A catadioptric optical system operates in a wide spectral range. Sealant compositions comprising the multifunctional sulfur-containing polymers are also disclosed. In another embodiment, rather than grid lines being introduced into the molds used to form retro-reflective sheets, the grid lines are formed directly on or in the retro-reflective material itself during or after creation. In one example, the first type of signal is a MoCA signal and the second type of signal is a cable signal. The source and drain junction regions 17 and 18 have a thickness greater than that of the channel region 19, and the thickness of the LDD region 15a continuously varies so that the thickness gradually increases from the channel region 19 side toward the source junction region 17 side and the drain junction region 18 side. The nailed portions are formed by plastically deforming the cage at a substantially middle portion of the longitudinal length of the needle roller.