Where can I find cuvettes with transparent caps?

[KShah423]

I am a high school student replicating the Faraday Effect. I'm using cuvettes to fill with liquids and air to test the polarization of light. I found cuvettes such as these:

The problem is the cap. The cuvettes are to be inserted inside of a solenoid, so the only possible way for them to be properly situated is horizontally. However, light from a laser cannot pass through the cap. Is there an affordable solution to finding UV plastic cuvettes that can be placed horizontally? Thank You.

 

[Tom.G]

How about an alternate approach?

Support the solenoid vertically, even put it on two stacks of books if nothing else is available.
Put a microscope slide under the solenoid so you have a support for the cuvettes and place the cuvette in the solenoid. Then you can leave the cap off.
The light source can be either under the solenoid pointing upward, or aimed at a mirror or prism under the solenoid to aim the light upward.
The sensor could rest on top of the solenoid or you could place another mirror up there to redirect the output light to the sensor.

Or if it is easier, put the light source above the solenoid and the sensor below it.