.
    Printed on one corner is:


    'Objects in mirror are smaller than they appear' JK lol
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    I've managed to track down some amazingly inexpensive first-surface mirror stock by looking for "Kaleidoscope Mirrors". You can often find an 8" by 10" mirror for less than $15. You can cut it with a glass cutter or even just a Dremel tool with an oxide cutting wheel. (You don't need to cut all the way through - just score it and it will break along the score line.) These mirrors are really thin, and they aren't very efficient (92% or so), so I wouldn't use them inside a projector unless I had to. But they're great for bounce mirrors.

    Quote Originally Posted by hakzaw1 View Post
    Our great friend Fred owns Surplus Shed . (in Pa)
    https://www.surplusshed.com/search.p...surface+mirror
    Wait - Fred? Surely this isn't Fred Johnson, formerly from Tampa, FL? As in (formerly) "One Stop Laser Shop" Fred?

    the 'backing' of ordinary mirrors can be removed to reveal the surface and thus making it into a FSM.
    By removing the opaque coating on the back of an ordinary mirror you are exposing the silver reflective layer, so if you use the mirror "backwards", it is now a first surface mirror. But by exposing the silver to air you are allowing it to tarnish over time, which will reduce the reflectivity of the mirror. You're going to need to polish those mirrors every now and then...

    'Objects in mirror are smaller than they appear' JK lol
    ROFL!

    Adam

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