Light does not emit in a centred way.

[tareko]

Describe the bug
The light points in an off-center way, which creates unexpected shadows that make it difficult or impossible to see structures properly. This can be mitigated through pulling the otoscope in and out to minimize drift off center.

To Reproduce
Steps to reproduce the behavior:

1. Place speculum on device
2. Insert into ear canal

Expected behavior
There should be very few shadows, and illumination should be clear.

Photos
If applicable, add photos to help explain your problem.

Failure Mode
The light shines off-center

Effect
Cannot clearly see structures of the ear canal and tympanic membrane.

Cause
The LED can be seated in several ways and can migrate. There is currently no great way to consistently seat the LED every time with precision.

Mitigation / Control

1. Stop distribution of device
2. Explore other ways of securing the LED
3. Consider whether another LED assembly is more appropriate

[tareko]

When I look at the Welch Allyn, I think what I'm seeing is that the light is emitted more or less evenly in a ring. I believe this happens through some kind of fiber optic ring that has likely a few LEDs shining on it. This means that the light gets to the speculum pretty much evenly without obstructing the view too much.

[doseofnoor]

The shadow you are describing may coincide with feedback received from 2 healthcare practitioners:

• "The otoscope head is rigid and so is the included/provided speculum which reflects light in retrograde fashion causing difficulty viewing the ear canal"
• "I am afraid if the reflection from the light to the inside of speculum will affect the ability to evaluate the condition."

[apopanda]

I ordered a bunch of fiber cable. I'll see if I can create a version of the otoscope with an LED in the base, and a fiber cable or two running along the bell housing and into the speculum.

[apopanda]

I edited the head to fit the LED board. I'm seeing shadows because of the LED being off-center. @tareko advise if this is in any way better. This is 14 degrees from vertical, aiming at around the middle of the speculum. The error can be corrected by moving the LED further back (which would mean we need to make the entire optical chain longer, which means that the lens probably isn't in focus anymore?), or by moving it higher up. I'll follow up with a fiber optic design too, once the package with it gets to me.

[tareko]

I edited the head to fit the LED board. I'm seeing shadows because of the LED being off-center. @tareko advise if this is in any way better. This is 14 degrees from vertical, aiming at around the middle of the speculum. The error can be corrected by moving the LED further back (which would mean we need to make the entire optical chain longer, which means that the lens probably isn't in focus anymore?), or by moving it higher up. I'll follow up with a fiber optic design too, once the package with it gets to me.

I can't quite tell, but is this an incomplete circle? If so, I think that's a non-starter. This particular problem is managed with a fiber optic ring in the Welsh Island models. However, the much older models have exactly this type of single light pointed out. I wonder if the angle is part of the problem. Obstructing the view is less problematic than having poor lighting.

[apopanda]

Incomplete circle. I can put a second LED on the top and see how that works. I'll see if I can find any photos of older otoscopes and reverse engineer; I saw that a lot of them use mirorrs / prisms with the light pointing upwards.

[apopanda]

Added a second LED, but the result isn't satisfactory. Need to go back to single LED and bring it up higher to flatten the illumination angle. When the speculum is really close to the wall, the spotlights merge together and it's a full circle, but I do remember you mentioning that it needs to shine out further out too.

[apopanda]

With the redesigned PCB head, this seems to be better. Full circle lighting, the LED is 5 degrees off center

[apopanda]

I've added a light trap along the bell of the otoscope. This significantly lowers the reflections from the housing