By arranging multiple line heating types and lengthten the focal length from the rated distance, the condensing width can extend and a wide range of heating can be performed. (Out focus)

Of course, even with the plane heating type, a wide range of heating is possible by arranging multiple units in the same way.
The plane heating type is effective when you do not want to heat anything other than the object to be heated because the focal width of the heater does not change even if the distance is engthened
If you want to heat in a wider range than the width of the condensing mirror, select the linear heating type.

There are two points to note.

Even if the focal length is the same, the shorter the focal length, the higher the output density, and the higher the temperature of the lamp.

Since both ends of the condensing mirror is the rising part, the part for stable heating is the length excluding on both ends.

There is also a method to prepare a heater for the both ends separately.