I had the same kind of experience making holograms in the physics lab. My transmission hologram was a blurry, faded mess. I suspected old chemicals, but to be honest we had no idea why. My lab partner and I tried about three times, with three total failures.
The reflection hologram turned out to be the best one the lab supervisor had seen in a decade. I have no idea why it worked at all, let alone why it turned out so good!
Both processes are simple conceptually, but incredibly finicky in practice. The interference fringes can be ruined by wind outside the lab shaking the walls, which then shakes the optical table through the floor. You can't feel it, but the hologram is ruined. The laser could have a short coherence length, and you wouldn't know it. If it warms up too fast, it'll shift the fringes. Don't cough. Don't bump the table. Don't bang the door. So on, and so forth.
The reflection hologram turned out to be the best one the lab supervisor had seen in a decade. I have no idea why it worked at all, let alone why it turned out so good!
Both processes are simple conceptually, but incredibly finicky in practice. The interference fringes can be ruined by wind outside the lab shaking the walls, which then shakes the optical table through the floor. You can't feel it, but the hologram is ruined. The laser could have a short coherence length, and you wouldn't know it. If it warms up too fast, it'll shift the fringes. Don't cough. Don't bump the table. Don't bang the door. So on, and so forth.