OP.DI.MA. is an optical grade white plastic material with an excellent diffuse reflectance characteristic and is highly durable. The diffuse reflection characteristic is close to that of a perfect lambertian reflector ensuring the best uniform light distribution inside the sphere. Its spectral reflectance covers a wide spectral range from the ultraviolet to the near infrared (250 nm to 2500 nm) with > 95 % reflectance and a peak reflectance of > 98 % in the visible to NIR region.