HTC Patent | Optical lens, optical system and method of manufacturing optical lens

Patent: Optical lens, optical system and method of manufacturing optical lens

Publication Number: 20190025472

Publication Date: 2019-01-24

Applicants: HTC

Abstract

An optical lens adapted to be disposed on a transmission path of a light beam is provided. The optical lens includes a plurality of lenticular lens units extending along the same direction, and the lenticular lens units are disposed side by side along a direction perpendicular to the extension direction thereof, wherein each of the lenticular lens units has a height relative to a bottom surface of the optical lens, adjacent two of the lenticular lens units have a height difference D therebetween, and the optical lens satisfies D .gtoreq. 2 ln ( 2 ) .pi. n .lamda. 2 .DELTA..lamda. , ##EQU00001## wherein n represents a refractive index of the optical lens, .lamda. represents a central wavelength of the light beam, and .DELTA..lamda. represents a spectral bandwidth of the light beam. In addition, an optical system and a method of manufacturing an optical lens are also mentioned.

Background

Linear light obtained by projecting laser light through a lenticular lens may be used as an emission source for optical tracking. For example, this emission source may be applied in a positioning and tracking system in virtual reality (VR). More specifically, laser light emitted by a laser light source in a base station or a lighthouse passes through a lenticular lens to form linear light, and a motor in the base station or the lighthouse having the lenticular lens mounted thereon continuously rotates to thus enable the linear light to continuously scan a specific space. A plurality of light sensors are disposed on a head mounted display (HMD) or a controller to detect the linear light emitted from the base station or the lighthouse. According to rotation angle and frequency of the motor as well as a time difference between time points at which the linear light is detected by each of the light sensors, the system can determine six-axis coordinates of the HMD or the controller in the space.

However, in light pattern distribution of such linear light, a problem of non-uniform brightness often arises in, for example, bright regions and dark regions of the linear light. More specifically, when the dark regions of the linear light scan over the light sensors, the dark regions of the linear light may not be detected by the light sensors, and positioning accuracy is thus affected.

Summary

The disclosure provides an optical lens causing light projected therethrough to be uniform in brightness.

The disclosure provides an optical system projecting light which is uniform in brightness.

The disclosure provides a method of manufacturing the aforesaid optical lens.

An embodiment of the disclosure provides an optical lens adapted to be disposed on a transmission path of a light beam. The optical lens includes a plurality of lenticular lens units extending along the same direction, and the lenticular lens units are disposed side by side along a direction perpendicular to the extension direction thereof, wherein each of the lenticular lens units has a height relative to a bottom surface of the optical lens, adjacent two of the lenticular lens units have a height difference D therebetween, and the optical lens satisfies

D .gtoreq. 2 ln ( 2 ) .pi. n .lamda. 2 .DELTA..lamda. , ##EQU00002##

wherein n represents a refractive index of the optical lens, .lamda. represents a central wavelength of the light beam, and .DELTA..lamda. represents a spectral bandwidth of the light beam.

An embodiment of the disclosure provides an optical system including a light source and an optical lens. The light source is adapted to emit a light beam. The optical lens is disposed on a transmission path of the light beam. The optical lens includes a plurality of lenticular lens units extending along the same direction, and the lenticular lens units are disposed side by side along a direction perpendicular to the extension direction thereof, wherein each of the lenticular lens units has a height relative to a bottom surface of the optical lens, adjacent two of the lenticular lens units have a height difference D therebetween, and the optical lens satisfies

D .gtoreq. 2 ln ( 2 ) .pi. n .lamda. 2 .DELTA..lamda. , ##EQU00003##

wherein n represents a refractive index of the optical lens, .lamda. represents a central wavelength of the light beam, and .DELTA..lamda. represents a spectral bandwidth of the light beam.

An embodiment of the disclosure provides a method of manufacturing the aforesaid optical lens, the method including the following steps. A mold having a cavity having a shape corresponding to the lens units is provided. A lens material is filled into the cavity. The lens material is cured. The cured lens material is separated from the mold.

Based on the above, an embodiment of the disclosure proposes an optical lens including a plurality of lenticular lens units, and adjacent two of the lenticular lens units have the height difference D therebetween. The optical lens satisfies

D .gtoreq. 2 ln ( 2 ) .pi. n .lamda. 2 .DELTA..lamda. , ##EQU00004##

wherein n represents the refractive index of the optical lens, .lamda. represents the central wavelength of the light beam, and .DELTA..lamda. represents the spectral bandwidth of the light beam. With the above design, it can be prevented that, after the light beam passes through two adjacent lenticular lens units with no height difference therebetween, interference occurs and affects uniformity of the light. In addition, since adjacent two of the lenticular lens units have a height difference therebetween, in the light obtained by projecting the light beam through the optical lens, formation of dark regions with relatively low brightness can be prevented, so that the light obtained by projecting the light beam through the optical lens is more uniform in brightness.