Collimating lens and projection module

Abstract

The invention provides a collimating lens and a projection module. A laser emitter side is set as an object side and a measured object end is set as an image side. A first lens having the positive focal power, a second lens having the negative focal power, a third lens having the positive focal power, and a diaphragm are arranged successively along the optical axis from the object side to the image side. The object side surface of the first lens is a convex surface; the object side surface of the second lens is a concave surface; the object side surface of the third lens is a convex surface ora near plane and the image side surface is a convex surface. The diaphragm is arranged between the third lens and a measured object. The first lens, the second lens and the third lens are all made ofplastic materials. The collimating lens meets the following conditional expression: (dn / dt) 1 is less than -30*10<-6> / DEG C, (dn / dt) 2 is less than -30*10<-6> / DEG C, and (dn / dt)3 is less than -30*10<-6> / DEG C. According to the invention, the changing rates of refractive indexes of the three lenses with the temperature are defined clearly and thus reasonable matching of the thermal expansion characteristics of the lenses is realized, so that the stable focal length is realized. The collimating lens and the projection module are suitable for different temperature applications.

Description

technical field [0001] The invention relates to the field of camera lens technology, in particular to a collimator lens and a projection module. Background technique [0002] With the rapid development of smart phones, innovative technologies are constantly emerging in the camera functions of mobile phones, such as the 3D imaging technology promoted by Apple, which is an optical sensing technology based on 3D structured light, which can be used for face and gesture recognition, enhanced The camera function brings new AR applications, transforming optical images from the past two-dimensional space to three-dimensional space, thus bringing a more real and clear perception experience. [0003] 3D structured light means that after specific laser information is projected onto the surface of an object, it is collected by a camera, and information such as the position and depth of the object is calculated according to the change of light information caused by the object, and then t...

AI Technical Summary

Problems solved by technology

[0004] However, in the existing smartphones, as the temperature of the use environment changes, the focal length f of the lens changes greatly, resulting in a significant change in the angle of the lens projected light, which will change the original light information, resulting in the entire There are errors in the calculation of the system, which affect the accuracy of the contour restoration of the three-dimensional object. There is also the case that the projected image point becomes larger with the change of temperature, which will also lead to a decrease in the definition of the three-dimensional object restored by the system. Therefore, with the use of When the ambient temperature changes, it is particularly important that the field of view angle and the size of the spot of the light information projected to the measured object do not change greatly

[0005] In addition, the first lens of the traditional collimator lens close to the laser transmitter is a molded glass lens. This molded glass lens is too small, difficult to produce and process, low yield, and difficult to mass-produce, which greatly increases the production cost.

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