Glass Cutting Bessel objective with Variable Depth of Focus

Our Variable DOF  Bessel objective is  a Diffractive based optical module that to focuses a single mode Gaussian input beam into a  tight spot with  2 um waist size and a variable depth of focus (DOF) ranging from 0.08-1.5 mm in air. The Variable DOF Bessel objective has a constant spot size over the entire adjustment range , optimal for systems that cut different thickness of glass and need to maintain the same cut quality. 

The Variable DOF Bessel Objective is normally used in the near IR wavelength range (1030-1080nm) for laser glass cutting applications,  and can be used to cut both thin and thick glass. We also offer a variant at green wavelengths (515-532nm) and can offer custom option for other wavelengths, as required . 

Each Bessel Variable DOF e module is shipped out of our factory an individual testing report showing focusing performance at maximum and minimum DOF. 

Variable DOF  Bessel Objective  unique characteristics:

  •  Flexible cutting – Adjustable DOF from ~80 um to 1500 um in Air (X1.5 in glass) 
  • Constant spot size of 2um over the entire  range of DOF values
  • Complete solution (Bessel generator and  focus objective  in one element)
  • High LDT, Ultra Short Pulse compatible- all parts are  fused Silica optics    
  • Diffractive Axicon generates  perfect wavefront, no Bessel distortions and no dead area in Axicon apex 

Bessel objective normalized intensity in  focus for different adjustment positions  from minimal DOF ( blue) to maximal (yellow) 

VB module DOF profiles

Specifications of standard Variable DOF Bessel Objective :

* Depth of focus (DOF)  in the processed material is equal to  DOF in air multiplied by the refractive index of the material. 

** All modules come with  screw-on protective window that can be easily removed and cleaned as needed. for laser applications that do not generate debris , removing the protective window will  increase  work distance . Working range increases  with DOF, from 8.7mm for minimal DOF to 11.6mm  for maximal DOF.

PN
Wavelength Range
Input Beam Diameter (exp^-2)
DOF range in Air*
Waist Diameter (exp^-2)
Working Distance range with/ without protective window**
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VB Module-001-I2J
1030-1064nm
3mm - 8mm
0.08mm-1.5mm
2um
7.2 - 10.1mm /8.7 - 11.6mm
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Have any questions you can’t find the answer for, or you need different parameters for your Variable DOF Bessel Objective? Contact us