Bad channels in the prototype waveguide

Hideyuki SakamotoTracker meeting,

10th May,2006

Contents• Waveguides to be checked

• Method for checking• Results and comment• Next to do

Waveguides to be checked

• 3 kinds of waveguide– New-type Internal

Waveguide #?(no label)– Modified Waveguide #104– Old-type Waveguide #9

Internal waveguideInternal waveguide

Modified waveguideModified waveguideOld-type waveguideOld-type waveguide

D0 connector (128channels)Old-type MICE connector

Internal connector

New-type MICE connector

Method for finding bad channels• 2 kinds of method are applied.

Method (1): Taking pictures by a digital camera with flash from the surface of D0 connector ( or Inner connector). Some bad channels seems shining, which are considered as a reflecting light from bad surface inside the fiber.

Method (2): Looking fibers by eye with injecting light from the connector and finding bad fibers where light is leaking.

• And confirming that bad channels found at (1) and (2) are same or not.

(1) Reflecting light (2) Leaking light

Internal Waveguide

#1

#3

#2

Reflecting light checkReflecting light check Leaking light checkLeaking light check

Bad channel found at reflecting light check are consistent with those found at this check.

Modified-type#104

#1#2#3

#4#5

#7#8

#9

#6 Bad channel?

Reflecting light checkReflecting light check Leaking light checkLeaking light check

8 channels within found at reflecting light check is consistent.

Another 2 channels found are not found at this check.

And also another 5 fibers are newly found at this check.

Flash light from camera

Old-type Waveguide#9

#1 #2 #3

#8#9

#10#7#6

#5#4

Reflecting light checkReflecting light check Leaking light checkLeaking light check

2 channels found at reflecting light check is consistent. But 8 channels were not found at this check.

And another 20 fibers are newly found as crack…

Results and Comment• It is found that bad channels are caused by crack, which are

specified by both finding reflecting light and leaking light from the fiber. But, some channels are not consistent with both check. I think that– Small crack <= reflecting light is maybe too small to find. – Crack just around connector <= this cannot measured by this test.

• Possible reason for the damage– At the time when cutting from spool

• This maybe makes cracks around connector. This is not so problem due to using hot knife.

– At the time when polishing or mounting into connectors• Before attachment with connector, the main reason to make cracks

is bending fibers to small radius. And after attachment, connectors are needed to fix with waveguide not to make tension with fibers. Checking the manufacturing process again if there is the cases to damage fibers.

– At the time when carrying out waveguides• This could be resolved by packing in the case not to stress the

fibers.

Next to do • Transmission test

– This is required for quality control of waveguide, and confirming its validity using waveguide including bad channels.

– Injecting light from the connector though a filter ( making uniform light and adjusting light yield) and measuring light yield at the another connector by digital camera or CCD camera.

– Estimating (relative) transmissions at each channels by calculating luminosity from each pixels.

Rolled / straight Digital camera/ CCD

ND filter

Light source

Temporary Setup