A displacement meter that measures displacement of an object includes a calculation circuit which calculates a displacement amount of the object using a cross-correlation function of plural images detected at different timings by a photoelectric conversion element array. The calculation circuit performs a Fourier transform on the images, applies a band-pass filter to the images having undergone the Fourier transform, and calculates the cross-correlation function using the images to which the band-pass filter has been applied. Assuming that a magnification of a light-receiving optical assembly is M, the number of pixels in the photoelectric conversion element array is N, and a pixel pitch is P (um), a low cut-off frequency HPF of the band-pass filter and a high cut-off frequency LPF of the band-pass filter satisfy: 3M/(N×P)≤HPF≤10M/(N×P), 40M/(N×P)≤LPF≤60M/(N×P).

A near-eye light field display device includes a plurality of sub-aperture light field emitting modules and a bi-telecentric lens group. The plurality of sub-aperture light field emitting modules are adapted to generate a plurality of sub-aperture light fields. The bi-telecentric lens group is disposed on one side of the plurality of sub-aperture light field emitting modules, wherein the plurality of sub-aperture light fields pass through the bi-telecentric lens group and are converted into an exit light field by the bi-telecentric lens group, and the exit light field is incident on a receiver.

A near-eye light field display device includes a plurality of sub-aperture light field emitting modules and a bi-telecentric lens group. The plurality of sub-aperture light field emitting modules are adapted to generate a plurality of sub-aperture light fields. The bi-telecentric lens group is disposed on one side of the plurality of sub-aperture light field emitting modules, wherein the plurality of sub-aperture light fields pass through the bi-telecentric lens group and are converted into an exit light field by the bi-telecentric lens group, and the exit light field is incident on a receiver.

To make an object to be observed observable with high resolution and to make an inclination angle of a surface of the object to be observed recognizable over a wide range.

An image observation system 100 provided with a lighting optical system 116 irradiating an object to be observed W with an illumination light and an observation optical system 122 collecting object light from the object to be observed W to guide to a detector 126, the image observation system 100 comprising an objective lens 122A opposed to the object to be observed W, a beam splitter 116B disposed on an opposite side to the object to be observed W with respect to the objective lens 122A, and a relay image RI of the illumination light splitting member 114 for dividing wavelength regions R, G and B of the illumination light into a plurality of different solid angle regions IS1, IS2 and IS3, being disposed in front of the objective lens 122A.

Various embodiments disclosed herein include techniques for maintaining multiple cameras in focus on same objects and/or at same distances. In some examples, a subordinate camera may be configured to focus based on the focus of a primary camera. For instance, a focus relationship between the primary camera and the subordinate camera may be determined. The focus relationship may characterize the trajectory of the lens position of the subordinate camera with respect to the lens position of the primary camera. In various examples, the focus relationship may be updated.

Various embodiments disclosed herein include techniques for maintaining multiple cameras in focus on same objects and/or at same distances. In some examples, a subordinate camera may be configured to focus based on the focus of a primary camera. For instance, a focus relationship between the primary camera and the subordinate camera may be determined. The focus relationship may characterize the trajectory of the lens position of the subordinate camera with respect to the lens position of the primary camera. In various examples, the focus relationship may be updated.

A zoom optical system according to an embodiment of the present invention includes a first lens group, a second lens group, a third lens group, and a fourth lens group which are sequentially disposed in a direction from an object side to an image side, wherein the second lens group and the third lens group are movable, a total track length (TTL) is less than 20 mm, and an effective focal length (EFL) in a telephoto is greater than 25 mm.

An adjustable teleconverter is provided that may be selectively adjusted between a base lens configuration and one or more tele-lens configurations without adding, removing, or replacing lenses from an optical system. In one example, a system includes a front lens group configured to form a first image at an intermediate image plane in response to radiation from a scene. The system also includes a teleconverter configured to project the first image to form a second image at a final image plane. The teleconverter comprises a relay lens group configured to be selectively positioned between the intermediate image plane and the final image plane to adjust a magnification of the second image. Additional methods, devices, and systems are also provided.

An adjustable teleconverter is provided that may be selectively adjusted between a base lens configuration and one or more tele-lens configurations without adding, removing, or replacing lenses from an optical system. In one example, a system includes a front lens group configured to form a first image at an intermediate image plane in response to radiation from a scene. The system also includes a teleconverter configured to project the first image to form a second image at a final image plane. The teleconverter comprises a relay lens group configured to be selectively positioned between the intermediate image plane and the final image plane to adjust a magnification of the second image. Additional methods, devices, and systems are also provided.

The invention relates to a hybrid objective with fixed focal length, which has a total of four lenses. Two lenses consist of glass and two lenses consist of plastic. The objective is suitable for use in a LID AR measurement system.