Non-Destructive Micro Visual Inspection

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Microscopic non-destructive testing is a new service offered by Dowrick's Scientific Services.

Our very high powered microscopes and image analysis techniques allow us to inspect organic as well as inorganic materials for all aspects - surface texture, pore size, manufacturing tolerances, etc. 

This service is well suited to the needs of any QC department that needs to backup its own in-house observations with calibrated external data.

Data can be provided in the form of a written report, or captured as stills, or video.  

QC managers can use our live feed option to ensure that the data that is captured is accurate and of the desired area.

Case Study

A B S T R A C T

Required was the optical inspection of 10 fibre optic glands, 5 each from 2 separate suppliers.  Data to be supplied as medium resolution calibrated photos, with indication of aperture size.

Measure the diameter of the hole in 10 fibre optic glands

The AKAS certification for the slide used in this case study can be downloaded here.

METHODOLOGY

Microscopic equipment was set up using sample one to establish the best optical conditions.  After that, no changes were made to the microscope illumination or magnification. 

The first image captured was a calibrated stage micrometer (CS5225).

Sample 1 through 10 when then imaged  sequentially.

Image  manipulation software was first calibrated using the image of CS5225

The stage micrometer image was superimposed onto each of the gland images.

4 manual measurements were taken of each gland, each differing by 45 degrees.

The final image to be captures was CS5225.  The data was compared to the first capture to ensure that no changes had taken place due to thermal expansion / contraction of equipment during the test procedure.

RESULTS

Images 1 to 5 were from vendor 1 

Images 6 – 10 were from vendor 2

 

The samples from V1 seemed to consistently have internal contamination of various sizes. 

 

This was first observed in sample 1, with the detritus blocking 20% of the hole.  Unfortunately this material moved between initial examination and photography, and cannot be seen in the photo.  After a brief discussion with **** it would appear likely that the contaminants might be due to inhouse testing at ****.  The internal wall can be seen to have a black scuff mark consistent with the theory that a carbon coated cable has been inserted at some point.

 

Sample 4 seems to be completely blocked.  Again, after discussion with **** I re-examined this sample and found the blockage almost impossible to image at any depth.  This is consistent with the contaminant being a high quality optical glass fibre that has broken off internally, probably during in-house testing.

 

The measured diameters were as follows

 

1: 436 micrometers

2: 435 micrometers

3: 437 micrometers

4: 435 micrometers

5: 438 micrometers

 

6: 441 micrometers

7: 443 micrometers

8: 442 micrometers

9: 440 micrometers

10: 446 micrometers

 

The mean diameters were

 

V1 436 micrometers

V2 442 micrometers

 

The scale was a 1mm UKAS calibrated slide (CS5225) photographed immediately prior to capture of the first image, and after the capture of the final image.  The certificate has been attached, and you are welcome to print it out for your records.

ADDITIONAL COMMENTS

The level of internal contamination is probably not due to the original manufacturer as capped samples were consistently cleaner.

Samples from V1 showed obvious milling features on the external apical surface.   In a blind trail it would have been easy to differentiate between the 2 suppliers.

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