Low pass filter

Abstract

The invention discloses a low pass filter for a high-pixel image sensor. The low pass filter comprises a first quartz crystal piece, a quarter-wave plate and a second quartz crystal piece which are arranged in sequence along the light path direction. An infrared cut-off film is plated on the light incidence side surface of the first quartz crystal piece. A restrained wavelength shifting film is plated on the light outgoing side surface of the second quartz crystal piece. According to the low pass filter, the infrared cut-off film cuts off light in the infrared wave length zone, and the restrained wavelength shifting film has the advantages that ultraviolet cutting off is achieved, visible light high transmission is achieved, and wavelength shift caused by the incidence angle is small. The low pass filter is low in cost, light in weight and small in size, due to the fact that the restrained wavelength shifting film is an optics multilayer film system, performance is stable and reliable, and meanwhile a blue glass stable transmission-transition wavelength cut-off function, an ultraviolet cut-off function and an antireflection film function are achieved.

Description

technical field [0001] The invention relates to a low-pass filter for a high-pixel image sensor, which belongs to the field of optics and is mainly used in digital products such as high-pixel SLR cameras, mirrorless cameras, smart phones, and tablet computers. Background technique [0002] With the rapid development of digital imaging technology, the number of pixels of the image sensor CCD or CMOS is increasing, the pixel size is getting smaller and smaller, and the image resolution is getting higher and higher. At present, the pixel size of mainstream image sensors in the market is 3-10 microns, and the resolution reaches tens of millions of pixels. With the reduction of pixel size and the improvement of resolution, the requirements for low-pass filters used in high-pixel image sensors are becoming more and more stringent. [0003] The main function of the low-pass filter for high-pixel image sensors can be described as follows: The image sensor CCD or CMOS as a digital i...

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Problems solved by technology

However, there are two problems with this structure: first, the blue glass used has only been exclusively supplied by Japan so far, which is expensive, and because of its brittle mechanical properties, it is easily broken when cut into small pieces, and its chemical stability is poor, and it is easy to corrode in the air; Secondly, the total thickness of the low-pass filter is relatively thick, and the low-pass filter needs to be directly attached to the front of the sensor. A larger filter thickness will cause larger image aberrations, which must be avoided in high-pixel image sensors. of

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