Cross Laser Module, 4 mW, Bright Red, 635 nm

Q: What is the difference between light red (635 nm) and red (650 nm)?

Both wavelengths appear red to the eye, but light red (635 nm) sits closer to the peak sensitivity of the human retina than red (650 nm). Specifically: 635 nm light appears roughly 2× brighter than 650 nm light at the same optical power. Practical effect: a 20 mW light-red module looks visually comparable to a 40 mW red module – with a lower laser class and longer diode service life. Light-red modules are slightly more expensive to manufacture but pay off in brighter environments or where a lower laser class is required.

Q: Glass optics vs. acrylic optics – when which?

Acrylic optics (PMMA plastic): low cost, light, dimensionally stable. Optically very good in standard applications, but temperature-sensitive – the refractive index changes with temperature, shifting the focus when variation exceeds ±5 °C. Perfectly adequate for indoor applications with stable conditions. Glass optics: heavier, more expensive, but temperature-stable. The refractive index stays nearly constant across wide temperature swings. Ideal for: outdoor mounting, unheated halls, machines with large temperature swings (welding, sawmills in summer/winter) and applications needing high repeat accuracy over long periods. Glass optics are available as an optional upgrade on our KLM and LLM modules.

Q: What does &bdquo;stabilized and peak-free power supply&ldquo; mean (cross-line laser)?

Cross-line laser modules contain sensitive laser diodes that can be destroyed within microseconds by voltage spikes and current fluctuations. Stabilized means: constant output voltage under load, no sag during switch-on. Peak-free means: no switching spikes or overshoot on the supply line. Always use a switching power supply with sufficient smoothing or a dedicated laser diode driver. Avoid unfiltered supplies, cheap USB power banks without stabilization, and supplies shared with switching relays or motors. The DC variant of our modules includes integrated reverse-polarity protection.

Q: When is the optional glass collimator worthwhile?

The standard version of our KLM modules ships with an aspheric acrylic lens – sufficient for stable indoor temperatures. With strongly fluctuating operating temperatures (more than ±5 °C variation) the acrylic lens can shift focus – beam width changes and sharpness suffers. The optional three-lens glass collimator is significantly more temperature-stable: glass barely expands, so the focus stays constant. Recommended for: outdoor mounting, unheated halls, machines with large temperature swings (welding, sawmills in summer/winter) and applications needing high repeat accuracy over long periods.

Q: How big is the cross at a given distance?

The cross size scales linearly with distance. With a 90° lens angle on a 12 mm module, 1 m distance gives a cross with roughly 2 m line length per axis. At 2 m distance this doubles to about 4 m per axis. With narrower angles (e.g. 35°) the cross is correspondingly smaller: 0.62 m at 1 m distance. Note: as distance grows the cross gets not only larger but also wider in line width (beam divergence). For especially sharp crosses at a known distance, the focus is adjusted on the module (brass ring at the front).

Q: Which colour for which surface (cross-line laser)?

Red (650 nm): standard choice, lowest cost, sufficient in moderately lit environments. Light red (635 nm): noticeably brighter than 650 nm red at the same power, good visibility on most surfaces. Green (520 nm): appears roughly 5–7× brighter than red – the choice for very bright environments, visible in daylight, large distances or dark surfaces. Blue (450 nm): ideal on wood, vegetation, greenish or yellow surfaces – where red and green get lost in the background. Light blue (488 nm): high contrast on warm-light spectra, a special colour for surfaces such as red-toned woods.

Q: Cross-line laser vs. line laser vs. positioning laser – what are the differences?

Line laser: projects one line – ideal for cutting lines, paths and boundaries. Cross-line laser: projects two perpendicular lines as a cross (90°) – ideal for centring and aligning. Positioning laser with DOE optics: projects a pattern (crosshair, circle, search field, square) through a diffractive optical element – the image has constant brightness across the entire area, but the lines are inherently wider than with classic lens optics. In short: line for straight markings, cross-line laser for precise centring with sharp lines, DOE positioning laser for evenly bright patterns including the outer areas.

Q: What is a cross-line laser?

A cross-line laser (also called cross hair laser) projects two perpendicular lines (90°) – a true line cross – onto a surface. Unlike a positioning laser with DOE optics, the cross here is generated by two classic cylindrical lenses. Benefits: sharp, bright lines across the full image width, daylight-capable – good visibility even in daylight and bright environments. Typical applications are workpiece centring on CNC, sawing and drilling machines, microscope reference crosses, inspection stations and operator guidance at manual workstations. Cross-line laser modules are available in red, light red (635 nm), green, blue and light blue – each with adjustable focus.

Cross laser module BRIGHT RED 4 mW, adjustable focus

Cross Laser Module 4 mW Bright Red (635 nm) – KLM-4-635: Compact, high-performance cross laser module that uses a cross optic to project two perpendicular lines as a bright red laser cross. The affordable entry-level module for short-distance positioning and alignment tasks. Focus and line position can be adjusted directly on the module.

Bright red laser cross (635 nm) with 4 mW
Numerous cross sizes selectable via selectable cross optics
Adjustable focus (line width) and line position
Compact 12-mm housing for machine integration

Electrical Connection

Standard: In the standard version, power is supplied via two red/black wires, each approximately 20 cm long. Please note that the laser module housing is at positive potential.

Hollow connector: The 230 V version features a power cable with a round 5.5/2.1 hollow connector.

12–25 V Version: The laser modules are equipped with a flexible connection cable. If you select the 24 V version, a small adapter is heat-shrunk onto the supply cable. The ends are open and fitted with wire end ferrules, allowing them to be connected directly to an existing power supply or a busbar. Reverse polarity protection is built-in. Please note that the laser module housing is at positive potential.

Technical Specifications

Laser Power	4 mW
Wavelength/Color	635 nm Bright red
Projection angle	selectable
Focus range	Approx. 5 cm to infinity
Minimum line width	<1 mm at close range
Divergence	typ. <1 mrad
Power supply	3–4 VDC / < 50 mA
Power supply	24 VDC / < 50 mA
Potential	+ on the housing
Length of connection cables	Stranded wires approx. 150 mm, hollow plug approx. 200 mm, flexible cable 100 cm
Laser class after setup	Class 1
Dimensions	12 x 35–42 mm
Temperature range	- 10°C to +45°C
Service life	typ. > 25,000 h

Cross Size and Line Width

The size of the projected cross is determined by the selected cross angle. The following angles are available for the KLM-4-635:

Angle	Distance	Cross size approx.
5°	1 m	8–9 cm
15°	1 m	25 cm
25°	1 m	40 cm
45°	1 m	85 cm
55°	1 m	100 cm
75°	1 m	170 cm
100°	1 m	230 cm

The line width (focus) is adjusted directly on the module.

Notes

Observe the laser class!
For more information on laser safety, click here.
Stabilized, peak-free power supply!

Options

Hollow-pin connector; direct operation via plug-in power supply possible
M8 connector with custom cable length
Glass collimator for improved stability during temperature fluctuations
Various mounts available as accessories

Downloads / Links

Collimator:	Acrylic, Glass
Connection type:	12-25VDC, 110-230VAC, Barrel connector, Wires
Cross angle:	5 deg, 15 deg, 55 deg, 75 deg, 90 deg

What is the difference between light red (635 nm) and red (650 nm)?

Both wavelengths appear red to the eye, but light red (635 nm) sits closer to the peak sensitivity of the human retina than red (650 nm). Specifically: 635 nm light appears roughly 2× brighter than 650 nm light at the same optical power. Practical effect: a 20 mW light-red module looks visually comparable to a 40 mW red module – with a lower laser class and longer diode service life. Light-red modules are slightly more expensive to manufacture but pay off in brighter environments or where a lower laser class is required.

Glass optics vs. acrylic optics – when which?

Acrylic optics (PMMA plastic): low cost, light, dimensionally stable. Optically very good in standard applications, but temperature-sensitive – the refractive index changes with temperature, shifting the focus when variation exceeds ±5 °C. Perfectly adequate for indoor applications with stable conditions. Glass optics: heavier, more expensive, but temperature-stable. The refractive index stays nearly constant across wide temperature swings. Ideal for: outdoor mounting, unheated halls, machines with large temperature swings (welding, sawmills in summer/winter) and applications needing high repeat accuracy over long periods. Glass optics are available as an optional upgrade on our KLM and LLM modules.

What does „stabilized and peak-free power supply“ mean (cross-line laser)?

Cross-line laser modules contain sensitive laser diodes that can be destroyed within microseconds by voltage spikes and current fluctuations. Stabilized means: constant output voltage under load, no sag during switch-on. Peak-free means: no switching spikes or overshoot on the supply line. Always use a switching power supply with sufficient smoothing or a dedicated laser diode driver. Avoid unfiltered supplies, cheap USB power banks without stabilization, and supplies shared with switching relays or motors. The DC variant of our modules includes integrated reverse-polarity protection.

When is the optional glass collimator worthwhile?

The standard version of our KLM modules ships with an aspheric acrylic lens – sufficient for stable indoor temperatures. With strongly fluctuating operating temperatures (more than ±5 °C variation) the acrylic lens can shift focus – beam width changes and sharpness suffers. The optional three-lens glass collimator is significantly more temperature-stable: glass barely expands, so the focus stays constant. Recommended for: outdoor mounting, unheated halls, machines with large temperature swings (welding, sawmills in summer/winter) and applications needing high repeat accuracy over long periods.

How big is the cross at a given distance?

The cross size scales linearly with distance. With a 90° lens angle on a 12 mm module, 1 m distance gives a cross with roughly 2 m line length per axis. At 2 m distance this doubles to about 4 m per axis. With narrower angles (e.g. 35°) the cross is correspondingly smaller: 0.62 m at 1 m distance. Note: as distance grows the cross gets not only larger but also wider in line width (beam divergence). For especially sharp crosses at a known distance, the focus is adjusted on the module (brass ring at the front).

Which colour for which surface (cross-line laser)?

Red (650 nm): standard choice, lowest cost, sufficient in moderately lit environments. Light red (635 nm): noticeably brighter than 650 nm red at the same power, good visibility on most surfaces. Green (520 nm): appears roughly 5–7× brighter than red – the choice for very bright environments, visible in daylight, large distances or dark surfaces. Blue (450 nm): ideal on wood, vegetation, greenish or yellow surfaces – where red and green get lost in the background. Light blue (488 nm): high contrast on warm-light spectra, a special colour for surfaces such as red-toned woods.

Cross-line laser vs. line laser vs. positioning laser – what are the differences?

Line laser: projects one line – ideal for cutting lines, paths and boundaries. Cross-line laser: projects two perpendicular lines as a cross (90°) – ideal for centring and aligning. Positioning laser with DOE optics: projects a pattern (crosshair, circle, search field, square) through a diffractive optical element – the image has constant brightness across the entire area, but the lines are inherently wider than with classic lens optics. In short: line for straight markings, cross-line laser for precise centring with sharp lines, DOE positioning laser for evenly bright patterns including the outer areas.

What is a cross-line laser?

A cross-line laser (also called cross hair laser) projects two perpendicular lines (90°) – a true line cross – onto a surface. Unlike a positioning laser with DOE optics, the cross here is generated by two classic cylindrical lenses. Benefits: sharp, bright lines across the full image width, daylight-capable – good visibility even in daylight and bright environments. Typical applications are workpiece centring on CNC, sawing and drilling machines, microscope reference crosses, inspection stations and operator guidance at manual workstations. Cross-line laser modules are available in red, light red (635 nm), green, blue and light blue – each with adjustable focus.