Optical system and methods including microlenses and light-blocking layer
An optical system is disclosed and includes an optical sensor configured to receive light and form an image. The optical system further includes a microlens film including a structured first major surface opposite a second major surface, the structured first major surface includes a regular array of spaced apart microlenses arranged across a width and a length of the microlens film and each microlens has an effective imaging area and configured to form an image onto the optical sensor. A light absorbing layer is disposed on the array of spaced apart microlenses and reduces the effective imaging area of each microlens by at least 10%. A display panel, the optical sensor, the microlens film and the display plane are substantially co-extensive with each other along the width and length of the microlens film.
1 . An optical system comprising:
an optical sensor configured to receive light and form an image;
a microlens film comprising:
a structured first major surface opposite a second major surface, the structured first major surface including a regular array of spaced apart microlenses arranged across a width and a length of the microlens film, each microlens having an effective imaging area and configured to form an image onto the optical sensor; and
a light absorbing layer disposed on and in contact with the array of spaced apart microlenses wherein the light absorbing layer is continuous on the structured first major surface and over the microlenses; and
a display panel, the optical sensor, and the microlens film being substantially co-extensive with each other along the width and length of the microlens film, such that when an object having a first spatial frequency of about 4 line pairs per mm is placed about 1.5 mm from the microlens film, each microlens is configured to form an image of the object on the optical sensor, the image having a modulation transfer function (MTF) of greater than about 0.2 at the first spatial frequency.
2 . The optical system of claim 1 , wherein when all but a first one of the microlenses are covered by the light absorbing layer so that only the first microlens forms an image of the object on the optical sensor, the modulation transfer function (MTF) of the image formed by the first microlens onto the optical sensor increases by less than about 10%.
3 . The optical system of claim 1 , wherein the microlens film includes polyethylene terephthalate.
4 . The optical system of claim 1 , wherein the object has a first angular frequency of about 6 cycles per radian, wherein when the object is placed in front of the microlens film, each microlens forming an image of the object on the optical sensor having a modulation transfer function (MTF) of greater than about 0.2 at the first angular frequency.