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UltravioletPhotography

Integrating sphere built on a shoestring


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Last year when i got my DH-2000-BAL, I thought it was a strong powerful light-source and wanted to check if it was powerful enough for measurements with an integrating sphere.

For testing the principle I put one together in best MacGyver style, with simple parts.

 

The sphere was formed around a toy rubber ball, diameter 61.5mm.

With thin plastic cling-foil around the ball the sphere-cavity was moulded in two steps with Plaster of Paris.

This way I got two half domes that fit well together.

I built the case by combining several (12) step rings of different dimension and a metal light shade.

Suitably chosen rings give the unit M42 threads in both ends.

My measurement setup is based on M42 extension rings for holding diverse optical components.

The input port was drilled to 24mm diameter and the measurement connector, holding the fiber is an RF SMA-connector where I removed the center conductor and PTFE insulation tube.

 

It was substantially more work to shape one of the sides to make the block of plaster match the shape of the step rings.

The opposite side was moulded directly into the shade and step-ring structure.

 

post-150-0-78000800-1564763468.jpg

 

post-150-0-39852900-1564764592.jpg

Unfortunately the DH-2000-BAL, was not strong enough for meaningful measurements with an integrating sphere and the sphere was put aside. :angry: :angry: :angry:

 

Yesterday I finally got an idea to test if the Convoy S2+ could work in this setup:

post-150-0-88164600-1564764653.jpg

:) :) :)

To be continued in another measurement topic.

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Outstanding!

 

I'll be interested in seeing the spectral response of plaster of paris.

I have a mongrel sphere I got on eBay.

I don't have enough constructed yet to be able to test its response.

 

Clearly you are using Arca rails for your optical bench.

Where did you get the great articulating posts that you are using to mount your components?

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Outstanding!

 

I'll be interested in seeing the spectral response of plaster of paris.

I have a mongrel sphere I got on eBay.

I don't have enough constructed yet to be able to test its response.

 

Clearly you are using Arca rails for your optical bench.

Where did you get the great articulating posts that you are using to mount your components?

 

I do not think the spectral response is extremely important as long as it not problematically low.

I think it is good enough.

Just as when doing filter transmission measurements the combined characteristics of light source and optical components is eliminated during the reference calibration.

 

Plaster of paris was one of the components in the DIY UV-reflectance references discussed on the forum a year or so ago.

I think Jonathan (JMC) was the initiator for one of the topics about that.

 

The components for the optical setup are like these:

https://www.ebay.com...7hoEhOuV91JZeLg

https://www.ebay.com...KAAAOSwuMFUgBhW

https://www.ebay.com...SS/253589152682

plus some screws, washers and nuts.

 

The laser holder clamp-tube can be unscrewed from it's steel-stud and replaced with other mechanical parts like the extension tube.

The thread is a M5 and by just drilling and cutting a fitting thread in the thickest part of the extension tube's wall the tube can be refitted onto the stud's short thread.

The biggest version of clamp-diameter for lasers is 23.5mm and the Convoy is thicker. I had to cut the tube open and by bending forcing the diameter wide enough.

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For your measurement port, the naked end of the fiber cable just sticks into the sphere, correct? You don't have any optics or anything between the fiber and the interior of the sphere?
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For your measurement port, the naked end of the fiber cable just sticks into the sphere, correct? You don't have any optics or anything between the fiber and the interior of the sphere?

Correct.

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