Features

• 632.8 nm Central Wavelength
• Linear or Fluctuating Output Beam Polarization
• Includes External Power Supply
• Packages Available with Integrated Shutters and Remote Interlock Connections

Thorlabs offers an extensive selection of CE compliant 632.8 nm (red) Helium-Neon (HeNe) Lasers with powers from 0.8 mW to 22.5 mW from stock. In addition to the applications listed here, HeNe lasers are widely used in education and as alignment tools due to their excellent beam quality and gas discharge laser characteristics. Depending upon the model, the output beam is either linearly polarized or the polarization state fluctuates over time. When the output polarization is fluctuating over time, any polarization optics in the path (intentional or unintentional) can cause large variations in the output power. Only polarized lasers should be used in applications that involve polarization optics. For a complete discussion of HeNe laser polarization, see our HeNe Laser Tutorial. Due to the significant amplified spontaneous emission (ASE) background, a bandpass filter should be used for precision measurements.

Specifications common to all of the lasers featured on this page are listed in Table 1.1, and model-dependent information is given in Tables G1.5, G2.1, G3.2, G4.2, G5.2, G6.2, and G7.2. All but the self-contained packages feature remote interlock connections and integrated shutters. Please see the Interlock Disassembly tab for integrating the remote interlock connector into an interlock or lab safety system.

For specialized applications, Thorlabs offers a Stabilized Red HeNe Laser, which is capable of either ±2 MHz stabilization in frequency stabilization mode, or ±0.2% power stabilization in intensity stabilization mode.

Laser Safety and Classification

Safe practices and proper usage of safety equipment should be taken into consideration when operating lasers. The eye is susceptible to injury, even from very low levels of laser light. Thorlabs offers a range of laser safety accessories that can be used to reduce the risk of accidents or injuries. Laser emission in the visible and near infrared spectral ranges has the greatest potential for retinal injury, as the cornea and lens are transparent to those wavelengths, and the lens can focus the laser energy onto the retina. 

Safe Practices and Light Safety Accessories

• Laser safety eyewear must be worn whenever working with Class 3 or 4 lasers.
• Regardless of laser class, Thorlabs recommends the use of laser safety eyewear whenever working with laser beams with non-negligible powers, since metallic tools such as screwdrivers can accidentally redirect a beam.
• Laser goggles designed for specific wavelengths should be clearly available near laser setups to protect the wearer from unintentional laser reflections.
• Goggles are marked with the wavelength range over which protection is afforded and the minimum optical density within that range.
• Laser Safety Curtains and Laser Safety Fabric shield other parts of the lab from high energy lasers.
• Blackout Materials can prevent direct or reflected light from leaving the experimental setup area.
• Thorlabs' Enclosure Systems can be used to contain optical setups to isolate or minimize laser hazards.
• A fiber-pigtailed laser should always be turned off before connecting it to or disconnecting it from another fiber, especially when the laser is at power levels above 10 mW.
• All beams should be terminated at the edge of the table, and laboratory doors should be closed whenever a laser is in use.
• Do not place laser beams at eye level.
• Carry out experiments on an optical table such that all laser beams travel horizontally.
• Remove unnecessary reflective items such as reflective jewelry (e.g., rings, watches, etc.) while working near the beam path.
• Be aware that lenses and other optical devices may reflect a portion of the incident beam from the front or rear surface.
• Operate a laser at the minimum power necessary for any operation.
• If possible, reduce the output power of a laser during alignment procedures.
• Use beam shutters and filters to reduce the beam power.
• Post appropriate warning signs or labels near laser setups or rooms.
• Use a laser sign with a lightbox if operating Class 3R or 4 lasers (i.e., lasers requiring the use of a safety interlock).
• Do not use Laser Viewing Cards in place of a proper Beam Trap.

Laser Classification

Lasers are categorized into different classes according to their ability to cause eye and other damage. The International Electrotechnical Commission (IEC) is a global organization that prepares and publishes international standards for all electrical, electronic, and related technologies. The IEC document 60825-1 outlines the safety of laser products. A description of each class of laser is given below:

Class	Description	Warning Label
1	This class of laser is safe under all conditions of normal use, including use with optical instruments for intrabeam viewing. Lasers in this class do not emit radiation at levels that may cause injury during normal operation, and therefore the maximum permissible exposure (MPE) cannot be exceeded. Class 1 lasers can also include enclosed, high-power lasers where exposure to the radiation is not possible without opening or shutting down the laser.
1M	Class 1M lasers are safe except when used in conjunction with optical components such as telescopes and microscopes. Lasers belonging to this class emit large-diameter or divergent beams, and the MPE cannot normally be exceeded unless focusing or imaging optics are used to narrow the beam. However, if the beam is refocused, the hazard may be increased and the class may be changed accordingly.
2	Class 2 lasers, which are limited to 1 mW of visible continuous-wave radiation, are safe because the blink reflex will limit the exposure in the eye to 0.25 seconds. This category only applies to visible radiation (400 - 700 nm).
2M	Because of the blink reflex, this class of laser is classified as safe as long as the beam is not viewed through optical instruments. This laser class also applies to larger-diameter or diverging laser beams.
3R	Class 3R lasers produce visible and invisible light that is hazardous under direct and specular-reflection viewing conditions. Eye injuries may occur if you directly view the beam, especially when using optical instruments. Lasers in this class are considered safe as long as they are handled with restricted beam viewing. The MPE can be exceeded with this class of laser; however, this presents a low risk level to injury. Visible, continuous-wave lasers in this class are limited to 5 mW of output power.
3B	Class 3B lasers are hazardous to the eye if exposed directly. Diffuse reflections are usually not harmful, but may be when using higher-power Class 3B lasers. Safe handling of devices in this class includes wearing protective eyewear where direct viewing of the laser beam may occur. Lasers of this class must be equipped with a key switch and a safety interlock; moreover, laser safety signs should be used, such that the laser cannot be used without the safety light turning on. Laser products with power output near the upper range of Class 3B may also cause skin burns.
4	This class of laser may cause damage to the skin, and also to the eye, even from the viewing of diffuse reflections. These hazards may also apply to indirect or non-specular reflections of the beam, even from apparently matte surfaces. Great care must be taken when handling these lasers. They also represent a fire risk, because they may ignite combustible material. Class 4 lasers must be equipped with a key switch and a safety interlock.
All class 2 lasers (and higher) must display, in addition to the corresponding sign above, this triangular warning sign.

FiberPort and Thread Adapters

FiberPort and Thread Adapters for Self-Contained HeNe Lasers

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The SM1A32 Thread Adapter allows externally SM05-threaded or internally SM1-threaded optomechanics to be attached to the output aperture of the
HNLS008R(-EC)(-JP) or HNLS008L(-EC)(-JP) laser.

The HCL2 Adapter, which features external 5/8"-32 threading, allows a FiberPort coupler to be attached directly to the threaded aperture of our self-contained HeNe lasers or any other 5/8"-32 tapped hole. A slip-plate design allows the position of the fiberport to be shifted and locked to maximize coupling efficiency. FiberPort mounting screws are included.

FiberPort and Thread Adapters for Standard Cylindrical HeNe Lasers^a

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The SM05AHN Thread Adapter allows SM05-threaded components to be attached directly to the front of a HeNe laser and is ideal for enclosing a HeNe beam path using SM05 Lens Tubes.

The HCL FiberPort Adapter allows a FiberPort coupler to be attached directly to the front of a HeNe laser. Both adapters can be attached to the laser via counterbored slots that fit industry-standard M3 and 4-40 four-bolt patterns. The HCL can also be mounted via the internal C-Mount-Threaded (1.00"-32) central bore.

• Note that these adapters are not compatible with the HNL008 Series of Cylindrical HeNe Lasers.

Mounting Adapters

Drop-In Post Clamp

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Figure 3.3  The C174TC is designed specifically for mounting Ø1.74" (44.2 mm) cylindrical lasers to Thorlabs optical posts with 8-32 (M4) taps. A captive screw with a 3/32" (2.5 mm) hex secures the laser in place.

V-Clamp Post Mount

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Figure 3.2  The C1512(/M) and C1513(/M) are designed specifically for fastening Ø0.56" (14 mm) to Ø2" (50 mm) cylindrical lasers to Thorlabs' rigid Ø1.5" Posts. One PM4(/M) Clamping Arm is included with each unit and additional clamping arms can be purchased as needed here.

Post and Cage Mount

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Figure 3.1  The HCM2A(/M) Cage Mount enables integration of a cylindrical HeNe laser with a diameter between 1.74" and 1.77" (44.2 mm and 45.0 mm) into a 60 mm cage system or SM2 (2.035"-40) lens tube system. The HCM2A(/M) provides ±1.0 mm of coarse X and Y adjustment and is compatible with Ø1/2" and Ø1" posts.

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Figure 4.1  Remote Interlock Connector for 100 - 240 VAC Power Supplies 

Interlock Disassembly

Each of Thorlabs' HeNe laser sources includes an external power supply with a remote interlock connector. The interlock connector can be disassembled for integration into an interlock system. The interlock is at AC line potential, so proper care must be taken to use the correct connectors and hardware. Be sure to confirm compatibility between the AC line and the interlock system.

The 100 - 240 VAC external power supply that comes with our cylindrical HeNe lasers uses a simplified interlock connector that includes a black, plastic cover that can be unscrewed. Once unscrewed, the shorting conductor on the connector is removed prior to integration into the interlock system (see Figure 4.1).

Insights into HeNe Lasers

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• HeNe Lasers: Handling and Mounting Guidelines

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HeNe Lasers: Handling and Mounting Guidelines

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Figure 185A  The external housing of HeNe lasers is mechanically coupled to the components of the lasing cavity. Stress applied to the external housing can misalign and potentially fracture lasing cavity components, which can negatively impact the quality and power of the output laser beam (red arrow) or lead to laser failure

1.	High Reflector Optics	7.	Anode
2.	Gas Reservoir	8.	Glass Laser Bore
3.	Outer Housing	9.	Metal Springs that Align and Stabilize Bore
4.	Glass	10.	Potting Compound
5.	Glass-Metal Seal	11.	Cathode
6.	Output Coupling Optics

HeNe lasers should be handled and mounted with care to protect them from damage. 

Never apply a bending force to the laser housing. Stress applied to the laser's external housing can misalign or damage components in the laser cavity. This can:

• Affect the output beam quality.
• Result in reduced output power.
• Affect the beam pointing.
• Cause multimode effects.

Factory packaging protects the HeNe lasers from shocks and vibrations during shipping, but end users directly handle the bare laser housing. Due to this, HeNe lasers are in greater danger of experiencing dangerous stress during handling by the end user.

A result is that the primary cause of damage to HeNe lasers is rough handling after receipt of the laser. In extreme cases, shock and vibrations can shatter or fracture glass components internal to the laser. 

To maintain the optimum performance of your HeNe laser, do not drop it, never use force when inserting it into fixture, and use care when installing it into mounts, securing it using cage components or ring accessories that grip the housing, transporting it, and storing it.

HeNe lasers will provide optimum performance over a long lifetime when they are handled gently.

Date of Last Edit: Dec. 4, 2019