Glare from internal lights


#1

I’ve just been testing the new build and found that when the lights are full on there’s a huge amount of reflected glare from the inside of the tube into the camera lens. It lessens when the camera is tilted up or down, but straight ahead it’s not acceptable. Has anyone else had this issue and are there any solutions?
Andrew


#2

Andrew,

You can improve this substantially by making sure that light is not spilling directly from the lights onto the part of the main tube that is in front of the camera. In the 2.7 kit (which I built) you put some of the black mesh sleeve on either side of the camera, but it does not block all of the light. I have since put some black foam (the type that IC’s and transistors are shipped in) in a square around the camera and that makes a big difference. It does not cure it though. For a complete cure you need external lights that sit out side the tube. I am in the processing of building some.

Note that this is only an issue in really dark water. You can do and see a lot with the stock setup.

Chris


#3

Hello Chris, this sounds very interesting. Could you upload an picture of your foam around the camera?

Best reagrds

Dominique


External Lights and our second trip to the Dater Mine
#4

You can see the foam in this picture. It is around the camera, top, bottom and on the sides:


#5

Thank you for the picture Chris ! Does the Foam Touches the Acryl ?


#6

Yes the foam touches the acrylic. It was cut to be slightly rounded (the shape of the tube) but is squashes down to fit. It is mounted with double sided sticky tape.


#7

I’ve done mine and it seemed to work well.


#8

Another good way to eliminate glare is to make the external light modification. With the right external light placement you can experiment with a variety of conditions and I have found it eliminates glare completely.


#9

I’ve 3D printed a set of glare shields for the internal LED’s. You can find the files here: http://www.thingiverse.com/thing:1335930

I like the foam idea above, but I was thinking it would be good to attack the problem close to the source, as the reflection bounces around so much inside the tube. The blue light board PCB is being reflected in the image (the second photo with the glare shields installed). You can see the circular cutouts on both sides. I’ll definitely try some black felt on the PCB to address that. I left the outer profile at the O.D. of the end plates of the electronics frame, which leaves a bit less than 1 mm clearance to the I.D. of the 4" tube (assuming concentricity). Maybe I’ll add some black foam gaskets.

It definitely helped, but it could be better…


#10

Here is further improvement with a black felt face mask (:sunglasses:) on the light board to get rid of the reflections from the shiny blue PCB:

Sorry, it’s daytime, so the hall isn’t dark. Had to go in the closet. These are all with the internal lights full bright. The first photo is with a paper and black Sharpie version (notable remaining glare in the lower left corner):

This is using the felt version pictured above (you can see traces of the glare in the lower corners, but it’s getting pretty good!):

I’ll check back in if tests in the dark pool produce any really different results, and i’ll post the drawing of the face mask on the Thingiverse page in case anyone really wants to vaporize polyester felt.


#11

The black felt face mask is a great idea. I made mine the old occasioned way; with a exact o knife and lots of time. I don’t have the means to vaporize polyester in an organized fashion.


#12

Nice! I’m definitely a fan of cutting with a knife! I was thinking I would compare some fabrics so I bought two polyester felts, some cotton flannel, and considered some velvet, then balked at the price. So having three to compare I figured it was worth making a drawing and using the laser. My sort of sciencey comparison favored this polyester felt, but I’m not convinced there isn’t something better out there. I know they use a black velvet-ish tape at the edge of projection screens to kill the edges of the projected image. Maybe I’ll try that.

I’d be happy to cut a bunch if there’s a demand for it, and a favored material. So far the felt is awesome, with zero detectable glare in dark pool water…


#13

Hi there. If you want to drive yourself crazy, try Googling Nextel Black Velvet paint. It used to be made by 3M and was what they coated the inside of optical instruments with. I used it on solar panels in the 80s. It’s as near totally black as you can get. I believe someone still makes it but I’ve gone round in a few circles with Google.
Andrew


#14

I have done some experiments as well with glare reduction for the internal lights.

I went the foam route in order to try to block the lights from the camera.

Front view of the ROV

0.25" thick foam that was used

ROV video after foam is in place

Here is the DXF file that I used to laser cut the foam.
2.8 Light Board Blinder for Forum.dxf.zip (63.2 KB)

Known Issues

  • If the foam rubs against the E-Tube it will put extra strain on the servo.

  • Because the foam is not tied to the light board, the pieces will move around when inserting the electronics into the E-Tube.


#15

Very nice! I was trying to avoid contact with the E-tube. I figure the more I scratch it, the more stray light I’ll get. The camera is so sensitive to bubbles on the outside and dust on the inside of the tube.


#16

@robert_swarner this is very true. You can notice the little numbers on the foam that I used. I cut a bunch of different sizes to find one that just barely did not rub, but still blocked light.


#17

Iterate, iterate, iterate. :sunglasses: