"Transmitted light gadget" is not a standard term in any scientific or technological field. It's possible the phrase is being used in a specific context, or it might be a misnomer.

To understand what you're referring to, I need more information. Could you please provide some context or additional details? For example:

* Where did you encounter this term? (e.g., a website, a book, a conversation)

* What is the intended purpose of this gadget? (e.g., viewing something, taking a picture, measuring something)

* Are there any other keywords or clues associated with the term? (e.g., microscope, camera, light source)

With more information, I can help you understand what the term might refer to.