A converter lens has negative refractive power, and is disposed on an image side of a master lens so that a focal length of an entire system becomes greater than a focal length of the master lens alone. The converter lens includes a first lens element closest to an object and a second lens element next to an image side of the first lens element with a space between the first lens element and the second lens element. A focal length of the converter lens, a focal length of an air lens formed by the first lens element and the second lens element, the shape of an image-side lens surface of the first lens element, and the shape of an object-side lens surface of the second lens element are determined as appropriate.

A machine learning based imaging system comprises an imaging apparatus for attachment to an imaging sensor of a mobile computing apparatus such as camera of a smartphone. A machine learning (or AI) based analysis system is trained on images captured with the imaging apparatus attached, and once trained may be deployed with or without the imaging apparatus. The imaging apparatus comprise an optical assembly that may magnify the image, an attachment arrangement and a chamber or a wall structure that forms a chamber when placed against an object. The inner surface of the chamber is reflective apart and has a curved profile to create uniform lighting conditions on the one or more objects being imaged and uniform background lighting to reduce the dynamic range of the captured images.

A removable camera lens attachment has at least two optical elements, wherein the at least two optical elements are aligned to share an optical axis with a prime lens of the camera. The lens attachment has at least two curved surfaces. The at least two optical elements have a first surface that is conditioned to reflect a first portion of the incident light away from the image plane as reflected stray light and a second surface that is conditioned to reflect a second portion of the reflected stray light back toward the image plane to form a ghost image on an image plane of the prime lens. The lens attachment alters the effective focal length of the prime lens by no more than 15%.

A removable camera lens attachment has at least two optical elements, wherein the at least two optical elements are aligned to share an optical axis with a prime lens of the camera. The lens attachment has at least two curved surfaces. The at least two optical elements have a first surface that is conditioned to reflect a first portion of the incident light away from the image plane as reflected stray light and a second surface that is conditioned to reflect a second portion of the reflected stray light back toward the image plane to form a ghost image on an image plane of the prime lens. The lens attachment alters the effective focal length of the prime lens by no more than 15%.

A magnifying device (100) with multiple magnifications including: an outer shell (10) forming a body of revolution with an axis of revolution (X-X) and having an inner cavity (5), a first lens (30) mounted at a first end (13) of said outer shell (10), and a second lens (20) capable of moving between a retracted position and an extended position in which said second lens (20) is superimposed on said first lens (30) so as to change the optical characteristics of the magnifying device (100).

A magnifying device (100) with multiple magnifications including: an outer shell (10) forming a body of revolution with an axis of revolution (X-X) and having an inner cavity (5), a first lens (30) mounted at a first end (13) of said outer shell (10), and a second lens (20) capable of moving between a retracted position and an extended position in which said second lens (20) is superimposed on said first lens (30) so as to change the optical characteristics of the magnifying device (100).

An attachment optical system attachable to and detachable from an imaging optical system includes a first converter optical system attachable to an object side of the imaging optical system, and a second converter optical system attachable to an image side of the imaging optical system. The first converter optical system includes a first unit consisting of a dome-shaped cover. A predetermined condition is satisfied.

A lens attachment, used with an objective lens, including from object side to image side, a first lens element with positive power, a second lens element with negative power, a third lens element with positive power, a fourth lens element with negative power, and a fifth lens element with positive power; the second and third lens elements form a doublet by adhesive; at least two of the third, fourth and fifth lens elements are anomalous dispersion lenses.

A method of additive manufacture is disclosed. The method may include creating, by a 3D printer contained within an enclosure, a part having a weight greater than or equal to 2,000 kilograms. A gas management system may maintain gaseous oxygen within the enclosure atmospheric level. In some embodiments, a wheeled vehicle may transport the part from inside the enclosure, through an airlock, as the airlock operates to buffer between a gaseous environment within the enclosure and a gaseous environment outside the enclosure, and to a location exterior to both the enclosure and the airlock.

A method of additive manufacture is disclosed. The method may include creating, by a 3D printer contained within an enclosure, a part having a weight greater than or equal to 2,000 kilograms. A gas management system may maintain gaseous oxygen within the enclosure atmospheric level. In some embodiments, a wheeled vehicle may transport the part from inside the enclosure, through an airlock, as the airlock operates to buffer between a gaseous environment within the enclosure and a gaseous environment outside the enclosure, and to a location exterior to both the enclosure and the airlock.