Focal length, also known as focal length, is a measure of the concentration or divergence of light in an optical system. It refers to the distance from the center of the lens to the focal point of the light.As shown in the figure below:

   In laser marking equipment, after the laser is reshaped, the laser will illuminate the focusing field lens with a parallel beam. Most conventional laser marking equipment USES a convex lens. After optical refraction, the convex lens focuses the parallel light beam to a focal point, forming a focal plane.The vertical distance from the optical center of a convex lens to the focal plane is what we call the focal length.We usually use F equals what the focal length is.Most laser equipment with a focus field mirror will be labeled.For example: F = 163;F = 254 and so on.Focusing field lens is a very important optical accessory in laser marking equipment.
 

  The laser generates the laser and incident it to the vibrator deflector lens, and forms our preset marking pattern path with the control software. The vibrator lens refracting the laser to the focusing lens, and focusing energy to the focal length surface to complete the laser engraving.From this picture, we can see very vividly that the laser beam after being focused is just like a tapered needle. Therefore, to make the laser energy sharper, we have to shake the laser marking machine z-axis to rise and fall and adjust it to the focal length surface.

Conventional method of finding focal length:

The first: continuous light - out test method.

  In marking paint a software about a centimeter square or round, conventional after filling, the laser laser energy is transferred to set parameters column is bigger, use frequency, and then check the continuous marking, put a piece of metal in the product surface laser projection position card obstructions, such as continuous light marking, shake the Z axis movements, until the function to the strongest metal business card energy laser, the most clear voice, the brightest colors, is basically the focal length, lead the test a few times more, find the right focal length.This method is suitable for 1064 - nm wavelength of the optical fiber laser marking machine, semiconductor laser marking machine, end face pump laser marking machine, 355 nm laser marking machine, uv 532 nm green laser marking machine, etc., co2 laser marking machine can look for a piece of blank paper, and then draw a box in the marking software, continuous light shake the Z axis, hit the paper on the line for the focal plane when the finest.

The second method: measuring focal length.

  After the device manufacturer informs the current device of the focal length data, it can be recorded and then every time the product is switched.One end of the steel ruler can be placed directly on the surface of the product.The scale value refers to a certain reference surface on the field mirror and can be shaken up and down to the scale data.This method is suitable for all laser marking machines, but has the disadvantage that it is not very practical if the product required for the radium carving is in a concave position or does not fit properly into a steel rule.
 

The third kind: double red light to point value method.

  This method requires the equipment to be equipped with this hardware configuration when it leaves the factory. One or two oblique red lights should be added to the galvanometer or beside the galvanometer. Some principles of a right triangle are used to find another right Angle side on the plane where the focal length is located by using a fixed right Angle side and two overlapping hypotenuses.You can quickly find the focal length by shaking it up and down until the two red indicators coincide.Although this method is convenient and fast, it requires the equipment manufacturer to cooperate with the secondary device. In addition, if the device is not properly adjusted or shifted in the middle, it is easy to cause misdirection and form the wrong focal length surface.