| Mark | Laser | Power Demand | M² | Scan Speed | Hatch Spacing | Energy |
| Black | redENERGY G4 20W RM-Z | 50% | <1.6 | 1800mm/s | 3µm | WF1@500kHz – one pass |
| White | redENERGY G4 20W RM-Z (2WF) | 90% | <1.6 | 3000mm/s | 3µm | WF0@180kHz – two passes |
A Quick Response Code (QR code) is a type of matrix barcode, first designed for the automotive industry in Japan. The QR code system was initially invented to track vehicles during manufacture. Today, QR codes are used in a much broader context for commercial and convenience purposes aimed at mobile-phone users.
The challenge is to mark the QR codes in a short amount of time and to be readable using a smartphone or barcode reader. A series of 10mm marks were created in this application: a black, white and combined mark.
In this application, the black mark is created by surface oxidation. The challenge is to heat the surface without any signs of melting. Within the mark area, the heating should be uniform to gain a good quality mark and this can be achieved by controlling the laser and scanner parameters. The black oxidated mark was produced in a single pass, created in 23.3 seconds.
The difficulty in producing a white mark is to achieve an even finish, viewable from different angles. The best results are achieved by using high scan speeds combined with low pulse energy, which gives a uniform mark. The white mark was produced in two passes, achieved in 4 seconds.
The black and white mark are readable on their own, but the contrast improves when used together which makes the barcodes easier to read. Barcode readability is particularly affected by the surface finish.
Mirror finish material can have a large variation in reflected light as the viewing angle changes, which can make the barcode difficult to read at certain angles, whilst brushed material is more uniform. Adding both black and white marks to the positive and negative of a barcode helps to increase the reflected light to the barcode scanner with a wider range of viewing angles.
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