9 important parameters to consider when choosing an aspheric lens
The aspheric lens has a better radius of curvature and can maintain good aberration correction to achieve the desired performance. It is necessary to know some important parameters before choosing a suitable aspheric lens.
- Design Wavelength: The wavelength at which the lens works best. Lenses can also be used at other wavelengths. Contact DG optoelectronics to find out how the aspheric lens works at other wavelength.
- Numerical Aperture (NA) : a measure of the maximum angle of light acceptable to aspheric lens NA = sin (Φ)
- Clear Aperture(CA): By design, light can pass through the maximum diameter of the surface. Smaller than the actual spherical diameter, which is the physical aperture (PA) .
- Effective focal length (EFL) : the distance from the main surface to the focal point. The normal tolerance is 1% .
- Magnification: The ratio of image size to object size. The calibration lens is unrestricted.
- RMS WFE: the measurement of the chromatic aberration (error) in a lens. The diffraction limit means that, because of diffraction, the lens is guaranteed to conform to the theoretical limit (the maximum operating level that can be achieved in accordance with the laws of physics) .
- Outside diameter: The diameter of the outer cylinder of the aspheic lens, with a standard tolerance of 0.015 mm.
- Working Distance (WD) : also known as rear focal length (BFL), represents the distance from the back of the lens to the focal point.
- Center thickness(CT): Thickness in the axial direction of the lens.
In order to understand these parameters, it is necessary to know the disadvantages and advantages of aspheric lens, compared with spherical lens. In a word, aspheric lens has unique advantages over spherical lens, so it has been widely used in optical instrument, image and optoelectronics industry, such as digital camera, CD player, high-end microscope.