L40(500)A-LP2-DIF-35

The new “LP2” type sensors are specially designed for beams having high power and high power density (and for pulsed beams, high energy density). The LP2 sensors are replacing the equivalent LP1 sensors; as impressive as the LP1 is, the LP2 was developed with the following improvements:

• Very high damage threshold, for both power density and energy density, for long pulse and CW beams;
• Spectrally flat; since its absorption remains constant at widely differing wavelengths, this means that sensors based on the LP2 can be used for "white light" or polychromatic beams;
• Very high level of absorption (as high as 96%, depending on wavelength), meaning much less light is scattered back, which for high power beams is an important benefit;
• The absorption is also largely independent of incident angle, which means it can be used for divergent beams too.

The sensors with a continual response curve such as the ones listed above come with preset "favorite" wavelengths. If these "favorite" wavelengths do not match the application wavelength you are using they can be changed by performing the instructions below, which are for the Vega meter. For your specific meter, please see the User Manual.

• While the Vega is off, plug in the head. Switch on the Vega.
• From the main measurement screen, press "Laser" to select the correct laser wavelength. If you want to save this new wavelength as the startup default, press "Save" before exiting. If the wavelength you want is not among the wavelengths in the six wavelengths listed and you want to change or add a wavelength, see the next step
• Changing Chosen Wavelengths:
  
  • From the power measurement screen select "Laser" and enter. Move to the wavelength you wish to change or add. Press the right navigation key.
  • Using the up/down keys to change each number and the right/left keys to move to the next number, key in the desired wavelength. Press the Enter key to exit. If you wish to save this new wavelength as one of the 6 favorite wavelengths, press "Save".

Note: Saving the new wavelength in the Modify screen will not set this wavelength as the default startup wavelength. To do so, you must follow the instructions in Step 2 above.

Well, partly right.

Ophir has for many years had a few sensors that are designed for intermittent use. They are marked by two numbers like 50(150), which means it can measure 50 W continuously, or 150 W for a brief exposure (1.5 minutes in this example). Keeping in mind that power is energy over time, and that it is the total energy absorbed over time that causes a sensor to heat up, it should be possible to expose a sensor to “too high” power but only for a short time, and have the sensor survive the experience. The sensor can treat that short exposure as if it were just one long “single shot” pulse, and measure the energy of that pulse. Divide the energy by the (known) pulse width, and that gives the power during the pulse. (It can’t measure power directly this way, though, since a thermal sensor’s response time to power is itself a few seconds). For example, the moderate-power L40(250)A-LP2-50 has a 10KJ energy scale (several other sensors also have multi kJ scales); to measure power of an 8KW beam, we can fire the laser for 0.5 seconds with the sensor in energy mode, and we’ll measure 4KJ energy in the “pulse”. Dividing that by 0.5 seconds gives the 8KW beam power. Of course we then need to wait for the sensor to cool before repeating, but in some applications that may be perfectly OK
If you have a Juno, Juno+, Centauri or StarBright meter, you can do the above automatically, with any power sensor, using StarBright’s “Pulsed Power” function where you input the pulse duration and the meter will give the readout directly in power.

校正精度に影響する場合もありますので、パワーセンサ/エネルギセンサの詳しいクリーニング方法について、ご不明の方はお問合せください。

Absorber Type	Umicore #2 Substrate Cleaner	Acetone	Methanol	Umicore #2 + Acetone
Alumina
Thermal BB
Pyro BB
BF
Comet BB
EX
HD
HE
HE1
HL
LP
LP1
Pyro Metallic
P type
N type
UV
10K-W(Reflector)

オフィール社のセンサとディスプレイ/インターフェースは個別に校正されています。各ディスプレイ/インターフェースのアナログ出力精度は同じで、約0.2％程度でしかないのです。センサはディスプレイ/インターフェースとは別に、固体ごとにNIST準拠の基準器で校正され、校正情報はセンサ直属ケーブル先端にあるSHコネクタ内部のROMに記録されています。センサをディスプレイ/インターフェースに接続すると、ディスプレイ/インターフェースはセンサからの校正係数を読み込みます。オフィール社のセンサ単体での代表的な校正精度は+/-3%で、ディスプレイ/インターフェース単体での校正精度は約0.2％ですから、合成された校正精度は√(3のニ乗+0.2の二乗)となります。その変化分はほぼ考慮しなくてよい誤差範囲なので、センサはいずれのディスプレイ/インターフェースと接続することができます。

オフィールにおける校正精度は通常、標準偏差で2σでのものです。つまり、精度が +/-3%と記載されている場合、センサの95.4% のものはこの範囲に入り、99.7% のものは+/-4% の範囲に入ることを示します。校正精度については、別途お問合せください。参考： https://www.ophiropt.com/laser-measurement-instruments/laser-power-energy-meters/tutorial/calibration-procedure

センサのモデルによりますが、30(150)AやL40(150)Aは、断続的に150W程度測定することができます。

ダメージスレッショルドに対してギリギリ仕様範囲内のセンサは推奨いたしません。ダメージスレッショルドは単純な数値ではなく、様々な要素に依存するからです。ウェブサイトのセンサファインダで検索する場合には、50％以下でのダメージスレッショルドでご検討ください。モデル選定にお困りの場合は、弊社 レーザ計測機器部 info@ophirjapan.co.jpまでお問合せください。

サーマルセンサのダメージスレッショルドは、パワー密度だけでなく、出力レベルに依存します。センサディスク自体が、ハイパワーが入射されると、より熱を吸収するからです。例えば、オフィール社のBB型コーティングを採用したセンサの場合、10W入射の場合は50kW/cm²ですが、300W入射の場合は10kW/cm²となります。オフィール社のダメージスレッショルドは、特定のセンサに対して最大パワーを入射した場合の値とされています。他の製造メーカのほとんどは、ここまでは行われていません。仕様を比較する場合、カタログ数値だけの比較ではなく、このような背景も考慮してください。

特に指定がない限り、オフィールのセンサー及びディスプレイは購入日から18か月以内に初回の校正を受けて頂く事をお勧め致します。その後は年次定期校正を受けて頂く事を推奨致します。

In theory, if a beam is completely parallel and fits within the aperture of a sensor, then it should make no difference at all what the distance is; it will be the same number of photons (ignoring absorption by the air, which is negligible except in the UV below 250nm). If, nevertheless, you do see such a distance dependence, there could be one of the following effects happening:

• If you are using a thermal type power sensor, you might actually be measuring heat from the laser itself; when very close to the laser, the thermal sensor might be “feeling” the laser’s own heat. That would not, however, continue to have an effect at more than a few cm distance unless the light source is weak and the heat source is strong.
• Beam geometry – The beam may not be parallel and may be diverging. Often, the lower intensity wings of the beam have greater divergence rate than the main portion of the beam. These may be missing the sensor's aperture as the distance increases. To check that you'd need to use a profiler, or perhaps a BeamTrack PPS (Power/Position/Size) sensor.
• If you are measuring pulse energies with a diffuser-based pyroelectric sensor: Some users find that when they start with the sensor right up close to the laser and move it away, the readings drop sharply (typically by some 6%) over the first few cm. This is likely caused by multiple reflections between the diffuser and the laser device, which at the closest distance might be causing an incorrectly high reading. You should back off from the source by at least some 5cm, more if the beam is not too divergent.

Needless to say, it’s also important to be sure to have a steady setup; a sensor held by hand could easily be moved around involuntarily, which could cause partial or complete missing of the sensor’s aperture at increasing distance, particularly for an invisible beam.

水冷センサの場合は規定された冷却水量、水冷温度範囲、水温変化を守らないと、表示値が影響されますので安定した冷却状態が不可欠です。一方で強制ファン空冷タイプのセンサは、センサの最大パワー（レーザ連続照射時）に対して、環境温度25℃で設計されています。この場合の最大パワーにおいて、75℃を超えない筐体温度でご使用ください。室内温度の上昇に従って、最大入射パワーは下げてください。例えば室内温度が35℃の場合、(75-32)/(75-25)=最大パワーの80%が最大許容測定パワーになります。（※急激な室内温度変化を除きます。）