1.ZnSe (Zinc Selenide) CO2 Laser Focusing Lenses (Plano-convex Lenses). 2.Meniscus lenses form the largest and most popular part of our product range. 3.ZnSe CO2 Negative Laser Focusing Lenses (Plano-Concave Lenses). 4.CO2 Laser Focusing Lenses Used in Typical Industrial Lasers.