Industrial News

　　How to evaluate the quality of a lens?MTF is the standard for comprehensively evaluating the imaging quality of a lens.The MTF two-dimensional coordinate curve usually has a value(0~1)on the Y axis and a spatial frequency(lp/mm)on the X axis,that is,how many"line pairs".The low frequency evaluates the contrast(contrast)of the image after imaging,and the high frequency is to examine the clarity and resolution of the lens,that is,the ability to distinguish details.For example,photographic lenses usually use 10lp/mm to examine the contrast effect.Generally,the MTF value should be higher than 0.7,and the high-frequency inspection is 30lp/mm.Usually,the half field of view is greater than 0.5,and the peripheral field of view is greater than 0.3.(Aoyi Technology)

　　However,for some optical instruments or industrial lenses,there are higher requirements for high frequency,so how to calculate the high frequency we need to investigate?it's actually really easy:

　　Frequency=1000/(2×sensor pixel size)If the sensor pixel size you use is 5um,then the MTF high frequency should be 100lp/mm,and the measured value of MTF is higher than 0.3,then it is a relatively good lens.

　　MTF cannot reflect the aberration of distortion,so distortion is proposed separately.Distortion,that is,deformation,is divided into pincushion distortion and barrel distortion.

　　Distortion is related to the field of view,the larger the field of view,the greater the distortion.For conventional photographic lenses and surveillance lenses,the distortion is acceptable within 3%.For wide-angle lenses,the distortion can be 10%~20%,while for fisheye lenses,the distortion can be 50%~100%.

　　So if you are sure how much distortion should be controlled for the lens you want?

　　First of all,clarify the purpose of your lens.For example,the above is photography or monitoring,so the distortion is allowed within 3%.If your lens is used for measurement,the distortion should be less than 1%,or even lower,depending on your measurement system.allowable systematic error.