A "Dichroic" filter is better described as a "heat glass", ... an Infrared filter for *really invisible* infrared radiation, otherwise known as "heat".

Its function is to absorb heat in the optical path and keep the negative stage relatively cool to prevent "popping" out of focus, or in extreme cases (and not ALL that extreme either), damage to the film.

You CAN get away without it. Personally - I wouldn't try.