Film of aromatic polyethersulfone, process for the production thereof, and solution composition for the production thereof

An optically isotropic film of an aromatic polyethersulfone which is free of halogen containing solvent, which

• (A) comprises an aromatic polyethersulfone,
• (B) has a transmittance to visible light at a wavelength of 550 nm in the range of from 86 to 91%,
• (C) has a haze value in the range of from 0.1 to 1%,
• (D) shows a refractive index difference (.DELTA.n) of 0.0010 or less, which is a difference between a refractive index (n.sub.s) in the slow axis direction in an in-plane area of the film and a refractive index (n.sub.f) in the fast axis direction in the in-plane area,
• (E) has a refractive index ratio (n.sub.z /n.sub.f) of 0.9997 to 1.0000, which is a ratio (n.sub.z /n.sub.f) of a refractive index (n.sub.z) in a perpendicular direction with regard to a film surface to the refractive index (n.sub.f),
• (F) has a thickness in the range of from 30 to 300 .mu.m, and
• (G) has a thickness nonuniformity in the range of from 0.1 to 1% based on an average film thickness.