That's exactly the problem

Immigration officers do not have the knowledge of your specific area,so their understanding of "same field" is no better than Rabbit's (or any people not in that filed, even that person have higher education or graduate education)understanding. Although you know they are similar (which I don't think so, because I am also not in that area and frankly don't understand why eye glasses have anything to do with semiconductors), the immigration officers most probably will not agree on this and will give you a hard time.