How Do Laser Barcode Scanners Work?

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Did you know that laser barcode scanners can read barcodes with pinpoint accuracy, even from up to 35 feet away?

With the laser barcode scanner market expected to reach USD 12.15 billion by 2031, their significance in various industries is clear.

Whether you’re considering buying a barcode scanner or just want to understand how these devices work, this quick guide is here to help.

In this guide, we will explore laser barcode scanners. We will explain what they are, how their components work, and their key advantages and applications.

We will also share a buying guide and offer troubleshooting help.

What is a Laser Barcode Scanner?

A laser barcode scanner works by shining a laser on a barcode and reading the light that reflects back. The scanner decodes the information by measuring how the light bounces off the bars and spaces.

Bars are dark (usually black) and bounce back less light. The spaces are light (usually white) and bounce back more light.

Laser barcode scanning is one of the most accurate methods for reading barcodes. These scanners can read from just a few inches up to 30 feet away.

You’ll find them in retail, logistics, and many other industries, helping with tasks like managing inventory, processing sales, and tracking products.

Inside a Laser Barcode Scanner: Components and Working

A laser barcode scanner uses optics, electronics, and mechanics to read barcodes. A laser barcode scanner’s main components are a laser diode, prism, photodiode, analog-to-digital converter and decoder.

Laser Diode and Lens

The laser diode in a barcode scanner emits a beam of light, generally in the red spectrum, with a wavelength of around 650 nanometres.

This beam passes through a lens that adjusts its width and focus to form a scanning line which moves across the barcode to illuminate the bars and spaces.

The scanner’s lens ensures that the light reflects back at the right angle so that the receiving photodiode can capture the reflected signal.

The laser diode of a typical barcode scanner emits a beam with a power output ranging between 0.5 to 1 milliwatt (mW).

Rotating Mirror or Prism

After passing through the lens, the laser beam strikes a rotating mirror or a prism. These are made of borosilicate or fused silica and may also have optical coatings to improve reflectivity and wear. Industrial laser barcode scanners have gold or aluminium coatings.

The rotating mirror or prism directs the beam across the barcode in a sweeping motion.

The oscillating mirror typically oscillates at 30 to 100 times a second. In some scanners, a multi-faceted prism is used to redirect the beam at multiple angles.

The rapid movement of the beam ensures the barcode is scanned multiple times in different positions, improving the chance of a successful read even if the barcode is damaged, poorly printed, or the ambient light is low.

Some laser barcode scanners have diodes for lighting up the barcode.

Photodiode

As the laser sweeps across the barcode, it hits the black bars and white spaces differently. The black bars absorb most light, while the white spaces reflect it to the scanner.

Before reaching the photodiode, the reflected light passes through optical filters to block most ambient light, ensuring only the barcode’s reflection is measured.

The photodiode is usually made from silicon, which is sensitive to the laser’s wavelength. It converts the reflected light into electrical signals, with the strength of these signals changing based on the barcode’s dark and light areas.

The scanner uses a system of beam-splitting optics or polarising filters to prevent interference between the emitted laser and the reflected light.

Analog-to-Digital Conversion

Once the analogue signal is generated, it must be converted into digital form for processing. This conversion is performed by the analogue-to-digital (A/D) converter.

The A/D converter samples these continuous signals at a high rate, often in the range of several kilohertz to megahertz, depending on the system’s scanning speed and resolution.

The sampling rate is at least twice the highest frequency in the signal to prevent aliasing, where the digital signal inaccurately represents the analogue one or vice versa.

In barcode scanners, the A/D converter typically operates with a resolution of 8 to 12 bits, allowing it to differentiate between 256 to 4096 light intensity levels.

Once sampled, the A/D converter quantises the signal, assigning discrete values to the varying intensities. This process, called binarisation, translates the varying light intensities into a digital binary code, which is then sent to the decoder.

Decoder

The digital signals are sent to the decoder, which processes the binary data and translates it into barcode information.

The decoder applies algorithms to interpret the binary patterns, matching them to standard barcode formats such as UPC, EAN, or Code 128. These algorithms identify the start and stop sequences, check for errors, and apply the correct barcode format.

The decoded data is then transmitted to the connected system, providing information like product codes or inventory numbers. This data is used for tasks like updating stock, processing transactions, or tracking items in logistics systems.

Safety Considerations

Laser barcode scanners use class 1 and class 2 lasers.

Class 1 lasers are safe under all conditions including direct eye exposure. Fixed-position scanners, like those found at retail checkout counters, often use Class 1 lasers.

The output of class 2 lasers is around 1 milliwatt and are also considered safe for normal use. Handheld barcode scanners commonly use Class 2 lasers.

In Australia, the European Union (EU), the United Kingdom (UK), and New Zealand, safety standards for laser products are based on the International Electrotechnical Commission (IEC) 60825-1 standard.

In the United States, laser barcode scanners are regulated by the Food and Drug Administration’s (FDA) Center for Devices and Radiological Health (CDRH).

Laser barcode scanners work because they deliver results fast and with precision. Here’s what makes them effective:

Accuracy: With a typical error rate of less than 1 in 3 million scans, laser scanners are reliable for tasks like inventory management and point-of-sale systems.
Speed: They process around 100 to 500 scans per second, making them a go-to for high-traffic areas like supermarkets and warehouses.
Range: Laser scanners can read barcodes from distances up to 30 feet (9 metres), depending on the model and barcode size. This makes them useful in warehouses and manufacturing plants where items are not always within arm’s reach.
Barcode Compatibility: They can scan a wide variety of barcode types, from UPC codes on retail products to dense Code 128 barcodes used in logistics.

Data backs up their use across industries, from retail to supply chain management. For more insights, check out this article.

Limitations of Laser Barcode Scanners

Laser barcode scanners are reliable for reading 1D barcodes, but they come with specific limitations:

1D Only: These scanners can’t read 2D barcodes, such as QR codes or Data Matrix codes. 2D barcodes are becoming more common across industries for tracking and data storage, which is limiting the use of the scanner’s use in modern applications.
Barcode Quality Issues: Laser scanners struggle with poorly printed or damaged barcodes. A damaged or low-contrast barcode, or one that is distorted or partially missing, can lead to misreads or no-reads, slowing down workflows.
Reflective Surfaces: Laser scanners face challenges with reflective surfaces like glossy packaging. Reflections can create high exposure areas that interfere with the laser’s ability to read the barcode accurately. This is a common issue in retail or manufacturing environments where packaging often has shiny surfaces.

These factors should be considered when deciding whether a laser scanner is suitable, especially for industries dealing with diverse barcode types and real-world conditions where barcodes may not always be perfect.

Laser Barcode Scanner Troubleshooting

Laser barcode scanners are reliable tools, but issues can arise that impact their performance. Understanding common problems and their solutions can help maintain the efficiency of your scanner. Here are some unique insights based on research:

Scanner Not Powering On

Check Power Supply: Verify that the power source is functioning. For battery-operated scanners, ensure the battery is charged and correctly installed.
Inspect Connections: Ensure all cables are securely connected and undamaged. Loose or damaged cables can prevent the scanner from powering on.

Scanner Not Reading Barcodes

Barcode Quality: Check for damage or poor printing. Barcodes with low contrast between the bars and spaces can cause readability issues. Linear barcodes typically require a contrast ratio of 80% or higher to be readable by laser scanners .
Lens Cleanliness: Clean the scanner lens to remove dust, dirt, or smudges that can obstruct the laser beam.
Distance and Angle: Hold the scanner at the recommended distance and angle from the barcode. Proper positioning is crucial for accurate reading.

Inconsistent Scanning

Environmental Lighting: Excessive lighting or glare can interfere with scanning. Adjust the lighting conditions or relocate to reduce glare. LED lighting can cause interference; consider adjusting the frequency of the lights or using filters to minimise this issue.
Scan Speed: Avoid moving the scanner too quickly. Allow sufficient time for the scanner to read the barcode properly.
Configuration Settings: Check and reset the scanner’s settings if necessary. Incorrect configurations can impact performance.

Connection Issues with Computer/System

USB/Serial Port: Ensure the scanner is correctly connected to the computer or POS system. Try different ports if needed.
Driver and Software: Install the latest drivers and software from the manufacturer’s website. Outdated or missing drivers can cause connection problems.
Compatibility: Verify compatibility with your operating system and software to prevent connectivity issues.

Scanner Beeping but Not Scanning

Error Codes: Refer to the user manual for beeping patterns indicating specific errors. Understanding these codes can help diagnose the problem.
Decode Settings: Ensure the scanner is configured to read the correct barcode type. Some scanners need to be programmed for specific barcode types.
Firmware Updates: Check for and install firmware updates from the manufacturer. Updates can resolve bugs and improve functionality.

Overheating

Usage Environment: Use the scanner in an appropriate environment. Avoid excessive heat or direct sunlight.
Ventilation: Ensure proper ventilation to prevent overheating. Do not block the scanner’s ventilation slots.
Rest Periods: Allow the scanner to cool down if it overheats. Continuous use without breaks can lead to overheating.

Scanner Producing Incorrect Data

Configuration and Settings: Verify that the scanner’s settings match the required output format. Incorrect settings can lead to misinterpreted data.
Test with Known Barcodes: Use barcodes known to produce correct data to determine if the issue is with the scanner or the barcodes.
Firmware and Software: Ensure both are up-to-date to avoid compatibility issues and enhance performance.

Factors to Consider When Buying a Laser Barcode Scanner

Choosing the right laser barcode scanner for your business involves several important factors. These factors ensure that the scanner you select meets your specific needs and enhances operational efficiency. Here are some key points to consider:

Scanning Range: Determine the distance at which the scanner can read barcodes. This is crucial for environments where items may not be easily accessible.
Durability: Consider the scanner’s build quality, especially if it will be used in harsh environments like warehouses or manufacturing plants.
Compatibility: Ensure the scanner is compatible with your existing systems and software to avoid integration issues.

Conclusion

Laser barcode scanners convert light reflections into data that your system can process. They’re reliable for reading 1D barcodes across various distances, making them a practical choice for industries like retail and logistics. However, they can’t scan 2D barcodes and may struggle with damaged or reflective barcodes.

If you’re in the market for a laser scanner, Triton Store has a range of options. For long-range needs, the Zebra MC3300 is a solid choice. The Zebra MC9300 handles tough environments, and the Honeywell CK65 is ideal for heavy-duty warehouse work.