Diode laser module 20mW 635nm BRIGHT RED, adjustable focus, insulated
Collimator:
Glass
Connection type:
Barrel connector
LDM-20-635: 20 mW bright red (635 nm) dot laser module with adjustable collimator. Compact laser diode module for positioning and alignment.
Regular price:
€87.49
Delivery time: In stock
Product number:
LDM-20-635.6
Description
Diode laser module 20mW 635nm BRIGHT RED, adjustable focus, insulated
20 mW Bright Red (635 nm) Laser Spot Module – LDM-20-635: Compact, high-performance laser diode module that projects a sharp laser spot—with an adjustable collimator (focus range approx. 5 cm to infinity). Suitable for highly visible positioning and alignment marks, as well as for integration into devices and machines.
- Bright red laser spot (635 nm) with 20 mW
- Adjustable collimator, focus range approx. 5 cm to infinity
- Laser Class 3B after setup
Technical Specifications
| Laser power: | 20 mW |
| Wavelength / Color: | 635 nm BRIGHT RED |
| Focus range: | approx. 5 cm to infinity |
| Divergence: | typ. <0.7 mrad |
| laser class: | 3B |
| Power supply: | 3–5 VDC / < 100 mA |
| Potential: | Insulated housing |
| Length of connection wires: | Stranded wires approx. 200 mm, hollow plug approx. 200 mm |
| Dimensions: | 12 x 37 mm |
| Temperature range | -15°C to +45°C |
| Service life: | typ. > 25,000 h |
Notes
- Observe the laser class!
- For more information on laser safety, click here.
Properties
| Collimator: | Acrylic, Glass |
|---|---|
| Connection type: | 12-25VDC, 110-230VAC, Barrel connector, Wires |
Which well-known manufacturers of laser diodes exist?
The leading manufacturers of industrial laser diodes: Nichia (Japan) – market leader for green and blue laser diodes, highest efficiency and service life; well-known models include the NDG7575 (1 W green, 520 nm) and the NUBM series (blue). Sharp (Japan) – strong second source for visible wavelengths; models such as GH05C01B9G (1 W green). Osram Opto Semiconductors (Germany) – broad portfolio from 405 to 850 nm. Sony – mainly for display and show applications. Ushio – industrial high-power diodes. For red and infrared the choice is wider; for green and blue Nichia and Sharp are the dominant sources.
How does beam shaping (collimation) of a laser diode work?
A bare laser diode emits a strongly divergent, elliptical beam – the bare diode does not produce a usable spot but rather a fanned-out cone. For practical use the beam must be collimated – reshaped into a parallel, directed beam. Standard solution: a collimator lens directly in front of the diode, mounted in an M9 × 0.5 housing (brass or aluminium). A single-lens optic turns the divergent beam into an approximately parallel beam. On high-quality collimators (e.g. our Colli-LA) we use an aspheric glass lens with AR coating, 5 mm aperture, focal length approx. 4 mm. For especially round beam profiles, correction optics can be added behind the collimator.
Why does a laser diode need a heat sink?
Laser diodes dissipate typically 50–70 % of the electrical power as heat – only a fraction becomes light. A 1 W laser diode therefore generates 1.5–2 W of waste heat in the semiconductor chip. Without a heat sink the junction temperature climbs to critical levels within seconds and the diode fails thermally. Consequences: drastic wavelength shift (red-shifted), efficiency collapse, irreversible destruction. Rule of thumb: every additional 10 °C in junction temperature roughly halves the service life. Practice: mount the diode in a massive metal holder (brass or aluminium), the holder on a heat sink with thermal compound, and add a fan or thermal convection for > 1 W.
What is a constant-current driver for laser diodes?
A constant-current driver is an electronic circuit that regulates the current flowing through a laser diode to an exact value – independent of input voltage and temperature variations. This is necessary because a laser diode's optical output depends linearly on current, not on voltage. A simple voltage supply would, with small temperature or supply fluctuations, lead to large current and therefore optical-output swings – in the worst case destroying the diode. Good drivers offer: constant-current regulation, soft-start, over-temperature protection, ESD protection and often analog/TTL modulation for pulsed operation. Matching drivers are available in our „Laser drivers“ category.
How is a bare laser diode driven correctly?
A bare laser diode needs a constant-current driver – not a simple voltage supply. Reason: the diode has a very steep current/light-output curve. Even 5 % current variation can destroy the diode. Concrete requirements: 1. Constant-current-regulated supply at the operating current specified in the datasheet (e.g. 1.6 A for Nichia NDG7575). 2. Soft-start (no abrupt current jump). 3. Protection against voltage spikes on the supply side. 4. Adequate heat dissipation via a heat sink (typically < 30 °C junction temperature). 5. ESD protection during handling – bare diodes are extremely ESD-sensitive.
What is a TO-9 laser diode?
TO-9 is a standardized package format for laser diodes – a cylindrical metal can with 9 mm diameter. The package contains the laser semiconductor chip, a protective cap with exit window and the electrical pins (typically 3). Benefits: uniform mechanical interface, good heat dissipation through the metal housing, easy integration into sockets and heat sinks. TO-9 is, alongside TO-5 (5.6 mm) and TO-18 (5.6 mm, older), the most common package for high-power laser diodes with > 200 mW. Examples: Nichia NDG7575 (1 W green), Sharp GH05C01B9G (1 W green). A bare TO-9 diode is a pure component without collimator and without driver.
What do „fixed focus“ and „adjustable“ mean?
Fixed focus: the optics are set at the factory to a fixed distance and cannot be changed – typically a point in the range 1–5 m. Benefit: no accidental adjustment possible, stable over the entire service life. Trade-off: cannot be adapted to other distances. Adjustable: the optics sit in an adjustable brass ring at the front of the module and can be focused by the user to any desired distance (5 cm to infinity). After adjustment the optics are secured with thread-locking varnish in the thread. Which variant? Fixed focus for defined series production with constant distance, adjustable for flexible applications and one-off setups.
Which typical applications exist for point lasers?
Industrial alignment: point lasers as a reference for aligning machines, conveyors, roller tracks and light barriers. Distance measurement: as a light source in triangulation sensors for distance and profile measurement. Marking: in research and test setups as precise reference points. Optical test setups: as a light source for beam splitting, diffraction and interference experiments. Workpiece positioning: in production as a reference point for drilling and placement operations. Construction: plumb points, height references, wall alignment (not our domain – we supply industrial quality, not DIY plumb lasers).
Why does a green point laser look brighter than a red one?
The human retina is most sensitive in the green spectral range around 555 nm – that is the peak of the eye's spectral sensitivity. Green laser light at 520 nm sits close to this peak, while red light at 650 nm sits at the edge of visual sensitivity. Specifically: a 5 mW green point laser looks visually about as bright as a 25–35 mW red point laser. Practical effect: at equal perceived brightness, green gives you a lower laser class – Class 2 instead of Class 3R for red. This simplifies safety measures significantly. Trade-off: green laser diodes are more expensive and more temperature-sensitive than red ones.
What is beam divergence and why does it matter?
Beam divergence describes how strongly a laser beam expands with distance. It is measured in milliradians (mrad). Example: a beam with 1 mrad divergence widens by 10 cm over 100 m distance. For point lasers low divergence is desirable – so the dot stays sharp over long distances. Typical values: 0.5–2 mrad after collimation. Influencing factors: emitter size of the laser diode, quality of the collimator optics, wavelength. For our OEM modules the divergence is typically specified in each module's datasheet or optimized at the factory.
What do the laser classes 3R and 3B mean?
Class 3R: increased risk on direct viewing of the beam, but the natural blink reflex usually still provides sufficient protection. Safety goggles are recommended but not strictly required in all cases. Maximum 5 mW in the visible range. Class 3B: direct radiation is hazardous to the eye, but diffuse reflections are usually harmless. Safety goggles are mandatory in the open beam area. Beam enclosure where possible, clear marking of laser areas, training of personnel. Maximum 500 mW. Both classes require a laser safety officer in commercial use.
When to choose a point, line or cross laser?
Point lasers (also called dot lasers) project a sharp spot of light – ideal for precise single-point marking, distance measurement, triangulation and alignment tasks over large distances. Benefit: all the optical power is concentrated at the point, giving very high visibility even at low power. Line lasers project a line – ideal for cutting lines, paths and boundaries. Cross lasers project a cross from two lines – ideal for centring and 2D alignment. Rule of thumb: point for „this spot here“, line for „along this axis“, cross for „centred exactly on this intersection“.