Build an Infrared night scope

Posted by Author makecircuits

Build an Infrared night scope

Building a night scope is easy if you have the heart of it which is the image intensifier part. I would recommend using the PVS-5 module which uses `MCP` or Micro Channel Plate technology. This is a U.S. 2nd generation device and is rated at 15,000 times light gain. The resolution is one of the best on the market. It was used in Desert Storm and released to the surplus market about 2 1/2 years ago. However, it can`t be exported out of the U.S. :-( The device can be found for betw1een $350 to $700 depending on the quality you want in terms how new it is or if it used. I will list a couple of vendors at the end.

I have built several of these scopes with and without targeting lasers. The laser will kill your battery in no time and I recommend not using one for normal use as the PVS-5 has excellent response without it (unless you want to scare the crap out of someone in total darkness running around your yard. Just put a laser dot on his forehead and let him figure out where it came from and what is at the end of a 30.30 :-) Anyway, you will need the following:

  • 10" length of 1 3/4" PVC plastic pipe (thinwall)

  • 6" length of 3/4" PVC pipe and end caps (thinwall)

  • 1- 35mm lens with shutter

  • 1- eyepiece (see text)

  • 1- lens mount (I use Minolta lens adaptors and lenses which I pick up at pawn shops dirt cheap)

  • 1- 3/4" washer

  • 1- small spring

  • 1- micro pushbutton switch

  • 1- 3 volt lithium battery (I use the DL123A which Radio Shaft...ahhh..Shack sells for $7.99)

  • 1- tube of silicon rubber (black)

  • And of course, one PVS-5 MCP module

When you receive your module do not pull on the power wires or they will break off inside of the power supply and you now have a several hundred dollar paper weight! Do no handle the front screen if possible. If you do, wipe it clean with a optical lens cleaner. DO NOT tw1EEK THE tw1O POTS IN THE POWER SUPPLY!! These pots adjust the ABC (Automatic Brightness Control) and AGC (Automatic Gain Control). If the pots are set too high, a flashover will occur in the Micro Channel Plates and burn out one or more which means that part of the display is dead. This is noticed by a black spot on the display when the PVS-5 is turned on. With that out of the way, lets continue...

Using fine sandpaper or cheesecloth, smooth out the inside surface of the larger PVC pipe. Test fit the PVS-5 module by sliding it into the PVC pipe. It should fit snug but not tight. Continue sanding until the fit is snug. Next, remove the module and wipe down the inside of the pipe. Spray the inside flat black and let it dry. Once its dry, mount the front lens mount to the PVC pipe and mount the lens. Slide the PVS-5 into the other end and slide it to about 2">from the lens. Focus the lens to infinity and close the shutter all the way so that only a pinhole is open. Point it towards an object 10 feet or better away. Apply 3 volts to the PVS-5 and slide it back and forth until the clearest image can be seen on the display screen. Move the focus on the lens in and out and insure the image remains clear. Secure the PVS-5 into the housing with the silicon rubber. DO NOT GET IT ON THE DISPLAY OR THE FRONT SCREEN! In case you are wondering why you can use the PVS-5 in normal lighting (like a shop or lab) its because of the automatic brightness function. The PVS-5 was designed to eliminate blooming problems with muzzle flash and bright light sources such as gun fire and explosions. Just don`t open the shutter all the way (though it wouldn`t hurt it).

After the silicon rubber is cured, we now start on the `fun` (ugh !) part. This is time consuming (about an hour) and requires a little patience. The eyepiece that I use is a 35mm lens that is `reversed` I.E. you look through the front of it rather than the back. The reason I do this is to eliminate the pincushion effect of the PVS-5`s concave screen. But you can use anything that will magnify the image (even a 8X jeweler`s eye loupe which I used on my first one with `passable` results). Anyway, if you choose to use a 35mm lens like I did, then we have to rework the lens. First unscrew the whole body of the lens. Most will have a small screw stop that won`t allow you to unscrew it completely unless the screw is removed. Once the lens is separated from the shutter and rear optic, clean the grease off of the threads. Next, try a fit test into the PVC housing. If the lens is too tight, grind the threads down until the lens fits snug, but not overly tight. Next, drill a small hole 1/2" from the rear of the PVS-5 at the top to pass the power wires through. Now, put the lens onto the PVC and press it as far in as it will go. Now apply power to the PVS-5. The image will be blurred. Here is the fun part. Remove power and the lens and using a hacksaw or bandsaw, cut 1/2" off of the PVC pipe and try it again. Continue doing this until it `starts` to come into focus. Once it starts to come into focus, saw the PVC in 1/8" sections. Continue until the display is crystal clear. This has to be done whether you use a 35mm lens or not. Whatever you choose, the housing has to be cut to focus the eyepiece correctly. At this point, you need to remove the eyepiece, front lens mount and front lens. Cover the front and rear of the housing with paper and masking tape. Now you can spray paint the housing whatever color you choose. I do mine in flat satin black and they come out great ! Set it aside to dry. After its dry, remove the paper and masking tape. Blow out any particles. Insure that the PVS-5 is secure with silicon rubber. Touch up any scrapes of the flat black paint on the inner surface to eliminate reflections. Clean the front and back of the PVS-5 with optical lens cleaner. Re-assemble the front lens mount and front lens. Insert eyepiece. Drill tw1o 1/16" hole about 1/2" from the rear of the housing on either side of the eyepiece. Secure the eyepiece with tw1o small 2-56 screws. Apply power and insure all is well so far.

Now for the battery holder. This is what the 3/4" PVC pipe and end caps are for. Put an end cap on one end and place it on the main housing so that the front end cap is against the front lens mount. Measure back from the eyepiece about 3/4" and put a mark on the small PVC pipe. Cut the pipe on the mark and place the other end cap on the small pipe. Put the whole thing on the main housing and check the fit. If it is to close to the eyepiece, mark and cut it where it is at a suitable distance. Next, mark exactly where the wires are coming out of the housing on the bottom of the battery holder pipe and drill a small hole there so that the wires go straight into the battery holder. Next, drill a hole for the pushbutton about 1/2" from the end of the front end cap. Remove both caps and set aside for now. Measure 1 1/2" from the rear of the battery holder and place a mark here. Now saw with a hacksaw about 3/4 of the way through the battery holder to form a slot. Grind the washer so it fits flush into the slot (I.E. the round top is even with the round top of the battery holder). Next nip a small slot out of the side of the washer so that the ground wire can pass through it. Insert the washer into the slot and insure it is flush then epoxy it into place by putting a dab of epoxy OPPOSITE the slotted side inside of the battery holder. Next, take a small piece of insulated hookup wire and strip one end. Form a loop that will let a 4-40 screw pass through it and solder the loop. Next place a 4-40 flat head screw into the hole in the center of the washer with the head pointing towards the battery. Place the loop of the wire on the other side and secure it with a 4-40 nut. Solder the other end to one side of the pushbutton switch. Connect the positive wire from the PVS-5 to the other side of the switch. Route the ground wire from the PVS-5 through the slot in the washer and out the back of the housing. Next we make the rear battery connection by using a spring secured into the rear end cap. I used a spring from a `D` cell battery holder and secured it into place with a 2-56 screw and nut. I also soldered the ground wire to the spring after I determined the length so that the cap would just come off and let the battery slide free. But use your ingenuity on this. Install the battery with the positive side pointing towards the front of the scope and put on the rear end cape. Press the button and viola, check for a working scope.

Finally (whew) install the front end cap and secure the battery housing to the main housing with a bead of silicon rubber along both sides of the battery housing. Smooth the silicone down so it looks like it was made like that. Let the silicon dry. Next, paint the housing whatever color you want. Again, I used flat satin black.

DO not point your scope at the sun or other really bright light source. Even though the scope has automatic gain control, a bright IR source could burn the MCP.

One reason for using the lens adaptor was so that a telephoto lens could be used or just a standard 35mm lens. Also, the 35mm eyepiece lens makes it nice for mounting to other devices like a camera (with a 80mm extension) with the threaded lens front. I have built maybe 14 of these and they are great scopes. Far better than the Russian stuff in terms of resolution and clarity