28 Sep 2006 In the packing industry, lasers are often used to perforate materials. It is not only important to maintain high throughput levels, but to make small, precise holes with even spacing. Diffractive elements are particularly well suited to the production of these holes in thin substrates. The diffractive element duplicates the incoming beam, which is collimated with a 0° angle of incidence, into a number of beams (which are also collimated) corresponding to the type of element with an exactly defined angular separation. The spacing between the generated spot beams is defined by the focus length of a subsequent lens. Optically speaking, the incoming beam and outgoing beams with respect to the spot diameter and beam profile can be treated as identical. In duplication one-dimensional (point line) and two-dimensional (point matrix) arrays are available.
Generating multiple, identical beams with an equal distribution of intensity and constant spacing allows for a larger throughput. Usually, in this way using an x-y table can be avoided.
Features of Multi-spot Elements:
- Precise spacing between the holes through precise angle separation.
- Constant spacing between the spots without the need for adjustment, even with vibrations in the system, as the holes are imaged with one element.
- Homogeneous distribution of intensity: The difference between the spots with the 1 x 2 and 2 x 2 elements is +/-1%, whereas with the other elements it is somewhat higher.
- The spacing between the spots is insensitive to x, y, and z displacement in the system.
- High damage threshold: With HoloOr’s manufacturing process high damage thresholds like those of standard quartz glass or ZnSe substrates can be achieved.
- Antireflex coating for the reduction of back reflections are available on an optional basis for all substrates.
Up to 20 percent of the energy is distributed to higher orders. Upon request, HoloOr will let you know where these orders are located. They lie at a maximum of 5-10% of the spot intensities. If this is not desired, a mechanical masking should be considered with the design.
Through the energy of the higher orders the system can become very hot. Therefore, a good ventilation system is important for high power lasers.
Although insensitive to x, y, and z displacement, an adjustment has to be made in rotation along the optical axis.
|
