Silver coated laser mirror LS 20 Si - 20 x 20 x 2 mm

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: Dielectric mirrors vs. metallic mirrors – what are the differences?

Metallic mirrors (aluminium, silver, gold): reflection via a thin metal coating. Typically up to&gt;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 &gt; 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 &gt; 96–98 % reflectivity in the 400–700 nm range.

Q: What is the aperture of an optic?

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.

Q: What does the focal length of a lens mean?

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.

Q: What is an AR coating (anti-reflective)?

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 &lt; 0.5 % per interface. For a lens with two interfaces that means 92 % transmission uncoated vs. &gt; 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.

Q: What is a collimator and what does it do?

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.

LS 20 Si: Silver front-surface mirror, 20 × 20 × 2 mm, with a protective coating. Wavelength range 300–1500 nm, reflectance typically > 98%—also suitable for IR.

€26.18

Product number: LS 20 Si

Silver coated laser mirror LS 20 Si - 20 x 20 x 2 mm

Silver Laser Mirror 20 × 20 × 2 mm – LS 20 Si: High-quality silver front-surface mirror with a protective coating—the silver coating extends the usable wavelength range to 300–1500 nm, making it ideal for IR applications as well.

Dimensions: 20 × 20 × 2 mm
Silver coating with protective layer
Wide bandwidth 300–1500 nm, reflectance typically > 98%

Technical Specifications:

Wavelength range	300–1,500 nm
Minimum reflectance	> 97%
Typical reflectance	> 98%
Dimensions	20 x 20 x 2 mm

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.

Dielectric mirrors vs. metallic mirrors – what are the differences?

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.

What is the aperture of an optic?

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.

What does the focal length of a lens mean?

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.

What is an AR coating (anti-reflective)?

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.

What is a collimator and what does it do?

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.