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Description

Cross line generating optics - Laser cross line Generator 5 to 120 degree

Cross Optic for Laser Diodes: A small plastic lens for generating a laser crosshair, which is placed in front of the laser output—for converting a dot or line laser into a laser crosshair.

Technical Specifications

Material: Acrylic
Diameter: approx. 8 mm
Laser power: up to approx. 1 W

Scope of delivery

Plastic lens only, without laser.

Angle

Distance

Line length approx.

5°

1 m

8 cm

15°

1 m

25 cm

25°

1 m

45 cm

45°

1 m

82 cm

55°

1 m

100 cm

75°

1 m

150 cm

90°

1 m

200 cm

120°

1 m

340 cm

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.
Metallic mirrors (aluminium, silver, gold): reflection via a thin metal coating. Typically up to>98 % reflectivity in the visible range. Benefits: broadband (from UV to IR), low cost. Drawbacks: lower power handling, prone to oxidation (especially silver), reflectivity depends on angle of incidence. Dielectric mirrors: reflection via multi-layer glass coatings that reflect through interference. Typically > 99 % reflectivity in the optimized spectral range. Benefits: extremely high reflectivity, high power handling, no oxidation. Drawbacks: narrowband (optimized for a specific wavelength), more expensive. Our LS 50 is a dielectric mirror with > 96–98 % reflectivity in the 400–700 nm range.
The aperture is the usable opening diameter of an optic – the area through which light can enter the lens. Measured in millimetres. A larger aperture collects more light from the source – particularly important for laser diodes with a large emitter (e.g. Nichia NDG7575). Our Colli-LA collimator has a 5 mm aperture, gathering significantly more light than typical 3 mm collimators. Practical effect: brighter, more uniform output beam and less light lost at the diode edge. Related metric: the numerical aperture (NA) describes the ratio of aperture to focal length – and therefore the optic's acceptance angle.
The focal length is the distance from the principal plane of a lens to the focal point, where parallel incoming light rays intersect. It is measured in millimetres (e.g. f = 4 mm on our Colli-LA). For collimators the focal length determines at which distance from the laser diode the lens must be mounted to collimate the beam – ideally the diode emits from the focal plane. Shorter focal lengths (3–4 mm): high aperture, good light gathering, compact – ideal for 12 mm modules. Longer focal lengths (8–20 mm): smaller aperture, less light gathering, but a narrower collimated beam – for long-distance applications.
An AR coating (anti-reflective coating) is a thin, multilayer coating on optical glass surfaces that reduces reflection and increases transmission. At an uncoated glass–air interface typically 4–8 % of the light is lost to reflection. A modern AR coating reduces this to < 0.5 % per interface. For a lens with two interfaces that means 92 % transmission uncoated vs. > 99 % coated. Benefits: higher optical efficiency, less stray light, lower back-reflection load on the laser diode. AR coatings are wavelength-specific – a coating for 532 nm behaves differently at 650 nm. Always check the spectral range of the optic.
A collimator is an optical lens or lens system that converts a divergent light beam into a parallel beam. Essential with laser diodes: the bare diode emits a strongly fanned-out beam; the collimator turns it into a bundled, parallel beam. Construction: usually an aspheric glass lens in an M9 × 0.5 or M12 threaded housing. High-quality collimators feature an AR coating (anti-reflective) for minimal light loss at the interfaces. Key parameters: focal length (typ. 3–6 mm), aperture (typ. 4–8 mm) and the AR coating's spectral range (e.g. 420–680 nm for visible light). Glass collimators are more temperature-stable than cheaper acrylic lenses.
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.
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.
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.
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.
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).
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.
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.
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.