No one manufacturer makes Retina displays and different suppliers currently make Retina Displays for various Apple Products. For example, Samsung have supplied iPad displays, while LG makes MacBook Pro, iPhone and iPod Touch displays.
Steve Jobs, when launching the iPhone 4, said that a Retina Display needed 300 PPI for a device held 10 to 12 inches from the eye. Pixels-per-degree (PPD) is used as a way to express this as a unit, which takes into account both screen resolution and how far away the device is being viewed from. Taking Jobs’s predicted 300PPI, the threshold for a Retina Display starts at 57 PPD.
