Death of a camera by drowning ! - FLIR VUE, its vulnerabilities and death - Page 1
Forum section: electronics / general

author: Fraser
author_rank: Super Contributor
timestamp: September 20, 2017, 09:37:18 pm
content: Thermal cameras are finding their way onto many different mobile platforms these days. The technology is now small and light enough to be carried by some multi-rotor drone aircraft.Drones come in many forms and with differing capabilities. Some are rated for water landings and can survive submersion ! Such water resistance is important for drone operators who will be operating over water as a motor failure will often lead to a dunking. Sh*t happens !Now if the drone flying platform can survive a water landing, you really need any accessory attached to the drone to be similarly rated. Well you might expect such but that does not mean it is the case. Water immersion survivability is an enhancement not found on all drones or their accessories. You do not fly a non water resistant drone over water, simple. That is unless you are happy to lose it if a motor of system fails.OK to the thermal camera that is the topic of this post......FLIR produce their VUE and VUE Pro series of thermal imaging cameras that may be mounted on remote controlled aerial platforms. The VUE cameras are really just a variant of the TAU 2 core. The TAU and TAU 2 are found inside many thermal cameras but they are protected from the elements by the outer casing that encloses them. In the case of the FLIR VUE, there is no additional water proof casing to protect the bare core chassis. FLIR have elected to not protect the core from water with a case, but rather to use silicone sealant in an attempt to add water tolerance to the chassis. Such a measure is relatively effective against dust and water spray/rain. It does not, however, enable the camera to be submersed in water for any significant length of time. Water will likely find its way in somewhere over time, especially if the camera is submerged at a decent depth where pressure on the casing forces water past seals or sealant.So is the FLIR VUE adequately sealed for use on remote controlled aerial platform ? Well that all depends on where the camera is located and where the aircraft will be flown. If the camera is protected inside a protective housing, it gains protection from expected threats and the vulnerabilities to damage may be reduced to acceptable levels. If the camera is just mounted 'naked' under an aircraft, it is vulnerable to many threats, including impact, dirt, rain and even full submersion in water. If the aircraft is not going to be flown over water, the risk of submersion in such is removed.Can the FLIR VUE survive full submersion in water ? Well from what I can see in the attached images, I suspect that the answer is a definite no. It will drown !The story of this unfortunate FLIR VUE camera is not that unusual.The camera was mounted on the underside of a Quadcopter that was being flown over the sea. There was a systems failure and the drone pitched into the sea resulting in a watery grave. At some point later in time, the drone was recovered from the sea by a diver.The camera was disassembled to investigate its condition. During that disassembly process by persons unknown, the Microbolometer ribbon cable connector was torn off of the PCB. This was likely the result of force being used to separate the chassis parts that were stuck together with silicone sealant. It became obvious after disassembly that the camera had suffered salt water ingress that created corrosion of the PCB's and aluminium chassis parts. The attached pictures were provided in an eBay auction in which the 'owner' was selling the mortal remains of the FLIR VUE.So what failure modes are at work here and is the camera repairable ?1. The type of fluid that contaminates the cameras internal parts often dictates the damage caused. Any fluid acts as an electrolyte and oxidiser around the powered electronics and chassis. Salt water is a very serious contaminant that causes much damage.2. The camera still had power applied to it when it was submerged in salt water.A combination of metals at different potential differences in a salt water electrolyte solution creates electrolytic action. The result of this is the erosion of the power traces, including IC pins ! While the potential difference is present within the cameras electronics electrolytic erosion of powered traces and leads continues. The longer the camera remains powered and soaked in salt water the more damage that will occur.3. The Aluminium chassis of the camera will react with the salt water and oxidise. This is surface oxidisation and so of less concern with regard to repair.4. The camera lens can contain Germanium lens elements. Germanium is a metal and will corrode if submersed in salt water for a period of time. The corrosion causes the anti-reflective coating to lift away from the lens surface, destroying the lens. Such damage cannot be reversed.5. The FFC flag uses an actuator that is mechanical in nature. In the VUE camera, a micro motor is used to operate the flag. Salt water ingress into the motor can cause serious corrosion and destruction of the motor.6. The PCBs used in the VUE camera are a combination of multi layer FR4 and FPC. Electrolytic erosion of the traces and layer interconnects within the PCB's can make the camera beyond repair. Such damage can be invisible from the outside and without camera schematics, faults cannot be traced easily. PCB damage beneath the BGA IC's requires those parts to be removed to inspect and repair the traces.7. The TAU/VUE cameras use high density PCB's that are populated with modern physically very small components. Such components need significant rework skills in order to remove and replace them.8. Poor disassembly trade craft lead to an important Microbolometer connector being ripped off of the PCB. The ripped pads may, or may not, be repairable on this multi layer PCB. Such repair would be quite involved and time consuming.So is this particular FLIR VUE camera repairable ?I rate this as a 50:50 case where the camera might be repairable if there is not too much electrolytic erosion of the PCB's. Sadly the damage is often hidden from view so an accurate assessment is not possible without having the camera on the test bench.I actually bid on the auction purely in order to bring you, dear readers, an insight into the damage that can occur. I was considering the camera a write-off and so limited my bids. Others obviously had more confidence in the condition of the camera as the final bid was, IMHO, excessive considering the failure mode of the camera and visible damage to it. The microbolometer window was unusually contaminated which should not have normally occurred. How did dirt get onto the window I wonder ?It is a pity that I do not have this camera in order to strip it down and show the damage caused to it by powered submersion in salt water, but I am able to produce this post detailing the horrors of such an accident.Is the FLIR VUE ft for purpose ?Yes and No.In normal use in dry conditions the camera appears reasonably well sealed against the elements. It is not, however, adequately sealed for any form of fluid immersion ! Operation of this camera series over water does present the risk of total loss if the airborne platform enters the water, be it fresh or salt. Salt water is far more damaging however.As has already been stated, FLIR basically adapted the standard bare TAU 2 chassis to be carried on an airborne platform. It was not protected by an additional layer of protection inside a well sealed plastic case. The camera and its connections should be protected behind seals made from contoured plastic mouldings and gaskets, not simple Silicone sealant. Such a protective casing need not be expensive or particularly heavy.In short, if you cannot afford to lose it, do not fly a FLIR VUE over water ! As previously stated Sh*t happens !Fraser

author: Fraser
author_rank: Super Contributor
timestamp: September 20, 2017, 09:58:51 pm
content: So what action should you take if your prized thermal camera becomes submerged in water or water ingress is suspected ?In my opinion, this is the procedure you should follow:1. DISCONNECT POWER ! The potential difference of parts within the camera can lead to electrolytic erosion of PCB traces and component leads. The faster the camera is isolated from all power sources, the better the likely outcome.2. Dry the camera casing with a towel.3. Remove the lens and check for water presence within the camera. Shake any free water out of the camera via the lens port.4. DO NOT try the common myths that recommend placing the fluid damaged item in a bowl of rice, or any other food for that matter ! Even pellet form dessicant is not very effective. Do not place your valuable camera in an Oven ! Drying it out does not solve all problems. Contamination is left behind.5. Take the camera to someone qualified to disassemble it as quickly as possible. Oxidation starts as soon as the camera parts are exposed to water, especially salt water. Speed is of the essence, Do not leave the camera sitting for a week hoping it will dry out on its own !6. The camera should be carefully dismantled down to its component parts and inspected for any evidence of fluid ingress. Detailed photographs should be taken of the PCB's and any areas of corrosion that are visible. The PCB's, optical elements and chassis should be washed in appropriate fluids to remove any water and contamination from their surfaces. Compressed air may be used to drive water out from under BGA IC's but the PCB's should really be cleaned in a suitable ultrasonic cleaner. This may sound odd as it gets the PCB's wet, but it is the correct action. The ultrasonic cleaner and its associated electronics cleaning solution will drive fluids and contaminants off of the PCB and from under components mounted on it. This is an essential step if salt water contamination is suspected. Failure to do so will lead to ongoing corrosion in the future due to salt deposits. The PCB's are then rinsed with clean de-ionised water and IPA. They may then be gently dried in a suitably warm environment or with a hair dryer applying gentle heat.7. Any damage to the PCB's may then be addressed with rework techniques. Refer to the original uncleaned PCB photographs for the locations of issues previously identified.8. The camera may be re-assembled once it has been cleaned and repaired. Reapply the required silicone sealant to provide the original level of water and dirt resistance. Take care to not foul the FFC flag with excess sealant.This is a time consuming and expensive process if carried out by a service tech. If you feel confident and are competent to do the work yourself plus, more importantly, have the required equipment for such, then give it a go. Just be very careful during disassembly, photographing of the PCB's and cleaning. Be patient and take your time.The whole situation is best avoided, but then that goes without saying !Fraser

author: lukier
author_rank: Unknown
timestamp: September 20, 2017, 10:01:43 pm
content: I've heard similar story from a friend doing research with drones. Their Flir Tau 2, along with the drone I guess, is now at the bottom of some deep alpine lake, never to be seen again. Some paperwork was required afterwards as well, as this is a controlled item.I wonder how one would waterproof a thermal camera then. Thermal lenses hate water. In the automotive they put a piece of AFAIR germanium glass in front, but isn't it mostly against debris and will corrode with water anyway?

author: Fraser
author_rank: Super Contributor
timestamp: September 20, 2017, 10:17:35 pm
content: Maritime thermal camera use a replaceable Germanium window that lasts a long time before its replacement is needed due to pitting of its surface. The FLIR M series are equipped with such windows. The coating on the window is specially designed to resist salt water attack. Other materials may also be used, such as those used for thermal camera lens protection in industry.It should be stated that occasional water, be it fresh or salt, does not damage Germanium lenses if they are rinsed and dried afterwards. Fire fighting cameras regularly get drenched in water and the camera lens protector just needs to be gently cleaned and dried after the shout.The camera in the auction may have been sat under salt water for some time. The levels of chassis corrosion suggest that to me anyway. This was not a brief submersion in the sea.OT..... divers often search white water rafting rivers below the rapids and find waterproofed Go-Pro cameras that have flown off of boats or crew. Some nice divers return the cameras to their owners, where possible. The Go-Pro is well protected in its water proof case.Fraser

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 20, 2017, 11:26:58 pm
content: Somewhere I read that firefighting cameras use a diamond film for protection. Presumably done using chemical vapour deposition.

author: Fraser
author_rank: Super Contributor
timestamp: September 21, 2017, 08:01:41 am
content: It's called a hard carbon coating.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: September 21, 2017, 10:32:21 am
content: The exposed objective or lens protector is normally coated with an abrasion and scratch resistant coating to prolong its life. Hard Carbon coating is a "diamond like" carbon coating that serves this purpose well.the problems start when a lens gets either scratched, and the coating is breached, or when corrosion starts at the very edge of the lens and starts working its way inwards, lifting the lens coatings as it progresses. The damage can range from 'spider web' tracking through to almost full lifting of the AR coating and 'blisters' of corrosion forming under it. If you try to clean such a badly corroded lens, the AR coating just flakes awayIt should be noted that not all Germanium lenses are protected with Hard Carbon and it is not normally applied to any lenses sitting behind the objective. As such, a lens block may look OK from the outside, but when dismantled the lens elements are suffering lifting and flaking of the relatively soft AR coating due to damp ingress. I have seen this on some really nice lens blocks. Such a pity as the performance of the lenses are severely compromised.Many modern cameras are now using the cheaper to produce molded Chalcogenide Glass IR lenses (i.e GASIR). These do not suffer the same corrosion issues as germanium lenses. Their AR coating can still be damaged though.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: September 21, 2017, 02:57:42 pm
content: DLC by Tydex.....http://www.tydexoptics.com/coatings/dlccoatings/

author: SeanB
author_rank: Super Contributor
timestamp: September 21, 2017, 05:54:00 pm
content: I remember seeing photos of a jet that crashed into the sea, and which was recovered a week later. Basically it was a load of locking wires holding parts together, the magnesium alloy parts that had been there having dissolved into the sea water.

author: Fraser
author_rank: Super Contributor
timestamp: September 21, 2017, 06:32:36 pm
content: I remember my father telling me about the Army Hawker Harrier that landed on the container ship during the Falklands Conflict of 1982. The Army Harrier used Magnesium alloy in its airframe and Pegasus engine. The maritime Sea Harrier dis not contain the magnesium alloy parts... and for good reason.By the time the 'lost' Harrier got to the UK after its long sea journey atop a container ship, it was scrap. It was not ruined by physical impacts from the sea, but rather the salt water and air. All the magnesium alloy parts had rotted away and just left parts that looked moth eaten and like a table doily.The press at the time lauded the efforts of the pilot to save his aircraft. The fact that the airframe and engine were total scrap did not get much publicity. I only know about it because my father worked at Rolls Royce Bristol where the Pegasus engine (or what remained of it) ended up.Salt water can be a vicious oxidising agent.Fraser

author: lukier
author_rank: Unknown
timestamp: September 21, 2017, 07:23:12 pm
content: Quote from: Fraser on September 21, 2017, 06:32:36 pmAnother one ended up in front of the Dyson HQ in Malmesbury.https://aviation-safety.net/wikibase/wiki.php?id=55514

author: Fraser
author_rank: Super Contributor
timestamp: September 21, 2017, 08:00:40 pm
content: LukierMy brother was serving as a Sea King pilot on HMS Invincible around that time. i shall have to ask him if he witnessed this eventFraser

author: Fraser
author_rank: Super Contributor
timestamp: September 21, 2017, 08:13:29 pm
content: Just checked with my father. I got it wrong. The incident with the container ship was not connected with the Falklands Conflict. It was an emergency landing during a 1983 exercise off of Portugal. That Harrier was a Sea Harrier but it suffered serious damage during the landing. It was further damaged by exposure to the elements during its ship born journey. It did not suffer Magnesium alloy damage as the Sea Harrier has none in its construction.The confusion comes from my poor memory from many years ago. My father advised that the non Royal Navy Harriers that flew in the Falklands Conflict were the aircraft that suffered serious salt air damage to the airframe and engine as they were not the Sea Harrier variant They contained magnesium alloy parts which were destroyed by the marine environment in which they flew.Fraser

author: Vipitis
author_rank: Frequent Contributor
timestamp: September 21, 2017, 10:38:05 pm
content: My phone is rated for 5m up to 60 minutes.As far as I understand, the thermal camera has a lens/window made of some silicon alloy

author: 1os
author_rank: Regular Contributor
timestamp: October 07, 2017, 03:02:43 pm
content: Good evening the camera damaged by sea water described by you in this post successfully works.

author: Fraser
author_rank: Super Contributor
timestamp: October 07, 2017, 06:33:20 pm
content: Brilliant news !Can you share what you had to do to revive it please ? I am sure we would all like to hear about it.Were any tracks or IC pins corroded away ? and was the FFC shutter motor OK ? Did that microbolometer PCB Ribbon cable connector re-attachment present any problems with the torn pads ?Much depends upon how long a camera remains submerged but that one did look pretty poorly, especially in the front areas where water ingress was more obvious.What was on the microbolometer window ? I was surprised direct got into that reasonably sealed area.Is the lens suffering any corrosion ?If you are willing to share any pictures of the camera, that would be great. It would complete this thread as I had originally intended to use that drowned camera as a case study in this thread.I am so pleased to hear that you resurrected this Tau from the grave. I really hate it when a decent thermal camera dies !Fraser

author: Chanc3
author_rank: Frequent Contributor
timestamp: October 10, 2017, 09:01:03 pm
content: Looks like 1os has disappeared into the night! I doubt we'll find out more about the revived camera.

author: Fraser
author_rank: Super Contributor
timestamp: October 10, 2017, 10:04:53 pm
content: It seems so.I was pleased, but surprised that it was repaired without some significant work. Hence my interest in how much work was involved.I also know from working on Ex sunk ships radio kit that the salt water damage can continue long after the unit is recovered. Reliability can be an ongoing issue due to corrosion.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: October 24, 2017, 11:27:19 am
content: After a PM to me, I supplied 1os with some guidance on how to connect the Tau core to a PC for access to its configuration. He made comment about it having a very much reduced configuration capability.It would be interesting to hear more about his experiences with the VUE version of the Tau Core.Nothing heard since though. He may be busy with other work.Fraser