Stabilized Red HeNe Laser

Overview
Specs
Stabilized HeNe
HeNe Accessories
Laser Safety
Feedback

Key Specifications
Wavelength	632.991 nm (Vacuum)
Stabilized Power	>1.2 mW
Polarization	Linear >1000:1
Mode Structure	TEM₀₀ > 99%
Beam Diameter	0.65 ± 0.05 mm
Beam Divergence	1.4 ± 0.2 mrad
Beam Drift During Warm Up	<0.2 mrad
Long-Term Beam Drift^a	<0.02 mrad
Power Input	AC Universal 100 - 240 VAC, 50 - 60 Hz
Lifetime (Typ.)^b	25,000 h
Time to Lock^c	<15 Minutes, Typical
Temperature Range to Maintain Lock	15 - 30 °C
Stabilization Specifications
Output Frequency Stability in Frequency Stabilized Mode	1 Minute 1 Hour 8 Hours	±1 MHz ±2 MHz ±3 MHz
Output Intensity Stability in Intensity Stabilized Mode	1 Minute 1 Hour 8 Hours	±0.1% ±0.2% ±0.3%

Specified after the laser is fully stabilized (after ~1 hour of warm up).
Laser lifetime is defined as the usage time required before the laser output power drops to 50% of the specified output power.
Time for a typical HeNe to stabilize at an ambient temperature of 25 °C.

This laser is shipped with a power supply with a universal voltage input.
Stabilized HeNe Mechanical Drawing

Click for Dimensions

Features

Center Wavelength: 632.991 nm
Offers Two Stabilization Modes: Frequency or Intensity
Output Power > 1.2 mW
Beam Diameter: 0.65 ± 0.05 mm
Linearly Polarized Output

Thorlabs' Stabilized Helium Neon Laser, with a center wavelength of 632.991 nm, allows for either frequency or intensity stabilization, necessary for many spectroscopy, interferometry, and wavemeter applications. In frequency-stabilized mode, the laser will keep its lasing frequency (i.e., wavelength) constant, while in intensity-stabilized mode, the laser will keep its output power constant. For more details on the stabilization modes, please see the Stabilized HeNe tab. Under normal operating conditions, the lifetime of the HRS015B will be around 25,000 hours. The laser’s output is linearly polarized, with the polarization axis marked by a laser engraved line on the laser’s front face.

The graphs below show the stability of the laser in intensity-stabilized mode and frequency-stabilized mode. As seen in the graph on the left, the HRS015B laser's power stabilizes significantly in less than 15 minutes of operation in intensity-stabilized mode and then reaches the final stabilized value in ~1 hour. If the power to the laser needs to be cycled after reaching stabilization in frequency-stabilized mode, the typical time to relock the laser is ~5 min, as shown in the graph on the right. Please note that the relock time depends on the shut down period as the laser will continue to cool while the power is off. Switching between these modes can be accomplished using the switch on the side of the laser housing, as seen in the Stabilized HeNe tab.

The laser is housed in a cylindrical tube, which can be conveniently mounted in a V-clamp mount such as Thorlabs' C1513 Kinematic Mount. The Ø1.77" tube is also compatible with our HCM2 HeNe Mount for 60 mm Cage Systems, as pictured above. For details on our assortment of HeNe accessories, please see the HeNe Accessories tab. The front bezel of this stabilized laser is internally SM1 (1.035"-40) threaded for compatibility with any of Thorlabs' SM1-threaded components. The front face also includes an integrated beam stop and an industry-standard 4-40 tapped hole pattern compatible with our SM05AHN SM05-Threaded Adapter and HCL FiberPort Adapter.

Please note that back reflections into the laser aperture will impair the ability of the control loop to stabilize the frequency or intensity of the laser. Furthermore, large amounts of back reflections can potentially disturb the population inversion of the laser, rendering it unable to lase properly. For instances where back reflections cannot be avoided, Thorlabs recommends using an optical isolator (for example, Item # IO-2D-633-VLP). Additionally, due to the significant ASE background, a bandpass filter should be used for precision measurements.

Thorlabs also offers a 1532.8323 nm Frequency-Locked Laser that can be used as a wavelength reference source.

Click for Details
Click Here for Raw Data
The plot above shows the power fluctuations over an eight hour period in intensity-stabilized mode after a cold start. The fluctuations above represent the percent difference from the average power over the last four hours of measured data. Click on the graph to see a comparison between the power fluctations of the HRS015B and those of the former model.

Click to Enlarge
Click Here for Raw Data
The plot above shows the fluctuation in frequency over five hours of operation in frequency-stabilized mode. The fluctuations above represent the difference from the average frequency over the 5 hour period. To see the above data presented as absolute wavelength over time, click here.

Specifications
Wavelength		632.991 nm (Vacuum)
Stabilized Power		>1.2 mW
Unstabilized Power		1.2 mW to 2.7 mW
Polarization		Linear, >1000:1
Mode Structure		TEM₀₀ > 99%
Beam Diameter		0.65 ± 0.05 mm
Beam Divergence		1.4 ± 0.2 mrad
Beam Drift During Warm Up		<0.2 mrad
Long-Term Beam Drift^a		<0.02 mrad
Noise (30 Hz to 10 MHz)		<1% rms (Max)
Time to Lock^b		<15 Minutes (Typical)
Temperature Range to Maintain Lock		15 - 30 °C
Power Input		AC Universal (100 - 240 VAC, 50 - 60 Hz)
CDRH/CE Classification		IIIa/3R
Lifetime^c		25,000 h (Typical)
Dimensions	Diameter	1.77" (45.0 mm)
Dimensions	Length	11.66" (296.1 mm)
Weight		600 g

Specified after the laser is fully stabilized (after ~1 hour of warm up).
Time for a typical HeNe to stabilize at an ambient temperature of 25 °C.
Laser lifetime is defined as the usage time required before the laser output power drops to 50% of the specified output power.

Stabilization Specifications
Frequency Stabilized Mode
1 Minute	±1 MHz
1 Hour	±2 MHz
8 Hours	±3 MHz
Intensity Stabilized Mode
1 Minute	±0.1%
1 Hour	±0.2%
8 Hours	±0.3%

This laser is shipped with a power supply with a universal voltage input.
Stabilized HeNe Mechanical Drawing

Click for Dimensions

Stabilized HeNe Lasers

Stabilized HeNe lasers offer the ability to change between two modes of operation: frequency and intensity stabilization.

Stabilization System Schematic
Stabilization Feedback Mechanism Schematic

Frequency Stabilization Mode
The frequency stabilization mode will balance the intensity of two modes under the gain curve in order to keep the frequency of the laser stable. The tube length is specifically chosen to only allow two cavity modes at the output. The polarization states of the modes are orthogonal (i.e. one will be s-polarized and the other will be p-polarized). Using a polarizing beamsplitter, one of the modes is directed to a photodetector, while the remaining mode passes through a second beamsplitter where 5% of the output is reflected to a second photodetector, as shown in the schematic above. An error signal generated by the two photodetectors is used to control a heater wrapped around the glass tube. The heater causes the tube to expand and contract as necessary to stabilize the frequency. The frequency stabilization mode also delivers some intensity stability.

Click to Enlarge
The switch on the side of the laser housing controls the stability mode.

Since our stabilized HeNe features a single mode output, the coherence length is increased to hundreds of meters.

Intensity Stabilization Mode
The intensity stabilization mode will stabilize the intensity of the output beam. This mode operates on the same principle as frequency stabilization; however, only one of the photodectectors is used to generate the feedback error signal to control the heater. The intensity stabilization mode also delivers some frequency stability.

On Thorlabs' HRS015B Stabilized HeNe, either mode can be quickly selected by adjusting the toggle switch (shown to the right) into the desired position. Allow the laser up to 2 minutes to stabilize after the mode has been switched.

Protect Against Back Reflections
Please note that back reflections into the laser aperture will impair the ability of the control loop to stabilize the frequency or intensity of the laser. Furthermore, large amounts of back reflections can potentially disturb the population inversion of the laser, rendering it unable to lase properly. For instances where back reflections cannot be avoided, Thorlabs recommends using an optical isolator (for example, Item # IO-2D-633-VLP). Additionally, due to the significant ASE background, a bandpass filter should be used for precision measurements.

FiberPort and Thread Adapters

Click for Details

Adapters for Standard Cylindrical HeNe Lasers^a

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

HCM2 Cage Mount

Click to Enlarge

The HCM2 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 HCM2 provides ±1.0 mm of coarse X and Y adjustment, and is compatible with Ø1/2" and Ø1" posts.

Large V-Clamp Mounts

Click to Enlarge

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.

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

Thorlabs recommends the use of safety eyewear whenever working with laser beams with non-negligible powers (i.e., > Class 1) 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	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 are limited to 5 mW of output power in this class.
3B	Class 3B lasers are hazardous to the eye if exposed directly. However, diffuse reflections are not harmful. Safe handling of devices in this class includes wearing protective eyewear where direct viewing of the laser beam may occur. In addition, laser safety signs lightboxes should be used with lasers that require a safety interlock so that the laser cannot be used without the safety light turning on. Class-3B lasers must be equipped with a key switch and a safety interlock.
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

Posted Comments:

user (posted 2019-04-03 18:49:32.97)

hrs015b 这款激光器是不是单纵模的？

YLohia (posted 2019-04-03 11:38:00.0)

Hello, thank you for contacting Thorlabs. One of our Technical Support representatives (techsupport-cn@thorlabs.com) from our China office will contact you directly.

yur-yulya (posted 2016-08-17 10:40:27.19)

I am a little confused with the Time to Lock parameter. Could you explain what does it mean? Is it the time of stabilization, warm-up time?

jlow (posted 2016-08-17 10:26:04.0)

Response from Jeremy at Thorlabs: That's the time for the laser to stabilized.

vicekam (posted 2014-06-23 05:05:56.737)

Hello. Could you provide the information about a month freq. stability and a lifetime of a HRS015 HeNe laser? Thanks.

jlow (posted 2014-08-05 01:40:19.0)

Response from Jeremy at Thorlabs: We do not have test data for the month-long frequency stability of the HRS015 at the moment. The lifetime of the HRS015 should be around 10k to 20k hours under normal operating conditions.

user (posted 2013-02-23 22:10:10.023)

Would you happen to know the coherence length of the HeNe in frequency and intensity stabilized modes?

tcohen (posted 2013-03-06 14:47:00.0)

Response from Tim at Thorlabs: Our stabilized HeNe has only two longitudinal modes. As one is picked off by the PBS to be used for feedback control, it is single longitudinal mode. The linewidth has not been directly measured, but we estimate the coherence length to be >100m. We will look at testing to quantify this in the future.

cdaly (posted 2012-11-30 16:24:17.777)

Response from Chris at Thorlabs: Thank you for using our feedback feature. We are unable to provide 2010 SolidWorks files directly as the version we use for design (2012) restricts us from creating backwards compatible files, but we do have Step files available for download as well. These files can be opened in SolidWorks 2010 and then saved as an .sldprt file, which will give you the format you require.

xiaoqiang026403 (posted 2012-11-29 02:19:59.497)

I use SolidWorks 2010,but some of your products' Drawing and Documents (SolidWorks) are opened by SolidWorks 2012. Could you send me the HRS015 SolidWorks Documents in version 2010?

tcohen (posted 2012-05-23 09:28:00.0)

Response from Tim at Thorlabs: Thank you for your feedback! We will test this and update you with the data soon.

denis.joyeux (posted 2012-05-22 11:01:45.0)

Please could you provide informations on the beam pointing stability (amplitude ans spectrum) ? This is almost always lacking in stabilized HeNe specs. Thank you.

tcohen (posted 2012-04-12 11:16:00.0)

Response from Tim at Thorlabs to Arjan: Thank you for your feedback. This should not alter the performance of the HeNe or the electronics. The produced magnetic field would need to be a lot stronger to affect the laser. Things that could alter the performance would be any back reflection into the cavity when setting up your isolator or too much mechanical pressure on the tube during mounting.

a.j.h.meskers (posted 2012-04-12 07:00:28.0)

Dear Sir/Madam, The frequency stability mode of this laser is exactly what I need for my project but I'm wondering about the following. In my setup I have back-reflections that I eliminate using an optical isolator (IO-3D-633-VLP). Will this laser be affected in operation by the magnetic field originating from this isolator when I locate it almost completely to the front of this laser tube? (of course not the bare tube, but the laser housing as it is) I look forward to your answer. Kind regards, Arjan Meskers

bdada (posted 2012-03-15 10:35:00.0)

Response from Buki at Thorlabs to graciana.puentes: Thank you for participating in our feedback forum. Unfortunately, we do not have HeNe lasers with power output at 100mW. We do have some laser diodes with output of 100mW or higher and we have contacted you to see if a laser diode may be a suitable alternative for your application. For your reference, below is a link to our selection of laser diodes: http://thorlabs.com/navigation.cfm?Guide_ID=2164

graciana.puentes (posted 2012-03-12 05:08:40.0)

Hi, We are looking for a HeNe laser with 100mW power, or more. Is this available at Thorlabs? Thanks Graciana Puentes

jjurado (posted 2011-03-31 11:34:00.0)

Response from Javier at Thorlabs to Ted Doiron: Thank you very much for your interest in our products. The current lead time for the HRS015 stabilized HeNe laser is 4-5 weeks.The price is $4,400.00. I will contact you directly with a formal quotation.

doiron (posted 2011-03-30 15:57:03.0)

What is the price and delivery of a stabilized HeNe (633 nm) laser? Thanks, ted doiron

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