There are many laser pointers in the market today, ranging in price from a few dollars to hundreds of dollars. In many instances, with the more expensive models you are paying for the fancy casing or adjustable optics. (There are only a handful of diode laser manufacturers in the world, so many times the expensive pointer and the cheap pointer actually contain the same laser.)...Fortunately, the simplest, most rugged (and often least expensive) laser pointers work best for the experiment described in this book.

The shoebox holograph set-up. Laser pen is mounted on the right. A conch shell on the left sits on a motion dampening foundation. A white card is used to focus where the film plate will be.