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High-Power MicroSpot™ Focusing Objectives for Nd: YAG Lasers


  • 5X, 10X, 20X, and 50X Versions at 532 nm and 1064 nm
  • Better than 95% Transmission Within Design Spectral Region
  • Damage Threshold of 15 J/cm2 for 532 nm and 20 J/cm2 for 1064 nm

LMH-5X-1064

LMH-10X-1064

LMH-20X-532

LMH-50X-532

Related Items


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Features

  • Designed for High-Power Industrial Nd:YAG Lasers
  • All Fused Silica Lens Design
  • RMS-Threaded (0.800"-36) Housing
  • Damage Threshold of ≥15.0 J/cm2 for 10 ns Pulses @ 20 Hz (See the Damage Thresholds Tab for More Details)

Applications

  • Laser Engraving
  • Laser Cutting
  • 2D and 3D Photolithography
  • 3D Printing
  • Stealth Dicing
  • Laser Welding
Zemax Files
Click on the red Document icon next to the item numbers below to access the Zemax file download. Our entire Zemax Catalog is also available.

Click to Enlarge
The LMH-50X-1064 features two scales on its red correction collar for cover slips of either SiC or Fused Silica.

Thorlabs' High-Power Nd:YAG MicroSpot™ Focusing Objectives are designed to focus on-axis Nd:YAG laser beams to a diffraction-limited spot. They offer a damage threshold of 15 J/cm2 at 532 nm or 20 J/cm2 1064 nm (10 ns, 20 Hz pulses). The RMS threading on each of our MicroSpot objectives allows for easy integration into existing systems, and their robust housing and fused silica lens design is built to hold up to consistent industrial or laboratory use.

Focusing objectives can be used in a variety of applications where intense optical power is necessary, such as laser cutting or engraving. At lower powers, focused laser light can be used for wafer inspection or to activate special types of photoresist in photolithography. Because all the objectives on this page have a limited field of view, laser scanning should be performed by moving either the sample or the objective. When incorporating these objectives into a system, note that the labeled magnifications of these objectives are calculated assuming the objective is being use with a 200 mm focal length tube lens.

The LMH-50X-532 and LMH-50X-1064 objectives are each equipped with a cover slip correction collar (see the photo to the right). These collars have a graduated scale that corresponds to the thickness, in millimeters, of a cover slip being focused through during inspection and laser scanning applications. Both objectives' collars have a scale for fused silica cover slips; in addition, the 1064 nm variant has a scale for silicon carbide cover slips. The scales span the majority of the objectives' circumference, allowing for smooth, precise adjustment. Once a the correct position is found, the collar can be locked in place by tightening the setscrew below it with the included 0.050" hex key. Custom graduations for specific cover glass materials including sapphire (Al2O3), silicon (Si), silicon carbide (SiC), gallium arsenide (GaAs), and gallium nitride (GaN) can be made on request; please contact Tech Support for more details.

These objectives are capable of producing a near-diffraction-limited spot size when used with a monochromatic source within the 450 - 2100 nm range that fills the entrance aperture. However, if used at a wavelength other than the design wavelength, the effective focal length listed on the Specs tab will shift and the AR coating will no longer be optimized; see the Specs tab for AR coating plots. Custom AR Coatings are available by contacting Tech Support to optimize the performance of these objectives at other wavelengths. When working with wavelengths outside of the visible, consider using some of Thorlabs' laser viewing cards to help locate and align your beam.

Our MicroSpot objectives are externally RMS-threaded (0.800"-36), which allows them to be mounted directly to our fiber launch systems, DIY Cerna Microscope Systems, and microscope objective turret. These microscope objectives can be also be mounted in our cage system, lens tubes, or other SM1-compatible optomechanics using an SM1A3 adapter. Our 5X, 10X, and 20X objectives can be mounted to any of our flexure stages using an HCS013 RMS mount. Our 50X objectives can be mounted to our flexture stages using a combination of an HCS031 mount and the SM1A3 adapter. An objective case (OC2RMS lid and OC22 canister) and aluminum cap (RMSCP1) are available for purchase separately.

For wavelengths between 192 nm - 500 nm, Thorlabs offers UV MicroSpot Laser Focusing Objectives in a number of magnifications; this range covers many excimer lasers which cure photoresist, such as KrF lasers (248 nm) and ArF lasers (193 nm).

Item # λc Ma WD EFL PFL NA EA OFN TTyp Diffraction-Limited
Spot Sizeb
Click for
Diagram
Cover Glass
Correction
LMH-5X-532 532 nm 5X 35 mm 40 mm 58.9 mm 0.13 9.9 mm 12 >98% 3.9 µm -
LMH-10X-532 10X 15 mm 20 mm 38.9 mm 0.25 9.9 mm 8 >97% 2.0 µm
LMH-20X-532 20X 6 mm 10 mm 40.0 mm 0.40 8.0 mm 14 >96% 1.3 µm
LMH-50X-532 50X 2.5 mmc 4 mm 45.0 mmc 0.60 5.0 mm 22 >95% 0.9 µm 0 - 1.0 mm of Fused Silica
LMH-5X-1064 1064 nm 5X 35 mm 40 mm 58.9 mm 0.13 9.9 mm 12 >98% 7.8 µm -
LMH-10X-1064 10X 15 mm 20 mm 38.9 mm 0.25 9.9 mm 10 >97% 3.9 µm
LMH-20X-1064 20X 6 mm 10 mm 40.0 mm 0.40 8.0 mm 14 >96% 2.5 µm
LMH-50X-1064 50X 2.3 mmc 4 mm 45.0 mmc 0.65 5.3 mm 22 >95% 1.6 µm 0 - 1.0 mm of Fused Silica
0 - 1.2 mm of SiC
  • Determined with a Tube Lens with a 200 mm Focal Length
  • Measured at Center Wavelength
  • Measured Without Cover Slip

λc = Center Wavelength
M = Magnification
WD = Working Distance

EFL = Effective Focal Length
PFL = Parfocal Length
NA = Numerical Aperture

EA = Entrance Aperture
OFN = Optical Field Number
TTyp = Typical Transmission through Entire Objective at λc

Anti-Reflective (AR) Coating Specifications

AR Coating Suffix Average Reflectance
per Surface
Max Reflectance
per Surface
Reflectance Curve
per Surface
Damage Threshold
-532 <0.2% (495 - 570 nm) <0.7% (488 - 580 nm)
<0.2% (503 - 533 nm)

Click for Graph
15.0 J/cm2 (532 nm, 20 Hz, 10 ns, Ø213 µm)
-1064 <0.2% (980 - 1130 nm) <0.7% (960 - 1160 nm)
<0.2% (1000 - 1100 nm)

Click for Graph
20.0 J/cm2 (1064 nm, 20 Hz, 10 ns, Ø395 µm)
Damage Threshold Specifications
Item # Suffix Damage Threshold
-532 15 J/cm2 (532 nm, 20 Hz, 10 ns, Ø213 µm)
-1064 20 J/cm2 (1064 nm, 20 Hz, 10 ns, Ø395 µm)

Damage Threshold Data for High-Power Focusing Objectives AR Coatings

The specifications to the right are measured data for the antireflective (AR) coatings deposited onto the optical surface of our high power focusing objectives. Damage threshold specifications are constant for a given coating type, regardless of the focal length or magnification.

 

Laser Induced Damage Threshold Tutorial

The following is a general overview of how laser induced damage thresholds are measured and how the values may be utilized in determining the appropriateness of an optic for a given application. When choosing optics, it is important to understand the Laser Induced Damage Threshold (LIDT) of the optics being used. The LIDT for an optic greatly depends on the type of laser you are using. Continuous wave (CW) lasers typically cause damage from thermal effects (absorption either in the coating or in the substrate). Pulsed lasers, on the other hand, often strip electrons from the lattice structure of an optic before causing thermal damage. Note that the guideline presented here assumes room temperature operation and optics in new condition (i.e., within scratch-dig spec, surface free of contamination, etc.). Because dust or other particles on the surface of an optic can cause damage at lower thresholds, we recommend keeping surfaces clean and free of debris. For more information on cleaning optics, please see our Optics Cleaning tutorial.

Testing Method

Thorlabs' LIDT testing is done in compliance with ISO/DIS11254 and ISO 21254 specifications.

First, a low-power/energy beam is directed to the optic under test. The optic is exposed in 10 locations to this laser beam for 30 seconds (CW) or for a number of pulses (pulse repetition frequency specified). After exposure, the optic is examined by a microscope (~100X magnification) for any visible damage. The number of locations that are damaged at a particular power/energy level is recorded. Next, the power/energy is either increased or decreased and the optic is exposed at 10 new locations. This process is repeated until damage is observed. The damage threshold is then assigned to be the highest power/energy that the optic can withstand without causing damage. A histogram such as that below represents the testing of one BB1-E02 mirror.

LIDT metallic mirror
The photograph above is a protected aluminum-coated mirror after LIDT testing. In this particular test, it handled 0.43 J/cm2 (1064 nm, 10 ns pulse, 10 Hz, Ø1.000 mm) before damage.
LIDT BB1-E02
Example Test Data
Fluence # of Tested Locations Locations with Damage Locations Without Damage
1.50 J/cm2 10 0 10
1.75 J/cm2 10 0 10
2.00 J/cm2 10 0 10
2.25 J/cm2 10 1 9
3.00 J/cm2 10 1 9
5.00 J/cm2 10 9 1

According to the test, the damage threshold of the mirror was 2.00 J/cm2 (532 nm, 10 ns pulse, 10 Hz, Ø0.803 mm). Please keep in mind that these tests are performed on clean optics, as dirt and contamination can significantly lower the damage threshold of a component. While the test results are only representative of one coating run, Thorlabs specifies damage threshold values that account for coating variances.

Continuous Wave and Long-Pulse Lasers

When an optic is damaged by a continuous wave (CW) laser, it is usually due to the melting of the surface as a result of absorbing the laser's energy or damage to the optical coating (antireflection) [1]. Pulsed lasers with pulse lengths longer than 1 µs can be treated as CW lasers for LIDT discussions.

When pulse lengths are between 1 ns and 1 µs, laser-induced damage can occur either because of absorption or a dielectric breakdown (therefore, a user must check both CW and pulsed LIDT). Absorption is either due to an intrinsic property of the optic or due to surface irregularities; thus LIDT values are only valid for optics meeting or exceeding the surface quality specifications given by a manufacturer. While many optics can handle high power CW lasers, cemented (e.g., achromatic doublets) or highly absorptive (e.g., ND filters) optics tend to have lower CW damage thresholds. These lower thresholds are due to absorption or scattering in the cement or metal coating.

Linear Power Density Scaling

LIDT in linear power density vs. pulse length and spot size. For long pulses to CW, linear power density becomes a constant with spot size. This graph was obtained from [1].

Intensity Distribution

Pulsed lasers with high pulse repetition frequencies (PRF) may behave similarly to CW beams. Unfortunately, this is highly dependent on factors such as absorption and thermal diffusivity, so there is no reliable method for determining when a high PRF laser will damage an optic due to thermal effects. For beams with a high PRF both the average and peak powers must be compared to the equivalent CW power. Additionally, for highly transparent materials, there is little to no drop in the LIDT with increasing PRF.

In order to use the specified CW damage threshold of an optic, it is necessary to know the following:

  1. Wavelength of your laser
  2. Beam diameter of your beam (1/e2)
  3. Approximate intensity profile of your beam (e.g., Gaussian)
  4. Linear power density of your beam (total power divided by 1/e2 beam diameter)

Thorlabs expresses LIDT for CW lasers as a linear power density measured in W/cm. In this regime, the LIDT given as a linear power density can be applied to any beam diameter; one does not need to compute an adjusted LIDT to adjust for changes in spot size, as demonstrated by the graph to the right. Average linear power density can be calculated using the equation below. 

The calculation above assumes a uniform beam intensity profile. You must now consider hotspots in the beam or other non-uniform intensity profiles and roughly calculate a maximum power density. For reference, a Gaussian beam typically has a maximum power density that is twice that of the uniform beam (see lower right).

Now compare the maximum power density to that which is specified as the LIDT for the optic. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately. A good rule of thumb is that the damage threshold has a linear relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 10 W/cm at 1310 nm scales to 5 W/cm at 655 nm):

CW Wavelength Scaling

While this rule of thumb provides a general trend, it is not a quantitative analysis of LIDT vs wavelength. In CW applications, for instance, damage scales more strongly with absorption in the coating and substrate, which does not necessarily scale well with wavelength. While the above procedure provides a good rule of thumb for LIDT values, please contact Tech Support if your wavelength is different from the specified LIDT wavelength. If your power density is less than the adjusted LIDT of the optic, then the optic should work for your application. 

Please note that we have a buffer built in between the specified damage thresholds online and the tests which we have done, which accommodates variation between batches. Upon request, we can provide individual test information and a testing certificate. The damage analysis will be carried out on a similar optic (customer's optic will not be damaged). Testing may result in additional costs or lead times. Contact Tech Support for more information.

Pulsed Lasers

As previously stated, pulsed lasers typically induce a different type of damage to the optic than CW lasers. Pulsed lasers often do not heat the optic enough to damage it; instead, pulsed lasers produce strong electric fields capable of inducing dielectric breakdown in the material. Unfortunately, it can be very difficult to compare the LIDT specification of an optic to your laser. There are multiple regimes in which a pulsed laser can damage an optic and this is based on the laser's pulse length. The highlighted columns in the table below outline the relevant pulse lengths for our specified LIDT values.

Pulses shorter than 10-9 s cannot be compared to our specified LIDT values with much reliability. In this ultra-short-pulse regime various mechanics, such as multiphoton-avalanche ionization, take over as the predominate damage mechanism [2]. In contrast, pulses between 10-7 s and 10-4 s may cause damage to an optic either because of dielectric breakdown or thermal effects. This means that both CW and pulsed damage thresholds must be compared to the laser beam to determine whether the optic is suitable for your application.

Pulse Duration t < 10-9 s 10-9 < t < 10-7 s 10-7 < t < 10-4 s t > 10-4 s
Damage Mechanism Avalanche Ionization Dielectric Breakdown Dielectric Breakdown or Thermal Thermal
Relevant Damage Specification No Comparison (See Above) Pulsed Pulsed and CW CW

When comparing an LIDT specified for a pulsed laser to your laser, it is essential to know the following:

Energy Density Scaling

LIDT in energy density vs. pulse length and spot size. For short pulses, energy density becomes a constant with spot size. This graph was obtained from [1].

  1. Wavelength of your laser
  2. Energy density of your beam (total energy divided by 1/e2 area)
  3. Pulse length of your laser
  4. Pulse repetition frequency (prf) of your laser
  5. Beam diameter of your laser (1/e2 )
  6. Approximate intensity profile of your beam (e.g., Gaussian)

The energy density of your beam should be calculated in terms of J/cm2. The graph to the right shows why expressing the LIDT as an energy density provides the best metric for short pulse sources. In this regime, the LIDT given as an energy density can be applied to any beam diameter; one does not need to compute an adjusted LIDT to adjust for changes in spot size. This calculation assumes a uniform beam intensity profile. You must now adjust this energy density to account for hotspots or other nonuniform intensity profiles and roughly calculate a maximum energy density. For reference a Gaussian beam typically has a maximum energy density that is twice that of the 1/e2 beam.

Now compare the maximum energy density to that which is specified as the LIDT for the optic. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately [3]. A good rule of thumb is that the damage threshold has an inverse square root relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 1 J/cm2 at 1064 nm scales to 0.7 J/cm2 at 532 nm):

Pulse Wavelength Scaling

You now have a wavelength-adjusted energy density, which you will use in the following step.

Beam diameter is also important to know when comparing damage thresholds. While the LIDT, when expressed in units of J/cm², scales independently of spot size; large beam sizes are more likely to illuminate a larger number of defects which can lead to greater variances in the LIDT [4]. For data presented here, a <1 mm beam size was used to measure the LIDT. For beams sizes greater than 5 mm, the LIDT (J/cm2) will not scale independently of beam diameter due to the larger size beam exposing more defects.

The pulse length must now be compensated for. The longer the pulse duration, the more energy the optic can handle. For pulse widths between 1 - 100 ns, an approximation is as follows:

Pulse Length Scaling

Use this formula to calculate the Adjusted LIDT for an optic based on your pulse length. If your maximum energy density is less than this adjusted LIDT maximum energy density, then the optic should be suitable for your application. Keep in mind that this calculation is only used for pulses between 10-9 s and 10-7 s. For pulses between 10-7 s and 10-4 s, the CW LIDT must also be checked before deeming the optic appropriate for your application.

Please note that we have a buffer built in between the specified damage thresholds online and the tests which we have done, which accommodates variation between batches. Upon request, we can provide individual test information and a testing certificate. Contact Tech Support for more information.


[1] R. M. Wood, Optics and Laser Tech. 29, 517 (1998).
[2] Roger M. Wood, Laser-Induced Damage of Optical Materials (Institute of Physics Publishing, Philadelphia, PA, 2003).
[3] C. W. Carr et al., Phys. Rev. Lett. 91, 127402 (2003).
[4] N. Bloembergen, Appl. Opt. 12, 661 (1973).

In order to illustrate the process of determining whether a given laser system will damage an optic, a number of example calculations of laser induced damage threshold are given below. For assistance with performing similar calculations, we provide a spreadsheet calculator that can be downloaded by clicking the button to the right. To use the calculator, enter the specified LIDT value of the optic under consideration and the relevant parameters of your laser system in the green boxes. The spreadsheet will then calculate a linear power density for CW and pulsed systems, as well as an energy density value for pulsed systems. These values are used to calculate adjusted, scaled LIDT values for the optics based on accepted scaling laws. This calculator assumes a Gaussian beam profile, so a correction factor must be introduced for other beam shapes (uniform, etc.). The LIDT scaling laws are determined from empirical relationships; their accuracy is not guaranteed. Remember that absorption by optics or coatings can significantly reduce LIDT in some spectral regions. These LIDT values are not valid for ultrashort pulses less than one nanosecond in duration.

Intensity Distribution
A Gaussian beam profile has about twice the maximum intensity of a uniform beam profile.

CW Laser Example
Suppose that a CW laser system at 1319 nm produces a 0.5 W Gaussian beam that has a 1/e2 diameter of 10 mm. A naive calculation of the average linear power density of this beam would yield a value of 0.5 W/cm, given by the total power divided by the beam diameter:

CW Wavelength Scaling

However, the maximum power density of a Gaussian beam is about twice the maximum power density of a uniform beam, as shown in the graph to the right. Therefore, a more accurate determination of the maximum linear power density of the system is 1 W/cm.

An AC127-030-C achromatic doublet lens has a specified CW LIDT of 350 W/cm, as tested at 1550 nm. CW damage threshold values typically scale directly with the wavelength of the laser source, so this yields an adjusted LIDT value:

CW Wavelength Scaling

The adjusted LIDT value of 350 W/cm x (1319 nm / 1550 nm) = 298 W/cm is significantly higher than the calculated maximum linear power density of the laser system, so it would be safe to use this doublet lens for this application.

Pulsed Nanosecond Laser Example: Scaling for Different Pulse Durations
Suppose that a pulsed Nd:YAG laser system is frequency tripled to produce a 10 Hz output, consisting of 2 ns output pulses at 355 nm, each with 1 J of energy, in a Gaussian beam with a 1.9 cm beam diameter (1/e2). The average energy density of each pulse is found by dividing the pulse energy by the beam area:

Pulse Energy Density

As described above, the maximum energy density of a Gaussian beam is about twice the average energy density. So, the maximum energy density of this beam is ~0.7 J/cm2.

The energy density of the beam can be compared to the LIDT values of 1 J/cm2 and 3.5 J/cm2 for a BB1-E01 broadband dielectric mirror and an NB1-K08 Nd:YAG laser line mirror, respectively. Both of these LIDT values, while measured at 355 nm, were determined with a 10 ns pulsed laser at 10 Hz. Therefore, an adjustment must be applied for the shorter pulse duration of the system under consideration. As described on the previous tab, LIDT values in the nanosecond pulse regime scale with the square root of the laser pulse duration:

Pulse Length Scaling

This adjustment factor results in LIDT values of 0.45 J/cm2 for the BB1-E01 broadband mirror and 1.6 J/cm2 for the Nd:YAG laser line mirror, which are to be compared with the 0.7 J/cm2 maximum energy density of the beam. While the broadband mirror would likely be damaged by the laser, the more specialized laser line mirror is appropriate for use with this system.

Pulsed Nanosecond Laser Example: Scaling for Different Wavelengths
Suppose that a pulsed laser system emits 10 ns pulses at 2.5 Hz, each with 100 mJ of energy at 1064 nm in a 16 mm diameter beam (1/e2) that must be attenuated with a neutral density filter. For a Gaussian output, these specifications result in a maximum energy density of 0.1 J/cm2. The damage threshold of an NDUV10A Ø25 mm, OD 1.0, reflective neutral density filter is 0.05 J/cm2 for 10 ns pulses at 355 nm, while the damage threshold of the similar NE10A absorptive filter is 10 J/cm2 for 10 ns pulses at 532 nm. As described on the previous tab, the LIDT value of an optic scales with the square root of the wavelength in the nanosecond pulse regime:

Pulse Wavelength Scaling

This scaling gives adjusted LIDT values of 0.08 J/cm2 for the reflective filter and 14 J/cm2 for the absorptive filter. In this case, the absorptive filter is the best choice in order to avoid optical damage.

Pulsed Microsecond Laser Example
Consider a laser system that produces 1 µs pulses, each containing 150 µJ of energy at a repetition rate of 50 kHz, resulting in a relatively high duty cycle of 5%. This system falls somewhere between the regimes of CW and pulsed laser induced damage, and could potentially damage an optic by mechanisms associated with either regime. As a result, both CW and pulsed LIDT values must be compared to the properties of the laser system to ensure safe operation.

If this relatively long-pulse laser emits a Gaussian 12.7 mm diameter beam (1/e2) at 980 nm, then the resulting output has a linear power density of 5.9 W/cm and an energy density of 1.2 x 10-4 J/cm2 per pulse. This can be compared to the LIDT values for a WPQ10E-980 polymer zero-order quarter-wave plate, which are 5 W/cm for CW radiation at 810 nm and 5 J/cm2 for a 10 ns pulse at 810 nm. As before, the CW LIDT of the optic scales linearly with the laser wavelength, resulting in an adjusted CW value of 6 W/cm at 980 nm. On the other hand, the pulsed LIDT scales with the square root of the laser wavelength and the square root of the pulse duration, resulting in an adjusted value of 55 J/cm2 for a 1 µs pulse at 980 nm. The pulsed LIDT of the optic is significantly greater than the energy density of the laser pulse, so individual pulses will not damage the wave plate. However, the large average linear power density of the laser system may cause thermal damage to the optic, much like a high-power CW beam.

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. 

Laser Safety Signs
Laser Glasses Alignment Tools Shutter and Controllers
Laser Viewing Cards Blackout Materials Enclosure Systems

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 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.  Class 1
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.  Class 1M
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).  Class 2
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.  Class 2M
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.  Class 3R
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.  Class 3B
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.  Class 4
All class 2 lasers (and higher) must display, in addition to the corresponding sign above, this triangular warning sign  Warning Symbol

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Posted Comments:
Poster:p.kleingarn
Posted Date:2017-11-28 11:53:28.36
I've got a question regarding the LMH-10x-532nm Objective. I'm working with the optical Breakdown in borosilikat-glas and i'm wondering how the spherical Abberations would influence my results. Can you give me any information about the wavefront abberation coefficient/transmitted wavefront error maybe? This would be very appreciated, thanks ! besten regards Philipp
Poster:linlinchiayu
Posted Date:2017-07-04 22:05:00.537
Can I receive the wavelength range information of LMH-20X-1064 and LMH-10X-1064?
Poster:nbayconich
Posted Date:2017-07-11 10:58:47.0
Thank you for contacting Thorlabs. I will reach out to you directly with more information on the transmission of LMH-20X-1064 and LMH-10X-1064.
Poster:marin.vojkovic
Posted Date:2017-06-27 10:46:21.98
Can you please tell me what coating is used for the objective and if it is suitable for working in the vacuum? If not, what would the price be for an objective suitable for vacuum? By coating, I mean the whole objective, not just the lens. Thank you in advance!
Poster:tfrisch
Posted Date:2017-08-03 11:31:47.0
Hello, thank you for contacting Thorlabs. We can offer a custom vacuum compatible version. I will reach out to you directly.
Poster:jelke.wibbeke
Posted Date:2016-10-10 09:57:25.37
We are using the LMH-5X-1064 on a femtosecond laser. It occours that we can find two more focus spots (with less intensity) symmetrically about 2mm to the left and the right of the actual focus spot. Any clue?
Poster:jlow
Posted Date:2016-10-10 11:13:42.0
Response from Jeremy at Thorlabs: We will contact you directly about troubleshooting this.
Poster:erica.block
Posted Date:2016-07-29 13:30:02.18
Could you make one of these high power MicroSpot focusing objectives with a 850nm AR coating?
Poster:o.soroka
Posted Date:2015-11-18 13:41:26.86
Can this objective be used in the UHV?
Poster:besembeson
Posted Date:2015-11-20 09:34:48.0
Response from Bweh at Thorlabs USA: The stock item like the LMH-5X-532 is not vacuum compatible as there are certain air-pockets and anodized components inside that will out-gas. We can provide a special vacuum compatible version that may be suitable for your application. I will contact you.
Poster:andrefilipedrosa
Posted Date:2015-07-14 19:58:24.633
Hello, is this objective lens able to be scanned? ty
Poster:besembeson
Posted Date:2015-09-23 12:03:35.0
Response from Bweh at Thorlabs USA: The design is not telecentric and the clear aperture may not be large enough so this will not be suitable for scanning applications. You can find several scanning objectives at the following link: http://www.thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=2910
Poster:suwas.nikumb
Posted Date:2014-02-10 09:37:53.92
Do you have microscope objectives at 532nm and 800nm with atleast 12-15mm entrance aperture?
Poster:besembeson
Posted Date:2014-02-12 01:59:58.0
Response from Bweh E. at Thorlabs: Thanks for contacting Thorlabs. At this time, we do not carry such objectives that meet your requirements. We however have several other objectives at the following page: http://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1044.
Poster:lvtaohn
Posted Date:2013-09-17 19:08:25.967
Do you have 40times or 60 times high power focusing objective 1064nm or 532nm? I need them in these days. Please let me know if you have them. Thank you!
Poster:jlow
Posted Date:2013-09-19 14:09:00.0
Response from Jeremy at Thorlabs: We do not currently have these short focal length objectives for high power application. I have logged this in our internal forum and we will look into whether we could make this.
Poster:rpscott
Posted Date:2013-05-29 17:06:42.537
Is the transmission for the 1064nm version of the objectives similar at 1037nm?
Poster:tcohen
Posted Date:2013-05-30 02:28:00.0
Response from Tim at Thorlabs: Yes. The number of surfaces in each objective is different and therefore deviation away from the design wavelength will have more of an impact on transmission for the 20X vs the 10X, for example. However, at your desired wavelength the total transmission for each is similar.
Poster:tcohen
Posted Date:2012-08-23 16:25:00.0
Response from Tim at Thorlabs: Thank you for contacting us. I’ve emailed you to go over this objective and supply some representative data.
Poster:song31037
Posted Date:2012-08-23 15:19:04.0
Can I receive the wavelength range information of LMH-20X-1064?
Poster:tcohen
Posted Date:2012-02-29 15:56:00.0
Response from Tim at Thorlabs: Thank you for your feedback on the LMH-10X-532. I am looking into the materials we use for this objective and will post an update soon.
Poster:g.laliberte
Posted Date:2012-02-29 10:13:58.0
I'm intersted in a microscope objective that would be made of non magnetic material. Do you have any data about the housing material of that lens? THanks
Poster:jjurado
Posted Date:2011-07-08 08:58:00.0
Response from Javier at Thorlabs to last poster: Thank you very much for contacting us. For this objective, the absorption in the glass itself is almost negligible, and if we assume 3.5% loss at each surface we would end up with a total transmission in the neighborhood of 80%. However, keep in mind that the chromatic shift of roughly 0.2 mm will slightly affect the performance of this objective. Also, we do not currently have an objective specifically designed for operation at 980 and 1550 nm. Please contact us at techsupport@thorlabs.com if you would like to discuss your application a bit further.
Poster:
Posted Date:2011-07-07 14:17:40.0
I am working with this objective (LMH-10X-1064), but I have beam at 1550nm. So I want to know the transmission spectrum of this objective especialy for 1550nm). Is there any particular objective design to work at 980nm and 1550nm?
Poster:apalmentieri
Posted Date:2009-12-31 17:12:33.0
A response from Adam at Thorlabs to Ilday: There was a server glitch and we are working to bring this page online. Please note that we do have stock on most of these objectives and they can be ordered direct through our sales department, sales@thorlabs.com or 973-300-3000, while these parts are not on the website. I will email you with more information.
Poster:ilday
Posted Date:2009-12-31 17:01:39.0
I wanted to purchase this product, which was available until yesterday, however it has disappeared from the webpage. Is that a server glitch or did you discontinue the product?

Thorlabs offers a wide selection of optics optimized for use with Nd:YAG lasers. Please see below for more information.

Nd:YAG Optics Selection
Dielectric Mirrors Ultrafast Mirrors
Laser Line Mirrors, 1064 nm, 532 nm, 355 nm, 266 nm Right-Angle Prism Mirrors, Nd:YAG Laser Lines Cage Cube-Mounted Turning Prism Mirrors Nd:Yag Ultrafast Mirrors
Laser Line Mirrors,
1064 nm, 532 nm, 355 nm, 266 nm
Right-Angle Prism Mirrors,
1064 nm, 532 nm
Cage Cube-Mounted Prism Mirrors,
1064 nm, 532 nm
Low GDD Ultrafast Mirrors,
1064 nm or 532 nm
Beamsplitters Objectives
Harmonic Beamsplitters, 1064 nm, 532 nm, 355 nm, 266 nm High-Power Polarizing Beamsplitter Cubes, 1064 nm, 532 nm High Power Focusing Objectives, 1064 nm, 532 nm
Harmonic Beamsplitters,
1064 nm, 532 nm, 355 nm, 266 nm
High-Power Polarizing Beamsplitter Cubes, 1064 nm, 532 nm: Unmounted or Mounted Non-Polarizing Plate Beamsplitters, 1064 nm, 532 nm High Power Focusing Objectives,
1064 nm, 532 nm
Lenses Filters
UVFS Plano-Convex Lenses, 1064 nm, 532 nm Air-Spaced Doublets, 1064 nm, 532 nm Laser Line Filters, 1064 nm Laser Line Filters, 532 nm
UVFS Plano-Convex Lenses,
1064 nm, 532 nm:
Unmounted or Mounted
Air-Spaced Doublets,
1064 nm, 532 nm
Laser Line Filters, 1064 nm:
Standard or Premium
Laser Line Filters, 532 nm:
Standard or Premium

532 nm, High-Power MicroSpot Focusing Objectives

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
LMH-5X-532 Support Documentation
LMH-5X-532532 nm, 5X High-Power MicroSpot Focusing Objective, 0.13 NA, 35 mm WD
$839.00
Today
LMH-10X-532 Support Documentation
LMH-10X-532532 nm, 10X High-Power MicroSpot Focusing Objective, 0.25 NA, 15 mm WD
$1,033.00
Today
LMH-20X-532 Support Documentation
LMH-20X-532532 nm, 20X High-Power MicroSpot Focusing Objective, 0.40 NA, 6 mm WD
$1,534.00
3-5 Days
LMH-50X-532 Support Documentation
LMH-50X-532532 nm, 50X High-Power MicroSpot Focusing Objective with Correction Collar, 0.60 NA, 2.5 mm WD
$3,500.00
Today

1064 nm, High-Power MicroSpot Focusing Objectives

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
LMH-5X-1064 Support Documentation
LMH-5X-10641064 nm, 5X High-Power MicroSpot Focusing Objective, 0.13 NA, 35 mm WD
$839.00
Today
LMH-10X-1064 Support Documentation
LMH-10X-10641064 nm, 10X High-Power MicroSpot Focusing Objective, 0.25 NA, 15 mm WD
$1,033.00
Today
LMH-20X-1064 Support Documentation
LMH-20X-10641064 nm, 20X High-Power MicroSpot Focusing Objective, 0.40 NA, 6 mm WD
$1,534.00
3-5 Days
LMH-50X-1064 Support Documentation
LMH-50X-1064NEW!Customer Inspired!1064 nm, 50X High-Power MicroSpot Focusing Objective with Correction Collar, 0.65 NA, 2.3 mm WD
$3,500.00
Today
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