Abstract: An object of the present invention is to ensure that, during adjustment of a spring load by an adjuster, total fully-stretched lengths of an outer tube and an inner tube remain unchanged and the adjuster is prevented from protruding from an upper surface of a cap. In a hydraulic shock absorber 10, a spring load adjusting device 30 is configured such that an adjuster 31 is provided at an upper end portion of a vehicle body side tube 11, a push rod 33 that is moved up and down by the adjuster 31 is penetrated into a hollow portion of a hollow rod 23, a suspension spring 35 is pressurized by the push rod 33 that protrudes from the hollow portion of the hollow rod 23 to the inside of a wheel side tube 12, and the spring load of the suspension spring 35 can be adjusted by the up-and-down motion of the push rod 33 caused by the adjuster 31.

Abstract: An object of the present invention is to ensure that, during adjustment of a spring load by an adjuster, total fully-stretched lengths of an outer tube and an inner tube remain unchanged and the adjuster is prevented from protruding from an upper surface of a cap. In a hydraulic shock absorber 10, a spring load adjusting device 30 is configured such that an adjuster 31 is provided at an upper end portion of a vehicle body side tube 11, a push rod 33 that is moved up and down by the adjuster 31 is penetrated into a hollow portion of a hollow rod 23, a suspension spring 35 is pressurized by the push rod 33 that protrudes from the hollow portion of the hollow rod 23 to the inside of a wheel side tube 12, and the spring load of the suspension spring 35 can be adjusted by the up-and-down motion of the push rod 33 caused by the adjuster 31.

Abstract: The invention is designed to calibrate a low-level optical power by a substitution method using a pulse generating section in which a light-shielding disk having a sectorial opening, as a component capable of accurate optical attenuation, is rotated in a light beam to generate an intermittent pulse signal having a duty ratio corresponding to the size of the opening, and the pulse signal is averaged to obtain an optical attenuation equal to the duty ratio. More specifically, while an object to be calibrated is set in a given standard state, a first pulse train having a duty ratio d1=Tw.sub.1 /Tf.sub.1 is input to the object, and an average optical power value A of an output from the object is measured and stored. Subsequently, a second pulse train having a duty ratio d2=Tw.sub.2 /Tf.sub.2 is input to the object, and the object is adjusted such that an average optical power value of an output from the object becomes the value A.