(Solved) Indigo Alpha Lens focus issue - Page 1
Forum section: electronics / general

author: sam1275
author_rank: Frequent Contributor
timestamp: January 11, 2017, 05:33:59 am
content: Hello, I have a Indigo Alpha:https://www.eevblog.com/forum/thermal-imaging/does-a-swir-camera-sensitive-to-thermal-energy/msg1035318/which comes with a 15 degree lens, the picture will only remain clear on objects between 60-80cm from camera, other will out of focus, I tried my best to rotate the Lens bare handed, but it's very firm and refuse to move, how can I adjust the focus? Thanks.

author: Fraser
author_rank: Super Contributor
timestamp: January 11, 2017, 09:31:00 am
content: Hiya,Two types of lens mount method are common on the Indigo cameras.The lens is either a slide fit, retained by a collar that grips the lens barrel, or a screw fit with fine thread and locking grub screw to prevent movement due to vibration. Both lens mount options were offered for the same camera model.I regret I have no specific information on the ALPHA model that you own. Having looked at your picture though, I believe you have the screw thread mount with grub screw locking. The user manual may provide adjustment detail.A stiff lens screw thread is commonly caused by the following:1. Distortion of the fine screw thread on the lens barrel by an overtightened grub screw.2. Thread locking fluid on the lens threads. Common in industry.3. Old optical grease on threads that has solidified with age (common)4. Drop damage with an impact to the lens front causing damage to lens barrel or threads. Usually obvious from physical marks on lens barrel.Ensure the tiny grub screw is fully released before attempting to adjust lens. I usually remove the grub screw and look into the hole to see the lens barrel thread at the bottom. This confirms a threaded mount and the condition of the threaded section under the grub screw touch point.To release a lens that is stuck due to hardened grease on the threads I often apply a releasing agent/mild lubricant such as IPA or WD40. Once the lens Is removed I clean the threads on both lens and camera with IPA and lubricate with optical thread grease. Vasalene Petrolium Jelly will also work OK. Only a small, amount is needed.There is a weird aspect to your situation though.......In your pictures your cameras lens appears to be fully retracted into the lens mount, as evidenced by the lens barrel finger grip ring being up against the mount ring. That should provide infinity focus ! The distance between the back of the lens and the microbolometer sets the focus as I suspect you know. The greater the distance between the two, the closer the focus point. Your lens to microbolometer distance appears to be too great and needs reducing.In old visible light CCTV cameras it was often possible to set the lens to sensor backfocus distance by moving the actual sensor inside the camera ! Some needed the case to be removed for adjustment whilst others had a screw on the rear or side of the camera case that operated an adjustment mechanism. The mechanism moves the sensor on an internal 'sled' to set the correct distance between the sensor and lens.The Alpha should have a simple focus adjustment but without knowing the history of the camera, it is possible that it was set up for close focus by positioning of the microbolometer inside the case with spacers moving it further away from the lens to achieve very close focus. Production line applications have such a requirement. There is always the possibility that your Alpha is fitted with a close focus lens for its original application ! If such is the case, you may not be able to increase its focus distance without modification.Let us know how you get on with adjusting you cameras focus.Fraser

author: sam1275
author_rank: Frequent Contributor
timestamp: January 11, 2017, 02:38:59 pm
content: Quote from: Fraser on January 11, 2017, 09:31:00 amThank you VERY much Fraser!I feel so lucky to have a specific analyze from a experienced person like youAs shown in photo, there's no locking screw on my camera.I just notice there is a missing screw for the camera case, so it might be disassembled.(It's on the top side, so didn't shown in my photo.)I also noticed there's a very tiny crack on the lens, donno if it's dropped.Both evidence are new to me, I didn't notice them until today...I may try tear it down and see if the sensor can be adjusted.Also, how to check if the Lens is a close focus lens?I'll report back if there's any progress.Thank you again!

author: Fraser
author_rank: Super Contributor
timestamp: January 11, 2017, 03:57:23 pm
content: Hiya,I thought I could see a grub screw hole in the cameras lens mount outer ring in your picture ?? Please look closely for a small hole in the mount flange of the camera and check if it is empty.Fraser

author: sam1275
author_rank: Frequent Contributor
timestamp: January 12, 2017, 12:51:11 am
content: Quote from: Fraser on January 11, 2017, 03:57:23 pmHi Fraser.There are 4 of them, all are empty, and the picture shows 2 of them.I looked into the hole and I can see the bottom end of the lens, I mean the lens seems not fully retracted into the lens mount. But it's stiff anyway.Also, is the locking ring part of the camera?Thank you.Sam

author: sam1275
author_rank: Frequent Contributor
timestamp: January 12, 2017, 10:41:16 am
content: Okay, I disassembled it and have a few findings:*There are 4 boards inside the camera, one on rear, one on front, one on bottom, and one on side, they are plugged together by connectors similar to IDE for laptops, but smaller. There are also some smaller connectors with only 2 pins.*The sensor is made by Boeing companyAnd it have a vacuum tail and a round surface, and a valve-style pin layout.*The shutter is inside the lens mount, not on board.*There's a biggest chip on the bottom, with some material filled the gap to the case, so the tripod mount may also function as a heatsink I guess.So it's a interesting tear down to me, but the sensor is not adjustable, so I reassembled it back and still have to deal with the stiff lens.

author: sam1275
author_rank: Frequent Contributor
timestamp: January 12, 2017, 10:53:34 am
content: Hi Fraser, I don't have WD40 and I'm not sure what's IPA...Can I just drop some machine oil into the holes and try to turn it?Edit: I found it, IPA is iso-propyl alcohol... I don't have it.

author: Fraser
author_rank: Super Contributor
timestamp: January 12, 2017, 02:42:56 pm
content: Hiya,I regret I have no ALPHA specific data on lens removal. It should unscrew BUT it could be a fixed focus lens that is securely mounted to the camera. i.e not intended to be removed ! If it does not turn clockwise or anti clockwise with reasonable effort, do not force it. I presume that you have tried clockwise rotation to see if the lens has a manual focus range of movement ?The beveled mount that sits around the rear of the lens is part of the camera face plate assembly and likely held in place by screws from the inside of the camera face plate. The only way to really be sure how the lens is mounted is to separate the camera front plate from the rest of the camera and look at the inside of the lens barrel fro evidence of parts that should separate, such as threaded sections. Applying excessive rotational force to the lens without knowing the mounting method could end badly so I do not recommend taking a pipe wrench to it ! Hand grip only and then do not go mad twisting it. A clockwise then anti-clockwise twist will normally reveal any movement in the lens mount threads. If none is felt, the lens may be rigid mounted and not intended to unscrew. If the lens does move slightly, you can keep rocking it back and forth to see if it loosens. Adding a small amount of very thin oil is permissible but such should not be allowed to get on the FFC flag or microbolometer window. Only a tiny amount of penetrating oil is often needed to release corroded aluminium lens threads as capillary action spreads it around.Fraser

author: sam1275
author_rank: Frequent Contributor
timestamp: January 12, 2017, 04:47:19 pm
content: Quote from: Fraser on January 12, 2017, 02:42:56 pmThank you very much!Yes I tried both clockwise and counter-clockwise, and I tried my best but the Lens is not moving a bit, although I'm not strong and it's a bit slippery between my hand and the lens. I think oil may not help either...I did remove the front plate during the tear down, but I didn't examine it carefully, I think I may have to disassemble it again.If it's "secure mounted", can I still adjust it somehow?Sam

author: Fraser
author_rank: Super Contributor
timestamp: January 12, 2017, 05:12:31 pm
content: Hi Sam,If you can get some decent pictures of the area inside the rear of the lens and the rear of the camera face plate I may be able to advise further. Sadly I have not been able to find any references to the ALPHA having a user interchangeable lens. It may well be fitted and set at manufacture but anything that can be set, should be able to be 're-set'Even fixed focus lenses need some adjust for correct minimum focus distance.The fact that the lens has no signs of movement suggests that it is securely mounted on the camera. In some lenses, internal lens elements are used to set the focus whilst the front and rear lenses remain static. The adjustment is normally on the lens barrel or via a set screw in the rear of the lens that turns a worm drive rhat in turn moves the mid mounted lens element.If the lens is designed for close up focus only, I regret you would have to consider modifications in order to achieve a longer focus range and there are no guarantees that the lens will perform well at such distances. Hopefully this is not the case though.Bess WishesFraser

author: sam1275
author_rank: Frequent Contributor
timestamp: January 14, 2017, 02:04:23 pm
content: Quote from: Fraser on January 12, 2017, 05:12:31 pmHello Fraser,Photos First:So... it doesn't have any visible screws, I also checked other angles not shown in photos, the inner ring is the same all of the round.And as you can see, there seems to have some glues inside, I can also see a bit on the front lens from outside...So is it fixed and not adjustable? And is it even impossible to remove/change the lens without hard modding?A interesting thing is there are 4 wires to the lens, 2 of them must be the FFC shutter, what about the others? For aperture?Thanks,Sam

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 14, 2017, 02:32:34 pm
content: Quote from: sam1275 on January 14, 2017, 02:04:23 pmCould be the shutter has seperate coils to open & close, or temperature sensing, or anti-condensation heater

author: sam1275
author_rank: Frequent Contributor
timestamp: January 14, 2017, 02:42:43 pm
content: Quote from: mikeselectricstuff on January 14, 2017, 02:32:34 pmThank you.It's unlikely to be separate shutter coil, because they connected to different board.I think the temperature sensing is the most likely...

author: Fraser
author_rank: Super Contributor
timestamp: January 14, 2017, 02:58:19 pm
content: Hi Sam,Thanks for the pictures.The four wires are FFC shutter and lens temperature sensor. It is unusual to find the FFC shutter within the actual lens but the temperature sensor is commonly placed in the lens barrel as the temperature of the Germanium lens element is needed fro radiometric measurements especially in high ambient temperatures.The lens has all the appearance of a fixed focus unit and it is not user changeable. You may recall that Bill commented that his ALPHA has its FFC shutter on the front of the lens ! This suggests that the ALPHA is not untended to have its lens removed or changed. Bill may know whether the lens focus may be changed on his version.I regret that it appears that your ALPHA was specified for a particular task, machine vision is a possibility. Such cameras were used on production lines to monitor the temperature of key components. Such cameras commonly have a limited focus range either variable or fixed for close working.Fraser

author: sam1275
author_rank: Frequent Contributor
timestamp: January 14, 2017, 03:09:30 pm
content: Quote from: Fraser on January 14, 2017, 02:58:19 pmIt's a sad news to me... But is it able to buy a concave lens and put it in front of the camera? I think this would help it focus infinite without modding itself.

author: Fraser
author_rank: Super Contributor
timestamp: January 14, 2017, 03:20:04 pm
content: Hi Sam,Sadly such a converter would be somewhat more complex than just a concave lens. The only simple way to achieve a longer focus distance would be to increase the distance between the lens rear and the microbolometer. Try placing a simple card spacer between the cameras front panel an the camera chassis. some experimentation may reveal what can be achieved by moving the lens further array from the sensor by a few mm.If that approach works, you can make up a more permanent spacer from aluminium or plasticard (model shops sell it in various thicknesses.). Even an old credit card could be pressed into service ! If the lens is fixed focus it should have a decent depth of field. Thsi is quick and easy to try and a lot less complex than changing the optics.Fraser

author: sam1275
author_rank: Frequent Contributor
timestamp: January 14, 2017, 03:33:59 pm
content: Quote from: Fraser on January 14, 2017, 03:20:04 pmThank you very much.But are you sure it will focus further when I INCREASE the distance between the lens and the sensor? As you mentioned previously, it should provide infinite focus if I can screw the lens nearer to the sensor, or am I misunderstood?By the way I still think a simple concave thermal lens would increase the focus distance, because it will just work like a glasses for the near-sighted. Although I didn't ever seen such a lens for thermal camera...I'll do a experiment of the relation between the sensor-lens distance and the focus distance.Sam

author: Fraser
author_rank: Super Contributor
timestamp: January 14, 2017, 04:26:02 pm
content: Ooooops sorry. You are absolutely right. I am so used to modifying stuff for near focus using spacers. Brain fade moment. Apologies.I shall think some more about your lens and comment further if I have any thoughts to share.Please PM me your email address.Fraser

author: Bill W
author_rank: Super Contributor
timestamp: January 15, 2017, 02:16:45 am
content: Quote from: Fraser on January 14, 2017, 02:58:19 pmYes it does focus, and to infinity. It looks pretty similar to this one from memory, I'll have to have a closer look and see if there are any more clues to fix Sam's one.Bill

author: sam1275
author_rank: Frequent Contributor
timestamp: January 15, 2017, 02:26:51 am
content: Quote from: Fraser on January 14, 2017, 04:26:02 pmThank you, no need to apologiesEmail sent.

author: sam1275
author_rank: Frequent Contributor
timestamp: January 15, 2017, 02:28:57 am
content: Quote from: Bill W on January 15, 2017, 02:16:45 amThank you Bill, would you please tell me whether your camera have adjustable focus, and have a removable lens?

author: Bill W
author_rank: Super Contributor
timestamp: January 15, 2017, 01:48:20 pm
content: It is adjustable focus, the lens is essentially fixed, there is no bayonet to switch lenses for example.I'd expect it was calibrated with the lens so exchanging lens types would cause calibration problems.regardsBill

author: sam1275
author_rank: Frequent Contributor
timestamp: January 15, 2017, 02:04:05 pm
content: Quote from: Bill W on January 15, 2017, 01:48:20 pmThank you very much!

author: Bill W
author_rank: Super Contributor
timestamp: January 17, 2017, 01:04:00 am
content: Hi Sam,Had a look and the camera is identical but mine has a different lens (40 FoV). The sensor is in the same position. The lens focusses fine and mounts the same way. I suspect something not right with your lens.regardsBill

author: sam1275
author_rank: Frequent Contributor
timestamp: January 17, 2017, 01:40:07 am
content: Quote from: Bill W on January 17, 2017, 01:04:00 amHi Bill W,Thank you very much. I also remember that my 15 degree FOV lens is also a standard one for Alpha, so it shouldn't be designed as fixed focus, also there's a manual grub on mine but very stiff...Would you please check if your lens also have those suspicious glue trace as mine shown in my pictures? I think there might be someone added those glues to it. Is it possible to use some kind of liquid solution to soften/dissolve/remove those glues?Sam

author: Bill W
author_rank: Super Contributor
timestamp: January 17, 2017, 11:29:26 am
content: Hi Sam.No glue, no grub screws. Through the small side holes I can see the rear of the lens body move past the holes. Could be that if those are holes for grub screws then they would need to be fully removed to allow infinity focusregardsBill

author: Fraser
author_rank: Super Contributor
timestamp: January 17, 2017, 12:17:10 pm
content: Bill has provided what we needed to know. His lens mount is indeed the same as the your recalcitrant lens Sam.If it were my camera I would now take a major, if somewhat brutal, step. I would mount the whole camera in a soft jaw vice ensuring that the lens mount front panel is also gripped tight. I would then wrap the lens barrel in a grippy material like rubber, neoprene or layers of electrical tape. Now the nasty bit. I would us a pipe wrench, yes I know it is an awfully thought, and gently grip the lens barrel via the protective material already applied. I would the rock the barrel back and forth gently before applying more torque in the counter clockwise direction. Some common sense is needed on how much force is applied as you do not want to cause distortion of the aluminium. With luck the lens will free off.For info, the pipe wrench I would use is like a pair of pliers with long handles and a 45 Degree angled head with a nice scolopped jaw to grip pipes. They are not a Stilson wrench !Fraser

author: Bill W
author_rank: Super Contributor
timestamp: January 17, 2017, 01:12:48 pm
content: Just had a close look at one of your images Sam, and there's two odd looking blobs inside the lens which I have arrowed. they do not look right and might be what is locking it up.See attachedregardsBill

author: sam1275
author_rank: Frequent Contributor
timestamp: January 18, 2017, 03:53:48 am
content: Quote from: Bill W on January 17, 2017, 11:29:26 amThank you, mine also have no grub screws, in the previous post I meant the grub it self.I can also see the rear of the lens body through the holes.

author: sam1275
author_rank: Frequent Contributor
timestamp: January 18, 2017, 03:55:52 am
content: Quote from: Fraser on January 17, 2017, 12:17:10 pmThank you, I don't have those tools now, maybe I have to buy them if necessary, BTW, should I really try force it before I deal with the glue?

author: sam1275
author_rank: Frequent Contributor
timestamp: January 18, 2017, 03:59:05 am
content: Quote from: Bill W on January 17, 2017, 01:12:48 pmHi Bill, I rechecked my camera, what you pointed in the picture is not any additional parts, they are just full circles of glues.

author: Fraser
author_rank: Super Contributor
timestamp: January 18, 2017, 11:31:27 am
content: Sam,If the lens is locked by just a small blob of glue it will likely shear under force and release the lens thread. If the glue is all around the circumference of the lens thread then sadly the glue will have a lot of active surface and is unlikely to release the threadYou asked about using suitable solvents to soften the glue.Without knowing the type of glue this will be a case of experimentation. My concerns are as follows...... If the glue was just in one spot, using solvent could cause it to flow into the threads potentially making the situation worse. Some solvents could cause damage to the lens elements if it gets on them. If you go down the solvent path you have to soften the glue and then remove it all before the solvent evaporates and the glue hardens again.In such a case I would normally remove the lens assembly from the camera (including front panel in your case) with the intention to completely strip it down on the bench for cleaning and rebuild. You have the added complication of the FFC shutter/iris assembly. No contaminants should come into contact with the FFC shutter/iris.If possible cut away a small sample of the glue with a sharp hobby knife. You will test the solvents on this sample and so protect the lens assembly from risk during such tests.In terms of potential solvents I always start with the least aggressive. I would see what IPA does first, then white spirit, then methylated spirit followed by acetone. Acetone is pretty aggressive and desolves many plastics. A really aggressive solvent is liquid paint stripper but this should be used with extreme caution as it can damage many things, including you ! It can desolve many glues however. Test your solvents on the small sample of glue in a jar to see what effect, if any, it has upon it. You want the solvent to liquify the sample. I suspect IPA, white spirit and methylated spirits will fail. Acetone has a good chance of dissolving the glue and paint stripper is so aggressive that it will also likely dissolve the glue.I do not envy you doing this task. I would rate it as a pretty miserable situation with not insignificant risk to the lens assembly.Best WishesFraser

author: Bill W
author_rank: Super Contributor
timestamp: January 18, 2017, 12:04:23 pm
content: The only positive is that the lens has a big square flange to fit in a vice, and the part that should move has the grip on it.One other thought, heat ? Again depends on what the glue is and if you can get any out to test.Best of luckBill

author: sam1275
author_rank: Frequent Contributor
timestamp: January 19, 2017, 12:57:01 pm
content: Thank you everyone, I really appreciate your help. I seem to be a little unlucky on this, however I'll try to solve it, I'm not good at chemistry so the solvents Fraser given is a big help. I'll report here if there's any progress.

author: sam1275
author_rank: Frequent Contributor
timestamp: February 20, 2017, 07:16:07 am
content: Hello everyone, I just solved the problem.I bought the tools and ready to do the "brutal" method provided by Fraser, but I thought I should have a last try before it, so I used all my strength to turn the lens bare handed, and it movesSo it turns out that the cause is very simple, the lens was over-tightened on the counter-clock wise, thus locked it to the nearest focus distance, and it just need a strong arm.Sorry that I over-sighted the problem and create such a long mess thread...However I'm glad I use the least harmful method to solve it, especially didn't use chemical, because I took it apart again after I loose the lens, I found the whole thing will rotate together, so I think the glues supposed to glue the individual lens together to a lens module, I would destroy the lens module structure if I unglue them.Thank you everyone for your help!

author: Bill W
author_rank: Super Contributor
timestamp: February 20, 2017, 01:26:41 pm
content: Great news to hear another camera is back from the deadBill

author: Fraser
author_rank: Super Contributor
timestamp: February 20, 2017, 01:36:29 pm
content: Excellent news Sam. Mystery solved 🙂👍

author: sam1275
author_rank: Frequent Contributor
timestamp: February 21, 2017, 02:13:19 am
content: Thank you all.I found a weird thing on my Indigo Alpha, it seems to perform NUC purely based on time, and unaware of temperature.It will NUC 6 times on startup (including the initial one) with 10 seconds interval, then it will do NUC every 2 minutes.Does the Alpha suppose like this?

author: Fraser
author_rank: Super Contributor
timestamp: February 21, 2017, 10:10:01 am
content: When the camera initially starts it carries out a number of FFC events for initial calibration of the image. The microbolometer temperature is being raised to 32C by the TEC during that time. After that the FFC events are fixed in the configuration settings at 120 second intervals. This is considered adequate to correct for nominal pixel drift. IIRC the interval between FDC events may be set in the cameras configuration and it can even be switched off for video recording applications where an FFC event is undesirable. This is certainly the case with the TAU anyway. Take a look at the Alpha user manual, it should detail FFC period and any configuration options. On some cameras an FFC event is triggered when the camera detects temperature changes that need an FFC to ensure a flat field. Not sure about the Alpha though.Fraser

author: sam1275
author_rank: Frequent Contributor
timestamp: February 21, 2017, 12:05:09 pm
content: Hello Fraser.I forgot those cameras have a active temperature stabilization, instead the only temperature monitoring in modern TICs.I re-read the Alpha manual again and it mentioned it have temperature sensors for both FPA and case, but it didn't say FFC will act according to those.I didn't read the manual carefully before, I just found it can operate at 5-30v. Also the digital interface pin out and commands are documented, but I have a few more questions:It says it's RS232 compatible but operate at 3v, it's very strange because RS232 should operate at +-13v, and those 3.3v TTL are inverted RS232 levels, so how can I communicate?Does the settings persistent through power cycles?Thank you.

author: Fraser
author_rank: Super Contributor
timestamp: February 21, 2017, 01:22:48 pm
content: Sam,Go back to the thread where we were identifying your Alpha. In that thread I explained the Communications link and referenced my work on a TAU core that uses the same hardware levels.The Communications are serial and in common RS232 format but the levels are not true RS232. It is UART 'RS232' meaning the levels are 0v and 3v3 with a Space being 0v and Mark being +3v3. Common Maxim UART to true RS232 levels are inverting and produce the required negative Mark and positive Space levels as per the RS232 standard.I used a USB to UART serial board fron China. The board takes its power from the 5V USB supply and provides a 5V and 3v3 output for accessory use. I powered a simple 74HC series inverter chip from the 3v3 and inverted the data inputs and outputs of the USB/UART board. I understand that FTDI USB/UART boards have the option to invert the output via a configuration setting but I was not using FTDI.Hope this helps a little.Fraser

author: sam1275
author_rank: Frequent Contributor
timestamp: February 21, 2017, 02:20:09 pm
content: Quote from: Fraser on February 21, 2017, 01:22:48 pmThank you very much, I actually read your post before, however I was not sure it's the same situation as mine at that time.I used my beaglebone black for serial host, I think maybe I could find a way to make the software invert the level somehow.Would you mind tell me if the settings persist through power cycle?

author: Fraser
author_rank: Super Contributor
timestamp: February 21, 2017, 03:41:43 pm
content: Hi Sam,Yes the settings persist until changed by the configuration software. They are stored in non volatile memory.Fraser

author: sam1275
author_rank: Frequent Contributor
timestamp: February 21, 2017, 03:51:09 pm
content: Quote from: Fraser on February 21, 2017, 03:41:43 pmThank you Fraser!