Fullscreen HTML5Med Res (??MB)HTML4

Ever wanted to view something really close up – far beyond the capabilities of your eyes? Or perhaps you need to show that extreme close-up to several people at once; maybe even save an image to a disk? This easy-to-build Videoscope – a combination Video Camera and Microscope – will do all this and more! Design by Peter Rosenthal Words by Peter Rosenthal and Ross Tester www.siliconchip.com.au October 2001  11 A number of years ago, SILICON CHIP featured a story about an industrial microscope with an inbuilt camera, capable of displaying images on a monitor. It sold for about twenty thousand dollars or so. And just as we were preparing this article for publication, a press release arrived featuring a similar device from Sony – selling for not much less (see separate panel). Well, this VideoSCope will do a similar sort of job – perhaps not with quite the same finesse as the Sony but similar nevertheless. And even if you have to buy all the bits to make it (unlikely!), you should spend no more than a couple of hundred dollars. Some people may well have most, if not all, of the components gathering dust, just waiting for a use. “So that’s what I can do with that old SLR camera lens I knew was too good to throw away . . .” In fact, this project grew from a Sunday afternoon pulling apart some old scanners, wondering what the lenses could be used for. It has grown into one of the most indispensable workshop instruments. What will it do? Just about anything that you can do with a conventional microscope, you can do with the VideoSCope – and It’s great for checking soldering defects, especially on SMD boards! This shot is at low magnification. A screen-printing stencil, magnified about 3200 times, taken with a web camera instead of the video camera. then some! There are a few limitations which we’ll look at later but suffice to say, you will find so many things to do with it – as I have – you’ll wonder how you got along without it. Here are just a few examples: examining solder joints on PC boards – even surface mount devices (SMDs). Looking for cracks or defects in automotive and other engineering parts. Student projects – examining leaf structures, water, blood, and so on. Even enlarging resistors so their colour codes are immediately obvious to tired old eyes! Another use I have put this to is attaching to machine tools for doing fine work like PC board drilling, fretsaws, and lathe work as in the photo below. I recently had to take a photo of a screen printing stencil and fabric for work and just by rearranging the pipe fittings I was able to gain an effective magnification of 3200 using a 640 x 480 web camera and a standard camera lens. With today’s miniaturisation of circuitry, the VideoSCope is also ideal for circuit inspection and servicing. Included are some pics of ICs taken with this device so you can see the detail and enlargement possible. The photos on the opening page of this article show inside an IC. Not bad, eh? All of the components required are readily available. As we said before, some you may already have. The two items you may not have are the CCD camera module itself and a suitable lens. The camera module can be black and white or colour; any type will do, depending on your possible uses. Colour is nice but obviously more expensive. This design is based on Jaycar’s QC 3483 (thanks to Jaycar for lending me the camera!). One advantage of this camera is that its lens is easily removed and it also comes with a small mounting bracket. You may have another camera on hand or in mind – as long as it fits the space, it has a mounting bracket and its lens is removable, it should be suitable. Alternatively, a web cam would be handy if you want to save and print photos. You simply change a length of pipe to adjust the magnification to suit. Of course, the video camera could also be used for the same purpose in conjunction with a suitable video capture card in your PC. As far as the lens is concerned, almost any lens out of a fax machine, photocopier, scanner, etc could be used but I found the best results from Extreme close-ups of work don’t have to be over the work table. Here the videoscope is swung through 180° to look at the business end of a lathe. Inset is what the camera saw – much finer detail than you could hope to see even with 20/20 vision. This is not a particularly high magnification pic and is somewhat over-exposed – but you get the idea! 12  Silicon Chip www.siliconchip.com.au Lo-magnification mode (above) with the lens and camera both mounted on the underside of the “T” piece; and hi-mag mode (right), with the lens and camera mounted on opposite sides of the “T” piece. Changing modes is very simple. an SLR lens from an old 35mm camera. It has the advantage of adjustable focus and aperture, which most lenses do not. A few plumbing bits are needed – some may be already in your junk box (plumber’s variety!), others you might need to scrounge from a friendly plumber or – perish the thought – buy from a plumber’s supply or hardware store. There is nothing which should cause you any great problems, though. How it works Basically, we are using the camera lens to project an image of the object that we are looking at onto the surface of the CCD element inside the camera. By increasing the distance between the lens and CCD and reducing the distance from the object to the lens, we increase the power of magnification. The camera is a “plumber’s special”, based on 50mm PVC pipe. We can change the distance between lens and CCD by changing the lengths of pipe. We don’t want to make this a treatise on photographics and optics but a couple of salient points might make understanding a little easier. Adjusting the focus of the lens is self-explanatory – we want to achieve the sharpest possible image on the surface of the CCD element. Most lowcost video cameras do not have easily www.siliconchip.com.au adjustable focus; using a 35mm camera lens allows this adjustment. In fact, in the VideoSCope, the focus on the lens is actually a “fine focus” adjustment. Coarse focusing is achieved by physically changing the distance from lens to CCD element. Aperture is something that is less well understood. The aperture control adjusts an “iris”, a series of vanes inside the lens which progressively allows more or less light to pass through the lens. At its maximum (the lowest “f” stop of the lens – a number such as f1.4 or f1.8 is common) the iris is effectively not there – the lens is said to be “wide open”. Conversely, when you adjust the lens to its minimum (the highest “f” stop – a number such as f16 or f22) the iris is closed to a very small opening – in some lenses, just a pinhole. The lens is said to be “stopped down”. Each f-stop on a lens allows half (or double) the light in of the previous stop. Therefore changing a lens from f8 to f16 (two stops) allows just a quarter of the light through. While it might seem that we need to allow as much light through the lens as is available, this is not so. When you adjust the aperture to “wide open”, you minimise the depth of field, that is, the range of distances from the lens which will be in focus. By going the other way and “stopping down” the lens as far as possible, you maximise the depth of field. But as we mentioned, this dramatically limits the amount of light passing through the lens and therefore striking the CCD elements. Most of the time, taking a picture (video or still) is a compromise between the two: depth of field and exposure. If you can increase the amount of light (eg, by illuminating the subject better) you can go for a higher “f” stop and achieve a better depth of field. That’s also what a flash does. On an ordinary camera, increasing the time the shutter is open has the same effect – more time equals more light – but you reach the point where movement (either camera or subject) starts coming into play. On the VideoSCope, there is no shutter. If you are looking at a single-plane object and/or the magnification isn’t too dramatic, depth of field matters less than if you are looking at a 3-D object. Unfortunately, photocopier and scanner lenses are specifically designed to work in one plane and usually have no iris (aperture control) so they are wide open (minimum depth of field) all the time. Again, that’s why the 35mm SLR camera lens is a better option for this project. How it’s made There are many ways which this project could be made and possibly October 2001  13 video SC ope Fig.1: this drawing shows the setup for minimum magnification (maximum magnification would have the camera at the top of the “T”). Use the key below and the colour codes on this diagram to work out how it all goes together. Similar “bits” are similarly coloured: 50mm pipe is all coloured red, sockets (joiners) are all purple, end caps are orange while the T piece is light blue and the elbow (bend) is green). Also note that pipe length “P” and one end of pipe length “K” do not have slots cut in them but all others do. KEY: A B C D E F G H J K L M N P Q R S T U V W X Y Z 14  Silicon Chip 35mm camera lens (see text) End cap for mounting camera 50mm pipe length – various Video Camera (see text) 50mm socket (joiner) Camera mounting plate Retaining screws (2) Cable Gland Camera cable 50mm pipe, 60mm long 50mm "T" piece 50mm pipe, 40mm long Top End Cap 50mm pipe, 70mm long 88° Elbow, female-female 50mm pipe, 150mm long 50mm socket (joiner) 50mm pipe, 300mm long Worm-drive hose clamp, 45mm 50mm (id) flange Self-tapping screws (4) Work table (16mm MDF) Base (16mm MDF) Perspex or Acrylic window www.siliconchip.com.au The first step is to accurately cut the circles in the MDF base and work table, then smooth them with glass paper wrapped in something round and fairly close to the finished size, as shown at right. made smaller but given the fact that we want to fit both a 35mm camera lens and a miniature camera, the “plumber’s special” approach using 50mm PVC pipe seems logical. It’s also relatively cheap, easily obtainable (if you have to buy it) and the material is easy to work with. Another big advantage of this mehtod of construction is that a huge range of focal distances can be obtained, simply by changing pipe lengths. The prototype is shown in the photographs and in Fig.1. We’ll start with the “business end” first, the lens and camera assembly. The lens is mounted on a 50mm end cap. Exact method of mounting depends on the type/brand of lens you use – we cut a hole just large enough to fit the threaded lens through (a friction Here’s how the hose clamp grips the “fingers” cut into the MDF, making it a nice tight (but moveable) fit on the vertical pipe. The centre cut goes all the way to the circle and only needs to be a couple of millimetres fit) and then used some double-sided adhesive to make sure it stayed where we put it. The end cap fits into one of the several lengths of pipe we cut to allow easy changes to the lens-to-CCD-element-distance. We cut 60, 70 and 75mm lengths to swap as required. Camera mounting The camera in question (Jaycar QC 3483) is delightfully simple to mount. It comes with a U-shaped bracket which is secured to a disc of Perspex (or similar) cut to 55mm – just less than the inside diameter of the 50mm pipe joiner (in plumbing parlance properly referred to as a socket). Inside the socket, half way along, is a ridge. When using the socket normally (ie, joining two pipes) this ridge stops the pipes in the right place. Our disc sits on this ridge, with a short length of 50mm pipe slid down onto it to hold it in place. This length of pipe has a cutout to accommodate the power/output wiring from the camera, while the socket itself has a suitable-size hole for the cable gland. We’ll come back to this shortly. The stand Referring again to Fig.1, there is a 300 x 200mm baseboard made from 16mm MDF. Fitted to this is a 50mm flange into which a 300mm length of 50mm PVC pipe is inserted. Slid over this pipe is the work table, a slightly smaller (300 x 150mm) piece of 16mm MDF. A Utilux (worm-drive) clamp at one end tightens fingers cut All of the components of the VideoSCope, including spare lengths to change magnification. Cut out the various lengths of pipe as listed in the parts list. Make sure their ends are nice and parallel and smooth, with four slots cut in most of them to allow easy movement. www.siliconchip.com.au October 2001  15 The camera mounts on a disc of solid material such as Perspex, cut to exactly 55mm diameter so it sits on a ridge inside a 50mm socket (joiner). If those dimensions sound wrong, they’re not: a 50mm socket actually has a 56mm internal diameter! Incidentally, it doesn’t have to be clear, as this one is. into the MDF so it can grip the pipe. The work table has a cut-out window in one end fitted with a piece of clear Perspex or similar material. The reason for the window is so you can illuminate an object from underneath. It could be considered optional but underside illumination is a feature of most “normal” microscopes. (Indeed, it is essential for many observations). On top of the 300mm pipe is a 50mm socket with another length (this time 150mm) of PVC pipe. On top of that pipe is a right-angle elbow or bend, so now the pipe is horizontal. Well, it’s close to 90°. That’s ’cos there is no such thing as a right-angle elbow. They’re actually made at 87°. So in fact our pipe ends up a few degrees off horizontal (three, to be precise!). Fitted to this elbow is another 70mm length of pipe, which in turn fits into the leg of a 50mm “T” piece. Once again, you will note that “T”s are not 90° – the leg is actually at 88°. What this means is that if you fit the “T” the right way around, they nearly cancel each other out and you are left with only one degree of error. Turn it up the other way and the error becomes five degrees – a tad too much! It is the “T” piece that the lens/ camera assembly attaches to. What you should end up with is the lens pointing near enough to straight down to the Perspex window in the work table. You may wonder why we use a “T” instead of an elbow. There are two reasons: one is that two elbows would end up with six degrees of error. While that might be acceptable in some circumstances, it wouldn’t in others. The second reason is even more important: the “T” allows maximum flexibility in lens-to-ccd-element distance. If you want maximum magnification, you want maximum distance: the lens can be fitted under the T while the camera assembly can be fitted above it (obviously with the short bit of pipe and end cap removed first!). None of the joins between the pipes, sockets, elbows and Ts are glued because we need to be able to make changes as required (eg, to adjust magnification or aim the camera elsewhere). Normally, these pipe fittings are a tight friction fit; once in they stay in and removing them takes much effort! To help make them slide in and out of each other easily, each of the pipe lengths has four 15mm slots cut into them, about 2-3mm wide. These are shown in the photos and in Fig.1. ­ Construction Start by cutting out the 16 mm MDF baseboard and work table, taking care with accuracy of the 56mm holes. The hole in the baseboard needs to be a tight fit while the hole in the work table needs to allow the table to slide up and down the pipe. It’s not a loose fit, just comfortable! Get this hole right before cutting the slots, as shown in Fig.2, drawing 3. If you use a jigsaw to cut holes, a narrow scroll saw blade will be required because of the tight radius. Cut slightly under size by following inside of the line, then sand to size by using a piece of sandpaper wrapped around something round. The closer this is The video camera assembly mounted in its holder, shown from below (below) and above (right). Note how the mounting plate sits on the ridge inside the pipe socket (joiner). You can also see how the camera cable comes through the mounting plate and out through a cable gland. Above right is the 60mm length of pipe which clamps the mounting plate (and camera) in position, inside the socket. Note the cut-out to clear the cable gland. 16  Silicon Chip www.siliconchip.com.au Fig. 2: drawings for the various components used in the VideoSCope. Drawing 4 and drawing 5 are same size; rest are to scale. Drawings 1 & 2 use 16mm MDF, 3 uses 50mm pipe, 4 any stiff material to about 3mm thick and 5 can be thin cardboard. www.siliconchip.com.au October 2001  17 Here is the lens-mounting end cap with the cut-out to suit the particular lens we used. On the right of this pic is the lens itself with adhesive foam tabs stuck in place ready to mount on the cap. And here’s what it looks like stuck on. We trimmed the edges of those tabs with a sharp knife. to 56mm, the better. If you do not have a jigsaw you will need to drill a series of holes inside the circle circumference, cut out the remaining material then file and sand to size. If you need some practice, use a scrap of timber first! The square cutout in the table is optional – it only needs to be added if you wish to view transparent objects a cutout as shown in Fig.2 drawing 4. Check that this cutout clears the nut on the cable gland in the socket. Two screws can used to hold this part in place. Cut out the 50mm disc which will be the camera mounting. We used a scrap of Perspex but it can be any rigid material up to about 3mm thick. We drilled one single camera mounting hole right in the middle of the disc; other holes might be needed to suit the bracket supplied with your particular camera. A suitable hole is also drilled through the disc for the cables to pass through. Ours was a lot wider than broad because the cables from this particular camera are triple-width. The camera needs to be mounted square and centrally on this disc, which then fits flush on the ridge inside the socket. For the time being, leave the lens fitted to the camera in place – it protects the CCD element inside. The baffles (as shown in Fig.2, drawing 5) are used to minimise internal reflection in the pipe. When set up for large magnification, the picture may be cloudy and washed out. The baffles prevent this happen-ing.They are made from stiff paper or light card. Around the edge of baffle, cut the tabs as shown in the drawing and fold each tab in opposite directions. Cut the pipe to the lengths nominated in the parts list and clean up the cut edges. Cut the four 3mm wide x 15mm long slots in it at 90° spacing. As previously mentioned, this is to allow easy insertion and, more importantly, removal. by backlighting them. This is filled with a piece of transparent perspex, acrylic or even glass. Pipework First, the camera mount: drill a 16mm hole in the side of one of the sockets (the pipe joiners) 15mm down from the top. Insert the cable gland. Next, cut a 60mm length of pipe with Parts List – VideoSCope 1 35mm SLR lens 1 CCD camera module (Jaycar QC 3483 or equivalent) with regulated 12VDC power supply to suit 1 50mm pipe 300mm long with four 15mm x 3mm slots cut both ends 1 50mm pipe 150mm long with four 15mm x 3mm slots cut both ends 1 50mm pipe 90mm long with four 15mm x 3mm slots cut both ends 1 50mm pipe 75mm long with four 15mm x 3mm slots cut both ends 1 50mm pipe 70mm long with four 15mm x 3mm slots cut both ends 1 50mm pipe 70mm long – no slots 1 50mm pipe 60mm long with four 15mm x 3mm slots cut both ends 1 50mm pipe 60mm long with four 15mm x 3mm slots cut one end and cutout to clear cable gland (see drawing 3) 1 50mm pipe 40mm long with four 15mm x 3mm slots cut both ends 2 50mm DWV end caps 1 50mm DWV flange 1 50mm DWV 88° tee piece 1 50mm DWV 87° elbow 2 50mm DWV socket (pipe joiner) 1 55mm diameter x up to 3mm deep camera mounting plate 1 60mm x 60mm (approximately) Perspex or Acrylic work table window 1 300mm x 200mm x 16mm MDF baseboard 1 200mm x 150mm x 16mm MDF work table 4 rubber feet 1 42mm worm-drive hose clamp 1 12mm cable gland 6 6g 12mm self-tapping screws 1 5mm screw & nut or 2 3mm screws & nuts (to mount camera) Thin card to make two 60mm discs (for baffles) Double sided adhesive tape, pads etc or silicone sealant (to mount lens) 18  Silicon Chip www.siliconchip.com.au PVC. But some form of adhesive may still be required. I used double-sided tape to mount the lens, making sure to get a good bond by cleaning both surfaces. Also make sure there is nowhere for light to get in by wrapping the assembly in black vinyl tape. Another alternative would be to use some silicone sealant as a glue and again lightproof it with black tape. Notes on aperture adjustment. Another view of the lens assembly, looking at the back of the lens. The pin you can see stops the lens down as a shutter fires; you might need to fix this in position on some lenses. Even with these slots, the pipes should be a firm (friction) fit in the sockets, elbows and T piece. While PVC pipe is quite easy to cut with virtually any saw, an angle grinder fitted with a thin blade makes it even easier. It’s also very handy for trueing the end cuts and cutting the slots, too. Painting All internal parts of the pipework, including joiners, T-piece, etc which might be used in the light path between lens and camera need to be painted matt black to stop light reflections. DO NOT paint the fittings (ie, sockets/T/elbows) where the pipes slip in and out – this might make the pipes bind. The baffles also need to be painted, while the wooden base and work table can be sanded and varnished. Mounting the lens The camera lens is mounted in a hole cut in an end-cap, which itself slips over the end of a length of pipe. The idea of this project is to use a lens which is not going to be used on a camera again, so gluing it it place won’t cause any future problems! Because of the differences in various camera lenses, you will have to cut the end cap to suit your own. You only need to cut a hole in the centre as large as the part of the lens that fitted in to the camera. If you use a screw-thread lens (Pentax, etc), if you are very careful with the size of the hole in the end-cap you may be able to use the screw-thread as a self-tapping screw, holding onto the www.siliconchip.com.au Some lenses are fully automatic and only stop down to the set aperture when the picture is taken. Others are semi automatic (with an auto/manual switch) or fully manual. If you have an automatic lens, you will need to work out a way to hold down the lever or pin which stops the iris down. This is important as the auto iris of the camera often wants to set it self too dark or to light. Assembly Insert any piece of pipe through the hole in the baseplate, slide the flange over the pipe and mark the position of the four screws which hold the flange in place. Screw the flange onto the baseboard. Attach four rubber feet in the corners of the underside of the baseboard. If required, cut and glue your piece of Perspex or acrylic into the “window” cut in the work table. Undo the hose clamp completely and place it in position on the slots in the work table. IMPORTANT Before you go any further, clean your work area and the pipe assembles thoroughly for dust and debris – The baffle(s) mount inside the pipe between the lens and CCD camera and help prevent light reflections from washing out” the captured image. They can be made from any stiff material (cardboard, etc) and are painted black both sides. especially the fine dust created when sanding or cutting the PVC pipe. Once you have removed the lens there will be nothing to protect the CCD from collecting dust. Do not touch the surface of the CCD, as removing fingerprints will be difficult, if not impossible. I cannot stress this enough – a microscopic piece of dust will show as a great black spot on your screen. If you do need to clean the CCD, I suggest using a proper lint free lens cleaning cloth. When the viewing aid is not in use make sure you keep the camera section sealed by leaving the lens and end cap on to keep dust out. Fig.1 shows the general arrangement for viewing at minimum magnification. Insert the longest piece of pipe in base, place an elbow on top, add a 65mm length of pipe (horizontal) and add the “T” piece as per drawing. Mounting the CCD camera Unplug the three connecting cables from the camera – most have a tiny plug and socket on them. Remove the two screws which hold the camera to its U-shaped mounting bracket and then secure this bracket to the camera plate (disc). Now replace the camera on the bracket (with the two screws) and place the camera plate assembly into the opposite end of the socket to the hole for the cable gland. Ensure the assembly sits down on the internal ridge. Take it out again for the moment and pass the camera cables through the undone cable gland, then up through the hole in the camera plate and re-connect them to the camera itself. Slide the camera plate assembly back down into the socket, pulling the cable back through the gland as you do. Tighten the gland nut firmly to lock in place. The camera top should be just proud of the top of the socket, allowing you access to the tiny grub screw which keeps the lens in position.You will probably need to remove this grub screw using a jeweller’s screwdriver before screwing the lens off the camera. This lens is not required again. Testing Most of these small cameras require a regulated 12V supply – in fact, you October 2001  19 trying to take photos you may need to change the colour of the light source to suit as some CCD cameras highlight certain light frequencies: fluorescent will bring out blues and incandescent the yellow/red shades. The window in the table is for rear lighting of transparent objects. A piece of paper placed on the base is effective in reflecting light upwards. The closer you get the object to the lens the harder it is to get light in. Also, higher magnification requires more light. If possible, illuminate the spot you are looking at as the excess light can be projected onto the side of the pipe and reflected up to the CCD. The baffles minimise this problem. Insert one at approximately 60 mm up from the lens and one 60 mm down from the camera. And if you have an idle $12,000 . . . OK, we admit it. This TechnoLOOK video microscope from Sony does look a bit more stylish than ours. Not a bit of PVC pipe to be seen! But then again, for around twelve big ones, it would want to look good. Aimed at the high-end education and industrial market, the TechnoLOOK sports a 17cm TFT LCD screen and a magnification of up to 40x. Weighing in at a fairly hefty 6kg, the TechnoLOOK sports a 410,000 pixel CCD and along with its inbuilt LCD, outputs a PAL signal for displaying on an external monitor (video or S-video). Images can be sent from TechnoLOOK to a PC for editing, emailing or incorporation into presentations, magnified to a large-screen display for training, or output as hard copy via a printer. There is a 10x manual zoom; focus and iris adjustment are also fully manual. Zoom, focus, brightness and camera head position are adjusted will void the warranty if you use anything but on some, including the one we used from Jaycar. Connect the supply and connect the video output from the camera to a suitable monitor. Swing the table out of the way and set the focus to about halfway with the aperture wide open (ie, lowest “f” stop). Take an object with plenty of detail and, starting from the base board, move it up towards the lens. You should see it come into focus at some point. Set the table at this height and use the focus ring on the lens to Guide using four simple controls. The unit has an inbuilt laser pointer for positional adjustment and an inbuilt fluorescent lamp provides illumination. For more information, visit the Sony website at: www.sony-cp.com/microscope fine focus. You may also need to adjust the aperture for best picture. Higher magnification To increase magnification, simply add more distance between camera and lens by changing pipe lengths. For maximum distance, connect the lens to the bottom of the “T” piece and the camera assembly to the top. Lighting Ambient lighting should be enough for general use. However, if you are Using a 55mm lens with 40mm between the bottom of the joiner and lens mount, the focus range should be about 24cm to 70cm. A 55mm distance will give you a focus range of about 17cm to 24cm. Remember you can change lengths by swapping pipes or moving the camera above the “T”. Needless to say, this will dramatically change the focus ranges. Experimentation is the best policy. Web cameras Most web cams are too big to fit inside 50mm pipe. Instead, try mounting it in a zippy box. To makes it compatible with this system, you will need to attach the zippy box to a length of 50mm pipe with a hole through the box. When you fit the camera in the box, make sure that its CCD element is in the centre of the pipe and is mounted SC horizontally. PARALLAX BS2-IC BASIC STAMP $112.00 INC GST WE STOCK THE COMPLETE DEVELOPMENT SYSTEM 20  Silicon Chip www.siliconchip.com.au